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Sönmez MI, Goldack S, Nurkkala E, Schulz C, Klampe B, Schulze T, Hansen A, Eschenhagen T, Koivumäki J, Christ T. Human induced pluripotent stem cell-derived atrial cardiomyocytes recapitulate contribution of the slowly activating delayed rectifier currents IKs to repolarization in the human atrium. Europace 2024; 26:euae140. [PMID: 38788213 PMCID: PMC11167676 DOI: 10.1093/europace/euae140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 05/23/2024] [Indexed: 05/26/2024] Open
Abstract
AIMS Human induced pluripotent stem cell-derived atrial cardiomyocytes (hiPSC-aCM) could be a helpful tool to study the physiology and diseases of the human atrium. To fulfil this expectation, the electrophysiology of hiPSC-aCM should closely resemble the situation in the human atrium. Data on the contribution of the slowly activating delayed rectifier currents (IKs) to repolarization are lacking for both human atrium and hiPSC-aCM. METHODS AND RESULTS Human atrial tissues were obtained from patients with sinus rhythm (SR) or atrial fibrillation (AF). Currents were measured in human atrial cardiomyocytes (aCM) and compared with hiPSC-aCM and used to model IKs contribution to action potential (AP) shape. Action potential was recorded by sharp microelectrodes. HMR-1556 (1 µM) was used to identify IKs and to estimate IKs contribution to repolarization. Less than 50% of hiPSC-aCM and aCM possessed IKs. Frequency of occurrence, current densities, activation/deactivation kinetics, and voltage dependency of IKs did not differ significantly between hiPSC-aCM and aCM, neither in SR nor AF. β-Adrenoceptor stimulation with isoprenaline did not increase IKs neither in aCM nor in hiPSC-aCM. In tissue from SR, block of IKs with HMR-1556 did not lengthen the action potential duration, even when repolarization reserve was reduced by block of the ultra-rapid repolarizing current with 4-aminopyridine or the rapidly activating delayed rectifier potassium outward current with E-4031. CONCLUSION I Ks exists in hiPSC-aCM with biophysics not different from aCM. As in adult human atrium (SR and AF), IKs does not appear to relevantly contribute to repolarization in hiPSC-aCM.
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Affiliation(s)
- Muhammed Ikbal Sönmez
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Martinistrasse 52, 20246 Hamburg, Germany
| | - Silvana Goldack
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Martinistrasse 52, 20246 Hamburg, Germany
- Department of Pharmacology and Toxicology, Medical Faculty Carl Gustav Carus, Dresden University of Technology, Dresden, Germany
| | - Elina Nurkkala
- Tech Unit and Centre of Excellence in Body-on-Chip Research (CoEBoC), Faculty of Medicine and Health Technology, Tampere University, Tampere, Finnland
| | - Carl Schulz
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Martinistrasse 52, 20246 Hamburg, Germany
| | - Birgit Klampe
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Martinistrasse 52, 20246 Hamburg, Germany
| | - Thomas Schulze
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Martinistrasse 52, 20246 Hamburg, Germany
| | - Arne Hansen
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Martinistrasse 52, 20246 Hamburg, Germany
| | - Thomas Eschenhagen
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Martinistrasse 52, 20246 Hamburg, Germany
| | - Jussi Koivumäki
- Tech Unit and Centre of Excellence in Body-on-Chip Research (CoEBoC), Faculty of Medicine and Health Technology, Tampere University, Tampere, Finnland
| | - Torsten Christ
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Hamburg/Kiel/Lübeck, Martinistrasse 52, 20246 Hamburg, Germany
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Chapotte-Baldacci CA, Pierre M, Djemai M, Pouliot V, Chahine M. Biophysical properties of Na V1.5 channels from atrial-like and ventricular-like cardiomyocytes derived from human induced pluripotent stem cells. Sci Rep 2023; 13:20685. [PMID: 38001331 PMCID: PMC10673932 DOI: 10.1038/s41598-023-47310-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 11/12/2023] [Indexed: 11/26/2023] Open
Abstract
Generating atrial-like cardiomyocytes derived from human induced pluripotent stem cells (hiPSCs) is crucial for modeling and treating atrial-related diseases, such as atrial arrythmias including atrial fibrillations. However, it is essential to obtain a comprehensive understanding of the electrophysiological properties of these cells. The objective of the present study was to investigate the molecular, electrical, and biophysical properties of several ion channels, especially NaV1.5 channels, in atrial hiPSC cardiomyocytes. Atrial cardiomyocytes were obtained by the differentiation of hiPSCs treated with retinoic acid (RA). The quality of the atrial specification was assessed by qPCR, immunocytofluorescence, and western blotting. The electrophysiological properties of action potentials (APs), Ca2+ dynamics, K+ and Na+ currents were investigated using patch-clamp and optical mapping approaches. We evaluated mRNA transcript and protein expressions to show that atrial cardiomyocytes expressed higher atrial- and sinoatrial-specific markers (MYL7, CACNA1D) and lower ventricular-specific markers (MYL2, CACNA1C, GJA1) than ventricular cardiomyocytes. The amplitude, duration, and steady-state phase of APs in atrial cardiomyocytes decreased, and had a shape similar to that of mature atrial cardiomyocytes. Interestingly, NaV1.5 channels in atrial cardiomyocytes exhibited lower mRNA transcripts and protein expression, which could explain the lower current densities recorded by patch-clamp. Moreover, Na+ currents exhibited differences in activation and inactivation parameters. These differences could be explained by an increase in SCN2B regulatory subunit expression and a decrease in SCN1B and SCN4B regulatory subunit expressions. Our results show that a RA treatment made it possible to obtain atrial cardiomyocytes and investigate differences in NaV1.5 channel properties between ventricular- and atrial-like cells.
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Affiliation(s)
- Charles-Albert Chapotte-Baldacci
- Department of Medicine, Laval University, Quebec City, QC, Canada
- CERVO Brain Research Centre, 2601, chemin de la Canardière, Quebec City, QC, G1J 2G3, Canada
| | - Marion Pierre
- Department of Medicine, Laval University, Quebec City, QC, Canada
- CERVO Brain Research Centre, 2601, chemin de la Canardière, Quebec City, QC, G1J 2G3, Canada
| | - Mohammed Djemai
- Department of Medicine, Laval University, Quebec City, QC, Canada
- CERVO Brain Research Centre, 2601, chemin de la Canardière, Quebec City, QC, G1J 2G3, Canada
| | - Valérie Pouliot
- CERVO Brain Research Centre, 2601, chemin de la Canardière, Quebec City, QC, G1J 2G3, Canada
| | - Mohamed Chahine
- CERVO Brain Research Centre, 2601, chemin de la Canardière, Quebec City, QC, G1J 2G3, Canada.
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Schulz C, Sönmez M, Krause J, Schwedhelm E, Bangfen P, Alihodzic D, Hansen A, Eschenhagen T, Christ T. A critical role of retinoic acid concentration for the induction of a fully human-like atrial action potential phenotype in hiPSC-CM. Stem Cell Reports 2023; 18:2096-2107. [PMID: 37922915 PMCID: PMC10679650 DOI: 10.1016/j.stemcr.2023.10.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 10/05/2023] [Accepted: 10/09/2023] [Indexed: 11/07/2023] Open
Abstract
Retinoic acid (RA) induces an atrial phenotype in human induced pluripotent stem cells (hiPSCs), but expression of atrium-selective currents such as the ultrarapid (IKur) and acetylcholine-stimulated K+ current is variable and less than in the adult human atrium. We suspected methodological issues and systematically investigated the concentration dependency of RA. RA treatment increased IKur concentration dependently from 1.1 ± 0.54 pA/pF (0 RA) to 3.8 ± 1.1, 5.8 ± 2.5, and 12.2 ± 4.3 at 0.01, 0.1, and 1 μM, respectively. Only 1 μM RA induced enough IKur to fully reproduce human atrial action potential (AP) shape and a robust shortening of APs upon carbachol. We found that sterile filtration caused substantial loss of RA. We conclude that 1 μM RA seems to be necessary and sufficient to induce a full atrial AP shape in hiPSC-CM in EHT format. RA concentrations are prone to methodological issues and may profoundly impact the success of atrial differentiation.
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Affiliation(s)
- Carl Schulz
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; German Centre for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Muhammed Sönmez
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; German Centre for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Julia Krause
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; German Centre for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany; Department of Cardiology, University Heart and Vascular Center, Hamburg, Germany
| | - Edzard Schwedhelm
- German Centre for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany; Institute of Clinical Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Pan Bangfen
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; German Centre for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Dzenefa Alihodzic
- Hospital Pharmacy, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Arne Hansen
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; German Centre for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Thomas Eschenhagen
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; German Centre for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany.
| | - Torsten Christ
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; German Centre for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany.
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Clark AP, Clerx M, Wei S, Lei CL, de Boer TP, Mirams GR, Christini DJ, Krogh-Madsen T. Leak current, even with gigaohm seals, can cause misinterpretation of stem cell-derived cardiomyocyte action potential recordings. Europace 2023; 25:euad243. [PMID: 37552789 PMCID: PMC10445319 DOI: 10.1093/europace/euad243] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 06/18/2023] [Indexed: 08/10/2023] Open
Abstract
AIMS Human-induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) have become an essential tool to study arrhythmia mechanisms. Much of the foundational work on these cells, as well as the computational models built from the resultant data, has overlooked the contribution of seal-leak current on the immature and heterogeneous phenotype that has come to define these cells. The aim of this study is to understand the effect of seal-leak current on recordings of action potential (AP) morphology. METHODS AND RESULTS Action potentials were recorded in human iPSC-CMs using patch clamp and simulated using previously published mathematical models. Our in silico and in vitro studies demonstrate how seal-leak current depolarizes APs, substantially affecting their morphology, even with seal resistances (Rseal) above 1 GΩ. We show that compensation of this leak current is difficult due to challenges with obtaining accurate measures of Rseal during an experiment. Using simulation, we show that Rseal measures (i) change during an experiment, invalidating the use of pre-rupture values, and (ii) are polluted by the presence of transmembrane currents at every voltage. Finally, we posit that the background sodium current in baseline iPSC-CM models imitates the effects of seal-leak current and is increased to a level that masks the effects of seal-leak current on iPSC-CMs. CONCLUSION Based on these findings, we make recommendations to improve iPSC-CM AP data acquisition, interpretation, and model-building. Taking these recommendations into account will improve our understanding of iPSC-CM physiology and the descriptive ability of models built from such data.
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Affiliation(s)
- Alexander P Clark
- Department of Biomedical Engineering, Cornell University, Ithaca, NY, USA
| | - Michael Clerx
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, Nottingham, UK
| | - Siyu Wei
- Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Chon Lok Lei
- Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Macau, China
- Department of Biomedical Sciences, Faculty of Health Sciences, University of Macau, Macau, China
| | - Teun P de Boer
- Department of Medical Physiology, Division of Heart and Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Gary R Mirams
- Centre for Mathematical Medicine and Biology, School of Mathematical Sciences, University of Nottingham, Nottingham, UK
| | - David J Christini
- Department of Biomedical Engineering, Cornell University, Ithaca, NY, USA
- Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Trine Krogh-Madsen
- Department of Physiology and Biophysics, Weill Cornell Medicine, 1300 York Avenue, Box 75, Room C501D, New York, 10065 NY, USA
- Institute for Computational Biomedicine, Weill Cornell Medicine, 1300 York Avenue, Box 75, Room C501D, New York, 10065 NY, USA
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Ahmad FS, Jin Y, Grassam-Rowe A, Zhou Y, Yuan M, Fan X, Zhou R, Mu-u-min R, O'Shea C, Ibrahim AM, Hyder W, Aguib Y, Yacoub M, Pavlovic D, Zhang Y, Tan X, Lei M, Terrar DA. Generation of cardiomyocytes from human-induced pluripotent stem cells resembling atrial cells with ability to respond to adrenoceptor agonists. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220312. [PMID: 37122218 PMCID: PMC10150206 DOI: 10.1098/rstb.2022.0312] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Accepted: 12/07/2022] [Indexed: 05/02/2023] Open
Abstract
Atrial fibrillation (AF) is the most common chronic arrhythmia presenting a heavy disease burden. We report a new approach for generating cardiomyocytes (CMs) resembling atrial cells from human-induced pluripotent stem cells (hiPSCs) using a combination of Gremlin 2 and retinoic acid treatment. More than 40% of myocytes showed rod-shaped morphology, expression of CM proteins (including ryanodine receptor 2, α-actinin-2 and F-actin) and striated appearance, all of which were broadly similar to the characteristics of adult atrial myocytes (AMs). Isolated myocytes were electrically quiescent until stimulated to fire action potentials with an AM profile and an amplitude of approximately 100 mV, arising from a resting potential of approximately -70 mV. Single-cell RNA sequence analysis showed a high level of expression of several atrial-specific transcripts including NPPA, MYL7, HOXA3, SLN, KCNJ4, KCNJ5 and KCNA5. Amplitudes of calcium transients recorded from spontaneously beating cultures were increased by the stimulation of α-adrenoceptors (activated by phenylephrine and blocked by prazosin) or β-adrenoceptors (activated by isoproterenol and blocked by CGP20712A). Our new approach provides human AMs with mature characteristics from hiPSCs which will facilitate drug discovery by enabling the study of human atrial cell signalling pathways and AF. This article is part of the theme issue 'The heartbeat: its molecular basis and physiological mechanisms'.
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Affiliation(s)
- Faizzan S. Ahmad
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
- Cure8bio, Inc, 395 Fulton Street, Westbury, NY 11590, USA
| | - Yongcheng Jin
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | | | - Yafei Zhou
- Key Laboratory of Medical Electrophysiology of the Ministry of Education and Institute of Cardiovascular Research, Southwest Medical University, Luzhou 6400, People's Republic of China
- Shaanxi Institute for Pediatric Diseases, Department of Cardiology, Xi'an Children's Hospital, Xi'an 710003, People's Republic of China
| | - Meng Yuan
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
- Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057, USA
| | - Xuehui Fan
- Key Laboratory of Medical Electrophysiology of the Ministry of Education and Institute of Cardiovascular Research, Southwest Medical University, Luzhou 6400, People's Republic of China
| | - Rui Zhou
- Key Laboratory of Medical Electrophysiology of the Ministry of Education and Institute of Cardiovascular Research, Southwest Medical University, Luzhou 6400, People's Republic of China
| | - Razik Mu-u-min
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Christopher O'Shea
- Institute of Cardiovascular Sciences, College of Medicine and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Ayman M. Ibrahim
- Aswan Heart Centre, Aswan 1242770, Egypt
- Department of Zoology, Faculty of Science, Cairo University, Cairo 12613, Egypt
| | - Wajiha Hyder
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Yasmine Aguib
- Aswan Heart Centre, Aswan 1242770, Egypt
- National Heart and Lung Institute, Heart Science Centre, Imperial College London, Middlesex SW3 6LY, UK
| | - Magdi Yacoub
- Aswan Heart Centre, Aswan 1242770, Egypt
- National Heart and Lung Institute, Heart Science Centre, Imperial College London, Middlesex SW3 6LY, UK
| | - Davor Pavlovic
- Institute of Cardiovascular Sciences, College of Medicine and Dental Sciences, University of Birmingham, Birmingham B15 2TT, UK
| | - Yanmin Zhang
- Shaanxi Institute for Pediatric Diseases, Department of Cardiology, Xi'an Children's Hospital, Xi'an 710003, People's Republic of China
| | - Xiaoqiu Tan
- Key Laboratory of Medical Electrophysiology of the Ministry of Education and Institute of Cardiovascular Research, Southwest Medical University, Luzhou 6400, People's Republic of China
| | - Ming Lei
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Derek A. Terrar
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
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Ismaili D, Schulz C, Horváth A, Koivumäki JT, Mika D, Hansen A, Eschenhagen T, Christ T. Human induced pluripotent stem cell-derived cardiomyocytes as an electrophysiological model: Opportunities and challenges-The Hamburg perspective. Front Physiol 2023; 14:1132165. [PMID: 36875015 PMCID: PMC9978010 DOI: 10.3389/fphys.2023.1132165] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Accepted: 02/06/2023] [Indexed: 02/18/2023] Open
Abstract
Models based on human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) are proposed in almost any field of physiology and pharmacology. The development of human induced pluripotent stem cell-derived cardiomyocytes is expected to become a step forward to increase the translational power of cardiovascular research. Importantly they should allow to study genetic effects on an electrophysiological background close to the human situation. However, biological and methodological issues revealed when human induced pluripotent stem cell-derived cardiomyocytes were used in experimental electrophysiology. We will discuss some of the challenges that should be considered when human induced pluripotent stem cell-derived cardiomyocytes will be used as a physiological model.
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Affiliation(s)
- Djemail Ismaili
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,Department of Cardiology, University Heart and Vascular Center Hamburg, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Carl Schulz
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - András Horváth
- Translational Cardiology, Department of Cardiology, Inselspital, University Hospital Bern, University of Bern, Bern, Switzerland
| | - Jussi T Koivumäki
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Delphine Mika
- Inserm, UMR-S 1180, Université Paris-Saclay, Orsay, France
| | - Arne Hansen
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Thomas Eschenhagen
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Torsten Christ
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
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Adenosine and Adenosine Receptors: Advances in Atrial Fibrillation. Biomedicines 2022; 10:biomedicines10112963. [PMID: 36428533 PMCID: PMC9687155 DOI: 10.3390/biomedicines10112963] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 11/07/2022] [Accepted: 11/14/2022] [Indexed: 11/19/2022] Open
Abstract
Atrial fibrillation (AF) is the most common arrhythmia in the world. Because the key to developing innovative therapies that limit the onset and the progression of AF is to fully understand the underlying molecular mechanisms of AF, the aim of the present narrative review is to report the most recent advances in the potential role of the adenosinergic system in the pathophysiology of AF. After a comprehensive approach describing adenosinergic system signaling and the mechanisms of the initiation and maintenance of AF, we address the interactions of the adenosinergic system's signaling with AF. Indeed, adenosine release can activate four G-coupled membrane receptors, named A1, A2A, A2B and A3. Activation of the A2A receptors can promote the occurrence of delayed depolarization, while activation of the A1 receptors can shorten the action potential's duration and induce the resting membrane's potential hyperpolarization, which promote pulmonary vein firing, stabilize the AF rotors and allow for functional reentry. Moreover, the A2B receptors have been associated with atrial fibrosis homeostasis. Finally, the adenosinergic system can modulate the autonomous nervous system and is associated with AF risk factors. A question remains regarding adenosine release and the adenosine receptors' activation and whether this would be a cause or consequence of AF.
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Abramochkin DV, Filatova TS, Pustovit KB, Voronina YA, Kuzmin VS, Vornanen M. Ionic currents underlying different patterns of electrical activity in working cardiac myocytes of mammals and non-mammalian vertebrates. Comp Biochem Physiol A Mol Integr Physiol 2022; 268:111204. [PMID: 35346823 DOI: 10.1016/j.cbpa.2022.111204] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/21/2022] [Accepted: 03/22/2022] [Indexed: 12/19/2022]
Abstract
The orderly contraction of the vertebrate heart is determined by generation and propagation of cardiac action potentials (APs). APs are generated by the integrated activity of time- and voltage-dependent ionic channels which carry inward Na+ and Ca2+ currents, and outward K+ currents. This review compares atrial and ventricular APs and underlying ion currents between different taxa of vertebrates. We have collected literature data and attempted to find common electrophysiological features for two or more vertebrate groups, show differences between taxa and cardiac chambers, and indicate gaps in the existing data. Although electrical excitability of the heart in all vertebrates is based on the same superfamily of channels, there is a vast variability of AP waveforms between atrial and ventricular myocytes, between different species of the same vertebrate class and between endothermic and ectothermic animals. The wide variability of AP shapes is related to species-specific differences in animal size, heart rate, stage of ontogenetic development, excitation-contraction coupling, temperature and oxygen availability. Some of the differences between taxa are related to evolutionary development of genomes, which appear e.g. in the expression of different Na+ and K+ channel orthologues in cardiomyocytes of vertebrates. There is a wonderful variability of AP shapes and underlying ion currents with which electrical excitability of vertebrate heart can be generated depending on the intrinsic and extrinsic conditions of animal body. This multitude of ionic mechanisms provides excellent material for studying how the function of the vertebrate heart can adapt or acclimate to prevailing physiological and environmental conditions.
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Affiliation(s)
- Denis V Abramochkin
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia.
| | - Tatiana S Filatova
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia
| | - Ksenia B Pustovit
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia
| | - Yana A Voronina
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia; Laboratory of Cardiac Electrophysiology, National Medical Research Center for Cardiology, 3(rd) Cherepkovskaya str., 15A, Moscow, Russia
| | - Vladislav S Kuzmin
- Department of Human and Animal Physiology, Lomonosov Moscow State University, Leninskiye gory, 1, 12, Moscow 119234, Russia; Department of Physiology, Pirogov Russian National Research Medical University, Ostrovityanova str., 1, Moscow, Russia
| | - Matti Vornanen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland
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9
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Soepriatna AH, Kim TY, Daley MC, Song E, Choi BR, Coulombe KLK. Human Atrial Cardiac Microtissues for Chamber-Specific Arrhythmic Risk Assessment. Cell Mol Bioeng 2021; 14:441-457. [PMID: 34777603 DOI: 10.1007/s12195-021-00703-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 09/02/2021] [Indexed: 01/10/2023] Open
Abstract
Introduction Although atrial fibrillation is the most prevalent disorder of electrical conduction, the mechanisms behind atrial arrhythmias remain elusive. To address this challenge, we developed a robust in vitro model of 3D atrial microtissue from human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes and evaluated chamber-specific chemical responses experimentally and computationally. Methods We differentiated atrial and ventricular cardiomyocytes (aCMs/vCMs) from GCaMP6f-expressing hiPSCs and assessed spontaneous AP activity using fluorescence imaging. Self-assembling 3D microtissues were formed with lactate purified CMs and 5% human cardiac fibroblasts and electrically stimulated for one week before high resolution action potential (AP) optical mapping. AP responses to the atrial-specific potassium repolarizing current I Kur-blocker 4-Aminopyridine (4-AP) and funny current I f-blocker Ivabradine were characterized within their therapeutic window. Finally, we expanded upon a published hiPSC-CM computational model by incorporating the atrial-specific I Kur current, modifying ion channel conductances to match the AP waveforms of our microtissues, and employing the updated model to reinforce our experimental findings. Results High purity CMs (> 75% cTnT+) demonstrated subtype specification by MLC2v expression. Spontaneous beating rates significantly decreased following 3D microtissue formation, with atrial microtissues characterized by their faster spontaneous beating rate, slower AP rise time, and shorter AP duration (APD) compared to ventricular microtissues. We measured atrial-specific responses, including dose-dependent APD prolongation with 4-AP treatment and dose-dependent reduction in spontaneous activity post-Ivabradine treatment. Conclusion The presented in vitro platform for screening atrial-specific responses is both robust and sensitive, with high throughput, enabling studies focused at elucidating the mechanisms underlying atrial arrhythmias. Supplementary Information The online version contains supplementary material available at 10.1007/s12195-021-00703-x.
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Affiliation(s)
- Arvin H Soepriatna
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI USA
| | - Tae Yun Kim
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, RI USA
| | - Mark C Daley
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI USA
| | - Elena Song
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI USA
| | - Bum-Rak Choi
- Cardiovascular Research Center, Cardiovascular Institute, Rhode Island Hospital and Alpert Medical School of Brown University, Providence, RI USA
| | - Kareen L K Coulombe
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI USA
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10
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Jost N, Christ T, Magyar J. New Strategies for the Treatment of Atrial Fibrillation. Pharmaceuticals (Basel) 2021; 14:ph14090926. [PMID: 34577626 PMCID: PMC8466466 DOI: 10.3390/ph14090926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 09/07/2021] [Accepted: 09/08/2021] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in the clinical practice. It significantly contributes to the morbidity and mortality of the elderly population. Over the past 25-30 years intense effort in basic research has advanced the understanding of the relationship between the pathophysiology of AF and atrial remodelling. Nowadays it is clear that the various forms of atrial remodelling (electrical, contractile and structural) play crucial role in initiating and maintaining the persistent and permanent types of AF. Unlike in ventricular fibrillation, in AF rapid ectopic firing originating from pulmonary veins and re-entry mechanism may induce and maintain (due to atrial remodelling) this complex cardiac arrhythmia. The present review presents and discusses in detail the latest knowledge on the role of remodelling in AF. Special attention is paid to novel concepts and pharmacological targets presumably relevant to the drug treatment of atrial fibrillation.
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Affiliation(s)
- Norbert Jost
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, 6725 Szeged, Hungary
- Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, 6725 Szeged, Hungary
- ELKH-SZTE Research Group for Cardiovascular Pharmacology, Eötvös Loránd Research Network, 6725 Szeged, Hungary
- Correspondence:
| | - Torsten Christ
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany;
- DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - János Magyar
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary;
- Department of Sport Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
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11
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Quinazolinone dimers as a potential new class of safer Kv1 inhibitors: Overcoming hERG, sodium and calcium channel affinities. Bioorg Chem 2021; 115:105264. [PMID: 34416509 DOI: 10.1016/j.bioorg.2021.105264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 07/11/2021] [Accepted: 08/07/2021] [Indexed: 11/24/2022]
Abstract
The discovery of more selective and safer voltage-gated potassium channel blockers is an extremely demanding approach. Designing selective Kv1.5 inhibitors is very challenging as only limited data is available on this target due to a lacking crystal structure for this ion channel receptor. Herein, we synthesized a series of 21 novel quinazolinone dimers 3a-i, 5a-i and 10a-c. We tried to avoid structural features responsible for non-selectivity and for most potassium channel blockers' side effects in our design. In contrast to other works, which lack investigation over wide ranges of potassium and sodium channels, we screened the inhibitory activity of our synthesized compounds over multiple voltage-gated potassium channels, including six different human Kv1 channel subtypes Kv1.1, Kv1.2, Kv1.3, Kv1.4, Kv1.5 and Kv1.6 channels as well as Kv2.1, Kv3.1, Kv4.3, Kv7.2, Kv7.3, Kv10.1, hERG, and Shaker IR. Moreover, these compounds' selectivity was investigated on sodium channels Nav1.2, Nav1.4 and Nav1.5 and calcium channels Cav3.1-Cav3.3. The results revealed two compounds (3a and 3e) with low micromolar Kv1.5 inhibition activity with EC50 values of 5.1 ± 0.9 µM and 12.5 ± 1.1 µM, respectively. However, at higher concentrations, they also showed inhibitory activity on Kv1.3 and Kv1.1 channels. This might be due to structural similarities between these three Kv1 channel isoforms. Compound 3a shows a slight preference for Kv1.5. Interestingly, they lack any activity on other potassium channels (including hERG), sodium channels, and calcium channels. Our findings recommend quinazolinone dimers with ethylene linker as a potential new class of safer Kv1 inhibitors and a good start for designing more selective and potent Kv1.5 inhibitors.
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12
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Verkerk AO, Marchal GA, Zegers JG, Kawasaki M, Driessen AHG, Remme CA, de Groot JR, Wilders R. Patch-Clamp Recordings of Action Potentials From Human Atrial Myocytes: Optimization Through Dynamic Clamp. Front Pharmacol 2021; 12:649414. [PMID: 33912059 PMCID: PMC8072333 DOI: 10.3389/fphar.2021.649414] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 02/18/2021] [Indexed: 11/29/2022] Open
Abstract
Introduction: Atrial fibrillation (AF) is the most common cardiac arrhythmia. Consequently, novel therapies are being developed. Ultimately, the impact of compounds on the action potential (AP) needs to be tested in freshly isolated human atrial myocytes. However, the frequent depolarized state of these cells upon isolation seriously hampers reliable AP recordings. Purpose: We assessed whether AP recordings from single human atrial myocytes could be improved by providing these cells with a proper inward rectifier K+ current (IK1), and consequently with a regular, non-depolarized resting membrane potential (RMP), through “dynamic clamp”. Methods: Single myocytes were enzymatically isolated from left atrial appendage tissue obtained from patients with paroxysmal AF undergoing minimally invasive surgical ablation. APs were elicited at 1 Hz and measured using perforated patch-clamp methodology, injecting a synthetic IK1 to generate a regular RMP. The injected IK1 had strong or moderate rectification. For comparison, a regular RMP was forced through injection of a constant outward current. A wide variety of ion channel blockers was tested to assess their modulatory effects on AP characteristics. Results: Without any current injection, RMPs ranged from −9.6 to −86.2 mV in 58 cells. In depolarized cells (RMP positive to −60 mV), RMP could be set at −80 mV using IK1 or constant current injection and APs could be evoked upon stimulation. AP duration differed significantly between current injection methods (p < 0.05) and was shortest with constant current injection and longest with injection of IK1 with strong rectification. With moderate rectification, AP duration at 90% repolarization (APD90) was similar to myocytes with regular non-depolarized RMP, suggesting that a synthetic IK1 with moderate rectification is the most appropriate for human atrial myocytes. Importantly, APs evoked using each injection method were still sensitive to all drugs tested (lidocaine, nifedipine, E-4031, low dose 4-aminopyridine, barium, and apamin), suggesting that the major ionic currents of the atrial cells remained functional. However, certain drug effects were quantitatively dependent on the current injection approach used. Conclusion: Injection of a synthetic IK1 with moderate rectification facilitates detailed AP measurements in human atrial myocytes. Therefore, dynamic clamp represents a promising tool for testing novel antiarrhythmic drugs.
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Affiliation(s)
- Arie O Verkerk
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands.,Department of Experimental Cardiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Gerard A Marchal
- Department of Experimental Cardiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Jan G Zegers
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Makiri Kawasaki
- Department of Experimental Cardiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Antoine H G Driessen
- Department of Cardiothoracic Surgery, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Carol Ann Remme
- Department of Experimental Cardiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Joris R de Groot
- Department of Cardiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Ronald Wilders
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
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13
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Darkow E, Nguyen TT, Stolina M, Kari FA, Schmidt C, Wiedmann F, Baczkó I, Kohl P, Rajamani S, Ravens U, Peyronnet R. Small Conductance Ca 2 +-Activated K + (SK) Channel mRNA Expression in Human Atrial and Ventricular Tissue: Comparison Between Donor, Atrial Fibrillation and Heart Failure Tissue. Front Physiol 2021; 12:650964. [PMID: 33868017 PMCID: PMC8047327 DOI: 10.3389/fphys.2021.650964] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/01/2021] [Indexed: 12/25/2022] Open
Abstract
In search of more efficacious and safe pharmacological treatments for atrial fibrillation (AF), atria-selective antiarrhythmic agents have been promoted that target ion channels principally expressed in the atria. This concept allows one to engage antiarrhythmic effects in atria, but spares the ventricles from potentially proarrhythmic side effects. It has been suggested that cardiac small conductance Ca2+-activated K+ (SK) channels may represent an atria-selective target in mammals including humans. However, there are conflicting data concerning the expression of SK channels in different stages of AF, and recent findings suggest that SK channels are upregulated in ventricular myocardium when patients develop heart failure. To address this issue, RNA-sequencing was performed to compare expression levels of three SK channels (KCNN1, KCNN2, and KCNN3) in human atrial and ventricular tissue samples from transplant donor hearts (no cardiac disease), and patients with cardiac disease in sinus rhythm or with AF. In addition, for control purposes expression levels of several genes known to be either chamber-selective or differentially expressed in AF and heart failure were determined. In atria, as compared to ventricle from transplant donor hearts, we confirmed higher expression of KCNN1 and KCNA5, and lower expression of KCNJ2, whereas KCNN2 and KCNN3 were statistically not differentially expressed. Overall expression of KCNN1 was low compared to KCNN2 and KCNN3. Comparing atrial tissue from patients with AF to sinus rhythm samples we saw downregulation of KCNN2 in AF, as previously reported. When comparing ventricular tissue from heart failure patients to non-diseased samples, we found significantly increased ventricular expression of KCNN3 in heart failure, as previously published. The other channels showed no significant difference in expression in either disease. Our results add weight to the view that SK channels are not likely to be an atria-selective target, especially in failing human hearts, and modulators of these channels may prove to have less utility in treating AF than hoped. Whether targeting SK1 holds potential remains to be elucidated.
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Affiliation(s)
- Elisa Darkow
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Freiburg im Breisgau, Germany.,Medical Center and Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany.,Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg im Breisgau, Germany.,Faculty of Biology, University of Freiburg, Freiburg im Breisgau, Germany
| | - Thong T Nguyen
- Genome Analysis Unit, Amgen Research, Amgen Inc., South San Francisco, CA, United States
| | - Marina Stolina
- Department of Cardiometabolic Disorders, Amgen Research, Amgen Inc., Thousand Oaks, CA, United States
| | - Fabian A Kari
- Medical Center and Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany.,Department of Cardiovascular Surgery, University Heart Center Freiburg-Bad Krozingen, Freiburg im Breisgau, Germany
| | - Constanze Schmidt
- Department of Cardiology, University Hospital Heidelberg, Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research) Partner Site Heidelberg/Mannheim, Heidelberg University, Heidelberg, Germany
| | - Felix Wiedmann
- Department of Cardiology, University Hospital Heidelberg, Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research) Partner Site Heidelberg/Mannheim, Heidelberg University, Heidelberg, Germany
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Freiburg im Breisgau, Germany.,Medical Center and Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany.,CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg im Breisgau, Germany
| | - Sridharan Rajamani
- Translational Safety and Bioanalytical Sciences, Amgen Research, Amgen Inc., South San Francisco, CA, United States
| | - Ursula Ravens
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Freiburg im Breisgau, Germany.,Medical Center and Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
| | - Rémi Peyronnet
- Institute for Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Freiburg im Breisgau, Germany.,Medical Center and Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany
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14
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James EC, Tomaskovic-Crook E, Crook JM. Bioengineering Clinically Relevant Cardiomyocytes and Cardiac Tissues from Pluripotent Stem Cells. Int J Mol Sci 2021; 22:ijms22063005. [PMID: 33809429 PMCID: PMC8001925 DOI: 10.3390/ijms22063005] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 03/11/2021] [Accepted: 03/12/2021] [Indexed: 12/23/2022] Open
Abstract
The regenerative capacity of cardiomyocytes is insufficient to functionally recover damaged tissue, and as such, ischaemic heart disease forms the largest proportion of cardiovascular associated deaths. Human-induced pluripotent stem cells (hiPSCs) have enormous potential for developing patient specific cardiomyocytes for modelling heart disease, patient-based cardiac toxicity testing and potentially replacement therapy. However, traditional protocols for hiPSC-derived cardiomyocytes yield mixed populations of atrial, ventricular and nodal-like cells with immature cardiac properties. New insights gleaned from embryonic heart development have progressed the precise production of subtype-specific hiPSC-derived cardiomyocytes; however, their physiological immaturity severely limits their utility as model systems and their use for drug screening and cell therapy. The long-entrenched challenges in this field are being addressed by innovative bioengingeering technologies that incorporate biophysical, biochemical and more recently biomimetic electrical cues, with the latter having the potential to be used to both direct hiPSC differentiation and augment maturation and the function of derived cardiomyocytes and cardiac tissues by mimicking endogenous electric fields.
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Affiliation(s)
- Emma Claire James
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, AIIM Facility, University of Wollongong, Wollongong 2500, Australia;
| | - Eva Tomaskovic-Crook
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, AIIM Facility, University of Wollongong, Wollongong 2500, Australia;
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong 2500, Australia
- Correspondence: (E.T.-C.); (J.M.C.)
| | - Jeremy Micah Crook
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, AIIM Facility, University of Wollongong, Wollongong 2500, Australia;
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong 2500, Australia
- Department of Surgery, St Vincent’s Hospital, The University of Melbourne, Fitzroy 3065, Australia
- Correspondence: (E.T.-C.); (J.M.C.)
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15
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Varró A, Tomek J, Nagy N, Virág L, Passini E, Rodriguez B, Baczkó I. Cardiac transmembrane ion channels and action potentials: cellular physiology and arrhythmogenic behavior. Physiol Rev 2020; 101:1083-1176. [PMID: 33118864 DOI: 10.1152/physrev.00024.2019] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Cardiac arrhythmias are among the leading causes of mortality. They often arise from alterations in the electrophysiological properties of cardiac cells and their underlying ionic mechanisms. It is therefore critical to further unravel the pathophysiology of the ionic basis of human cardiac electrophysiology in health and disease. In the first part of this review, current knowledge on the differences in ion channel expression and properties of the ionic processes that determine the morphology and properties of cardiac action potentials and calcium dynamics from cardiomyocytes in different regions of the heart are described. Then the cellular mechanisms promoting arrhythmias in congenital or acquired conditions of ion channel function (electrical remodeling) are discussed. The focus is on human-relevant findings obtained with clinical, experimental, and computational studies, given that interspecies differences make the extrapolation from animal experiments to human clinical settings difficult. Deepening the understanding of the diverse pathophysiology of human cellular electrophysiology will help in developing novel and effective antiarrhythmic strategies for specific subpopulations and disease conditions.
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Affiliation(s)
- András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - Jakub Tomek
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Norbert Nagy
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary.,MTA-SZTE Cardiovascular Pharmacology Research Group, Hungarian Academy of Sciences, Szeged, Hungary
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Elisa Passini
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - Blanca Rodriguez
- Department of Computer Science, British Heart Foundation Centre of Research Excellence, University of Oxford, Oxford, United Kingdom
| | - István Baczkó
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
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16
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Hilderink S, Devalla HD, Bosch L, Wilders R, Verkerk AO. Ultrarapid Delayed Rectifier K + Channelopathies in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Front Cell Dev Biol 2020; 8:536. [PMID: 32850774 PMCID: PMC7399090 DOI: 10.3389/fcell.2020.00536] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 06/08/2020] [Indexed: 12/12/2022] Open
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia. About 5-15% of AF patients have a mutation in a cardiac gene, including mutations in KCNA5, encoding the Kv1.5 α-subunit of the ion channel carrying the atrial-specific ultrarapid delayed rectifier K+ current (IKur). Both loss-of-function and gain-of-function AF-related mutations in KCNA5 are known, but their effects on action potentials (APs) of human cardiomyocytes have been poorly studied. Here, we assessed the effects of wild-type and mutant IKur on APs of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). We found that atrial-like hiPSC-CMs, generated by a retinoic acid-based differentiation protocol, have APs with faster repolarization compared to ventricular-like hiPSC-CMs, resulting in shorter APs with a lower AP plateau. Native IKur, measured as current sensitive to 50 μM 4-aminopyridine, was 1.88 ± 0.49 (mean ± SEM, n = 17) and 0.26 ± 0.26 pA/pF (n = 17) in atrial- and ventricular-like hiPSC-CMs, respectively. In both atrial- and ventricular-like hiPSC-CMs, IKur blockade had minimal effects on AP parameters. Next, we used dynamic clamp to inject various amounts of a virtual IKur, with characteristics as in freshly isolated human atrial myocytes, into 11 atrial-like and 10 ventricular-like hiPSC-CMs, in which native IKur was blocked. Injection of IKur with 100% density shortened the APs, with its effect being strongest on the AP duration at 20% repolarization (APD20) of atrial-like hiPSC-CMs. At IKur densities < 100% (compared to 100%), simulating loss-of-function mutations, significant AP prolongation and raise of plateau were observed. At IKur densities > 100%, simulating gain-of-function mutations, APD20 was decreased in both atrial- and ventricular-like hiPSC-CMs, but only upon a strong increase in IKur. In ventricular-like hiPSC-CMs, lowering of the plateau resulted in AP shortening. We conclude that a decrease in IKur, mimicking loss-of-function mutations, has a stronger effect on the AP of hiPSC-CMs than an increase, mimicking gain-of-function mutations, whereas in ventricular-like hiPSC-CMs such increase results in AP shortening, causing their AP morphology to become more atrial-like. Effects of native IKur modulation on atrial-like hiPSC-CMs are less pronounced than effects of virtual IKur injection because IKur density of atrial-like hiPSC-CMs is substantially smaller than that of freshly isolated human atrial myocytes.
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Affiliation(s)
- Sarah Hilderink
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Harsha D Devalla
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Leontien Bosch
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Ronald Wilders
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| | - Arie O Verkerk
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands.,Department of Experimental Cardiology, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
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17
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Platzer D, Zorn-Pauly K. Accuracy considerations for capacitance estimation by voltage steps in cardiomyocytes. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 157:3-10. [PMID: 32217074 DOI: 10.1016/j.pbiomolbio.2020.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 03/03/2020] [Accepted: 03/09/2020] [Indexed: 10/24/2022]
Abstract
Electrophysiologists routinely use simple voltage steps to evaluate cell membrane capacitance derived from corresponding current responses. Frequently, the resting membrane voltage Vrest is employed as holding potential for the subsequent command voltage step and more or less accurate methods are utilised to analyse the transient current. Another choice as holding potential is the peak of the "quasi steady-state" current to voltage relationship, Vpeak. The aim of this study is the systematic evaluation of capacitance estimation accuracy from voltage step experiments depending on the choice of holding potential and analysis method. In this paper, a simulation approach is employed to analyse the current response of a model patch-clamp circuit. Four commonly accepted methods are implemented, utilizing different aspects of the transient current (charge, membrane time constant, and influence of the series resistance) in various combinations and with various degrees of refinement. This simulation study indicates an acceptable accuracy of the elaborated methods for capacitance estimation at holding potentials Vrest and Vpeak over a broad range of capacitance as well as series resistance values. Simple integration of the current transient provides sufficient accuracy at holding potentials, which effectively minimizes changes in resistive membrane current flow during command voltage steps (particularly around Vpeak). However, biphasic command protocols performed at Vpeak activate voltage dependent sodium channels, thereby possibly leading to the threshold voltage for an action potential. Compared to Vrest, all methods utilizing monophasic step protocols, gain additional accuracy, when applied at Vpeak as holding potential.
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Affiliation(s)
- Dieter Platzer
- Chair of Biophysics, Gottfried Schatz Research Center, Medical University Graz, Neue Stiftingtalstraße 6/IV, 8010, Graz, Austria
| | - Klaus Zorn-Pauly
- Chair of Biophysics, Gottfried Schatz Research Center, Medical University Graz, Neue Stiftingtalstraße 6/IV, 8010, Graz, Austria.
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18
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Tazmini K, Frisk M, Lewalle A, Laasmaa M, Morotti S, Lipsett DB, Manfra O, Skogestad J, Aronsen JM, Sejersted OM, Sjaastad I, Edwards AG, Grandi E, Niederer SA, Øie E, Louch WE. Hypokalemia Promotes Arrhythmia by Distinct Mechanisms in Atrial and Ventricular Myocytes. Circ Res 2020; 126:889-906. [PMID: 32070187 PMCID: PMC7098435 DOI: 10.1161/circresaha.119.315641] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
RATIONALE Hypokalemia occurs in up to 20% of hospitalized patients and is associated with increased incidence of ventricular and atrial fibrillation. It is unclear whether these differing types of arrhythmia result from direct and perhaps distinct effects of hypokalemia on cardiomyocytes. OBJECTIVE To investigate proarrhythmic mechanisms of hypokalemia in ventricular and atrial myocytes. METHODS AND RESULTS Experiments were performed in isolated rat myocytes exposed to simulated hypokalemia conditions (reduction of extracellular [K+] from 5.0 to 2.7 mmol/L) and supported by mathematical modeling studies. Ventricular cells subjected to hypokalemia exhibited Ca2+ overload and increased generation of both spontaneous Ca2+ waves and delayed afterdepolarizations. However, similar Ca2+-dependent spontaneous activity during hypokalemia was only observed in a minority of atrial cells that were observed to contain t-tubules. This effect was attributed to close functional pairing of the Na+-K+ ATPase and Na+-Ca2+ exchanger proteins within these structures, as reduction in Na+ pump activity locally inhibited Ca2+ extrusion. Ventricular myocytes and tubulated atrial myocytes additionally exhibited early afterdepolarizations during hypokalemia, associated with Ca2+ overload. However, early afterdepolarizations also occurred in untubulated atrial cells, despite Ca2+ quiescence. These phase-3 early afterdepolarizations were rather linked to reactivation of nonequilibrium Na+ current, as they were rapidly blocked by tetrodotoxin. Na+ current-driven early afterdepolarizations in untubulated atrial cells were enabled by membrane hyperpolarization during hypokalemia and short action potential configurations. Brief action potentials were in turn maintained by ultra-rapid K+ current (IKur); a current which was found to be absent in tubulated atrial myocytes and ventricular myocytes. CONCLUSIONS Distinct mechanisms underlie hypokalemia-induced arrhythmia in the ventricle and atrium but also vary between atrial myocytes depending on subcellular structure and electrophysiology.
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Affiliation(s)
- Kiarash Tazmini
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
- Department of Internal Medicine, Diakonhjemmet Hospital, Oslo, Norway (K.T., E.Ø.)
| | - Michael Frisk
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
- KG Jebsen Center for Cardiac Research (M.F., M.L., O.M., I.S., W.E.L.), University of Oslo, Norway
| | - Alexandre Lewalle
- Division of Imaging Sciences and Biomedical Engineering, King’s College London, United Kingdom (A.L., S.A.N.)
| | - Martin Laasmaa
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
- KG Jebsen Center for Cardiac Research (M.F., M.L., O.M., I.S., W.E.L.), University of Oslo, Norway
| | - Stefano Morotti
- Department of Pharmacology, School of Medicine, University of California Davis (S.M., A.G.E., E.G.)
| | - David B. Lipsett
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
| | - Ornella Manfra
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
- KG Jebsen Center for Cardiac Research (M.F., M.L., O.M., I.S., W.E.L.), University of Oslo, Norway
| | - Jonas Skogestad
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
| | - Jan M. Aronsen
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
- Bjørknes College, Oslo, Norway (J.M.A.)
| | - Ole M. Sejersted
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
| | - Ivar Sjaastad
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
- KG Jebsen Center for Cardiac Research (M.F., M.L., O.M., I.S., W.E.L.), University of Oslo, Norway
| | - Andrew G. Edwards
- Department of Pharmacology, School of Medicine, University of California Davis (S.M., A.G.E., E.G.)
| | - Eleonora Grandi
- Department of Pharmacology, School of Medicine, University of California Davis (S.M., A.G.E., E.G.)
| | - Steven A. Niederer
- Division of Imaging Sciences and Biomedical Engineering, King’s College London, United Kingdom (A.L., S.A.N.)
| | - Erik Øie
- Department of Internal Medicine, Diakonhjemmet Hospital, Oslo, Norway (K.T., E.Ø.)
| | - William E. Louch
- From the Institute for Experimental Medical Research, Oslo University Hospital (K.T., M.F., M.L., D.B.L., O.M., J.S., J.M.A., O.M.S., I.S., W.E.L.), University of Oslo, Norway
- KG Jebsen Center for Cardiac Research (M.F., M.L., O.M., I.S., W.E.L.), University of Oslo, Norway
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Zhao Z, Ruan S, Ma X, Feng Q, Xie Z, Nie Z, Fan P, Qian M, He X, Wu S, Zhang Y, Zheng X. Challenges Faced with Small Molecular Modulators of Potassium Current Channel Isoform Kv1.5. Biomolecules 2019; 10:E10. [PMID: 31861703 PMCID: PMC7022446 DOI: 10.3390/biom10010010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 12/08/2019] [Accepted: 12/10/2019] [Indexed: 12/30/2022] Open
Abstract
The voltage-gated potassium channel Kv1.5, which mediates the cardiac ultra-rapid delayed-rectifier (IKur) current in human cells, has a crucial role in atrial fibrillation. Therefore, the design of selective Kv1.5 modulators is essential for the treatment of pathophysiological conditions involving Kv1.5 activity. This review summarizes the progress of molecular structures and the functionality of different types of Kv1.5 modulators, with a focus on clinical cardiovascular drugs and a number of active natural products, through a summarization of 96 compounds currently widely used. Furthermore, we also discuss the contributions of Kv1.5 and the regulation of the structure-activity relationship (SAR) of synthetic Kv1.5 inhibitors in human pathophysiology. SAR analysis is regarded as a useful strategy in structural elucidation, as it relates to the characteristics that improve compounds targeting Kv1.5. Herein, we present previous studies regarding the structural, pharmacological, and SAR information of the Kv1.5 modulator, through which we can assist in identifying and designing potent and specific Kv1.5 inhibitors in the treatment of diseases involving Kv1.5 activity.
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Affiliation(s)
- Zefeng Zhao
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, 229 Taibai Road, Xi’an 710069, China; (Z.Z.); (S.R.); (X.M.); (Q.F.); (Z.X.); (Z.N.); (P.F.); (Y.Z.); (X.Z.)
- Biomedicine Key Laboratory of Shaanxi Province, School of Pharmacy, Northwest University, 229 Taibai Road, Xi’an 710069, China
| | - Songsong Ruan
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, 229 Taibai Road, Xi’an 710069, China; (Z.Z.); (S.R.); (X.M.); (Q.F.); (Z.X.); (Z.N.); (P.F.); (Y.Z.); (X.Z.)
- Biomedicine Key Laboratory of Shaanxi Province, School of Pharmacy, Northwest University, 229 Taibai Road, Xi’an 710069, China
| | - Xiaoming Ma
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, 229 Taibai Road, Xi’an 710069, China; (Z.Z.); (S.R.); (X.M.); (Q.F.); (Z.X.); (Z.N.); (P.F.); (Y.Z.); (X.Z.)
- Biomedicine Key Laboratory of Shaanxi Province, School of Pharmacy, Northwest University, 229 Taibai Road, Xi’an 710069, China
| | - Qian Feng
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, 229 Taibai Road, Xi’an 710069, China; (Z.Z.); (S.R.); (X.M.); (Q.F.); (Z.X.); (Z.N.); (P.F.); (Y.Z.); (X.Z.)
- Biomedicine Key Laboratory of Shaanxi Province, School of Pharmacy, Northwest University, 229 Taibai Road, Xi’an 710069, China
| | - Zhuosong Xie
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, 229 Taibai Road, Xi’an 710069, China; (Z.Z.); (S.R.); (X.M.); (Q.F.); (Z.X.); (Z.N.); (P.F.); (Y.Z.); (X.Z.)
- Biomedicine Key Laboratory of Shaanxi Province, School of Pharmacy, Northwest University, 229 Taibai Road, Xi’an 710069, China
| | - Zhuang Nie
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, 229 Taibai Road, Xi’an 710069, China; (Z.Z.); (S.R.); (X.M.); (Q.F.); (Z.X.); (Z.N.); (P.F.); (Y.Z.); (X.Z.)
- Biomedicine Key Laboratory of Shaanxi Province, School of Pharmacy, Northwest University, 229 Taibai Road, Xi’an 710069, China
| | - Peinan Fan
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, 229 Taibai Road, Xi’an 710069, China; (Z.Z.); (S.R.); (X.M.); (Q.F.); (Z.X.); (Z.N.); (P.F.); (Y.Z.); (X.Z.)
- Biomedicine Key Laboratory of Shaanxi Province, School of Pharmacy, Northwest University, 229 Taibai Road, Xi’an 710069, China
| | - Mingcheng Qian
- Department of Medicinal Chemistry, School of Pharmaceutical Engineering and Life Science, Changzhou University, Changzhou 213164, China;
- Laboratory for Medicinal Chemistry, Ghent University, Ottergemsesteenweg 460, B-9000 Ghent, Belgium
| | - Xirui He
- Department of Bioengineering, Zhuhai Campus of Zunyi Medical University, Zhuhai 519041, China;
| | - Shaoping Wu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, 229 Taibai Road, Xi’an 710069, China; (Z.Z.); (S.R.); (X.M.); (Q.F.); (Z.X.); (Z.N.); (P.F.); (Y.Z.); (X.Z.)
- Biomedicine Key Laboratory of Shaanxi Province, School of Pharmacy, Northwest University, 229 Taibai Road, Xi’an 710069, China
| | - Yongmin Zhang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, 229 Taibai Road, Xi’an 710069, China; (Z.Z.); (S.R.); (X.M.); (Q.F.); (Z.X.); (Z.N.); (P.F.); (Y.Z.); (X.Z.)
- Biomedicine Key Laboratory of Shaanxi Province, School of Pharmacy, Northwest University, 229 Taibai Road, Xi’an 710069, China
- Sorbonne Université, Institut Parisien de Chimie Moléculaire, CNRS UMR 8232, 4 place Jussieu, 75005 Paris, France
| | - Xiaohui Zheng
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, Northwest University, 229 Taibai Road, Xi’an 710069, China; (Z.Z.); (S.R.); (X.M.); (Q.F.); (Z.X.); (Z.N.); (P.F.); (Y.Z.); (X.Z.)
- Biomedicine Key Laboratory of Shaanxi Province, School of Pharmacy, Northwest University, 229 Taibai Road, Xi’an 710069, China
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20
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Bayer JD, Boukens BJ, Krul SPJ, Roney CH, Driessen AHG, Berger WR, van den Berg NWE, Verkerk AO, Vigmond EJ, Coronel R, de Groot JR. Acetylcholine Delays Atrial Activation to Facilitate Atrial Fibrillation. Front Physiol 2019; 10:1105. [PMID: 31551802 PMCID: PMC6737394 DOI: 10.3389/fphys.2019.01105] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 08/09/2019] [Indexed: 11/13/2022] Open
Abstract
Background Acetylcholine (ACh) shortens action potential duration (APD) in human atria. APD shortening facilitates atrial fibrillation (AF) by reducing the wavelength for reentry. However, the influence of ACh on electrical conduction in human atria and its contribution to AF are unclear, particularly when combined with impaired conduction from interstitial fibrosis. Objective To investigate the effect of ACh on human atrial conduction and its role in AF with computational, experimental, and clinical approaches. Methods S1S2 pacing (S1 = 600 ms and S2 = variable cycle lengths) was applied to the following human AF computer models: a left atrial appendage (LAA) myocyte to quantify the effects of ACh on APD, maximum upstroke velocity (V max ), and resting membrane potential (RMP); a monolayer of LAA myocytes to quantify the effects of ACh on conduction; and 3) an intact left atrium (LA) to determine the effects of ACh on arrhythmogenicity. Heterogeneous ACh and interstitial fibrosis were applied to the monolayer and LA models. To corroborate the simulations, APD and RMP from isolated human atrial myocytes were recorded before and after 0.1 μM ACh. At the tissue level, LAAs from AF patients were optically mapped ex vivo using Di-4-ANEPPS. The difference in total activation time (AT) was determined between AT initially recorded with S1 pacing, and AT recorded during subsequent S1 pacing without (n = 6) or with (n = 7) 100 μM ACh. Results In LAA myocyte simulations, S1 pacing with 0.1 μM ACh shortened APD by 41 ms, hyperpolarized RMP by 7 mV, and increased V max by 27 mV/ms. In human atrial myocytes, 0.1 μM ACh shortened APD by 48 ms, hyperpolarized RMP by 3 mV, and increased V max by 6 mV/ms. In LAA monolayer simulations, S1 pacing with ACh hyperpolarized RMP to delay total AT by 32 ms without and 35 ms with fibrosis. This led to unidirectional conduction block and sustained reentry in fibrotic LA with heterogeneous ACh during S2 pacing. In AF patient LAAs, S1 pacing with ACh increased total AT from 39.3 ± 26 ms to 71.4 ± 31.2 ms (p = 0.036) compared to no change without ACh (56.7 ± 29.3 ms to 50.0 ± 21.9 ms, p = 0.140). Conclusion In fibrotic atria with heterogeneous parasympathetic activation, ACh facilitates AF by shortening APD and slowing conduction to promote unidirectional conduction block and reentry.
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Affiliation(s)
- Jason D Bayer
- Electrophysiology and Heart Modeling Institute (IHU-LIRYC), Bordeaux University Foundation, Bordeaux, France.,Institute of Mathematics of Bordeaux (U5251), University of Bordeaux, Bordeaux, France
| | - Bastiaan J Boukens
- Department of Medical Biology, Academic Medical Center, Amsterdam, Netherlands
| | - Sébastien P J Krul
- Department of Cardiology, Academic Medical Center, Amsterdam, Netherlands
| | - Caroline H Roney
- Division of Imaging Sciences and Bioengineering, King's College London, London, United Kingdom
| | | | - Wouter R Berger
- Department of Cardiology, Academic Medical Center, Amsterdam, Netherlands.,Department of Cardiology, Heart Center, OLVG, Amsterdam, Netherlands
| | | | - Arie O Verkerk
- Department of Medical Biology, Academic Medical Center, Amsterdam, Netherlands.,Department of Experimental Cardiology, Academic Medical Center, Amsterdam, Netherlands
| | - Edward J Vigmond
- Electrophysiology and Heart Modeling Institute (IHU-LIRYC), Bordeaux University Foundation, Bordeaux, France.,Institute of Mathematics of Bordeaux (U5251), University of Bordeaux, Bordeaux, France
| | - Ruben Coronel
- Electrophysiology and Heart Modeling Institute (IHU-LIRYC), Bordeaux University Foundation, Bordeaux, France.,Department of Experimental Cardiology, Academic Medical Center, Amsterdam, Netherlands
| | - Joris R de Groot
- Department of Cardiology, Academic Medical Center, Amsterdam, Netherlands
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21
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Johnson EK, Springer SJ, Wang W, Dranoff EJ, Zhang Y, Kanter EM, Yamada KA, Nerbonne JM. Differential Expression and Remodeling of Transient Outward Potassium Currents in Human Left Ventricles. Circ Arrhythm Electrophysiol 2019; 11:e005914. [PMID: 29311162 DOI: 10.1161/circep.117.005914] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 11/30/2017] [Indexed: 11/16/2022]
Abstract
BACKGROUND Myocardial, transient, outward currents, Ito, have been shown to play pivotal roles in action potential (AP) repolarization and remodeling in animal models. The properties and contribution of Ito to left ventricular (LV) repolarization in the human heart, however, are poorly defined. METHODS AND RESULTS Whole-cell, voltage-clamp recordings, acquired at physiological (35°C to 37°C) temperatures, from myocytes isolated from the LV of nonfailing human hearts identified 2 distinct transient currents, Ito,fast (Ito,f) and Ito,slow (Ito,s), with significantly (P<0.0001) different rates of recovery from inactivation and pharmacological sensitives: Ito,f recovers in ≈10 ms, 100× faster than Ito,s, and is selectively blocked by the Kv4 channel toxin, SNX-482. Current-clamp experiments revealed regional differences in AP waveforms, notably a phase 1 notch in LV subepicardial myocytes. Dynamic clamp-mediated addition/removal of modeled human ventricular Ito,f, resulted in hyperpolarization or depolarization, respectively, of the notch potential, whereas slowing the rate of Ito,f inactivation resulted in AP collapse. AP-clamp experiments demonstrated that changes in notch potentials modified the time course and amplitudes of voltage-gated Ca2+ currents, ICa. In failing LV subepicardial myocytes, Ito,f was reduced and Ito,s was increased, notch and plateau potentials were depolarized (P<0.0001) and AP durations were prolonged (P<0.001). CONCLUSIONS Ito,f and Ito,s are differentially expressed in nonfailing human LV, contributing to regional heterogeneities in AP waveforms. Ito,f regulates notch and plateau potentials and modulates the time course and amplitude of ICa. Slowing Ito,f inactivation results in dramatic AP shortening. Remodeling of Ito,f in failing human LV subepicardial myocytes attenuates transmural differences in AP waveforms.
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Affiliation(s)
- Eric K Johnson
- From the Cardiovascular Division, Department of Medicine (E.K.J., S.J.S., W.W., E.J.D., Y.Z., E.M.K., K.A.Y., J.M.N.) and Department of Developmental Biology (J.M.N.), Washington University School of Medicine, St. Louis, MO
| | - Steven J Springer
- From the Cardiovascular Division, Department of Medicine (E.K.J., S.J.S., W.W., E.J.D., Y.Z., E.M.K., K.A.Y., J.M.N.) and Department of Developmental Biology (J.M.N.), Washington University School of Medicine, St. Louis, MO
| | - Wei Wang
- From the Cardiovascular Division, Department of Medicine (E.K.J., S.J.S., W.W., E.J.D., Y.Z., E.M.K., K.A.Y., J.M.N.) and Department of Developmental Biology (J.M.N.), Washington University School of Medicine, St. Louis, MO
| | - Edward J Dranoff
- From the Cardiovascular Division, Department of Medicine (E.K.J., S.J.S., W.W., E.J.D., Y.Z., E.M.K., K.A.Y., J.M.N.) and Department of Developmental Biology (J.M.N.), Washington University School of Medicine, St. Louis, MO
| | - Yan Zhang
- From the Cardiovascular Division, Department of Medicine (E.K.J., S.J.S., W.W., E.J.D., Y.Z., E.M.K., K.A.Y., J.M.N.) and Department of Developmental Biology (J.M.N.), Washington University School of Medicine, St. Louis, MO
| | - Evelyn M Kanter
- From the Cardiovascular Division, Department of Medicine (E.K.J., S.J.S., W.W., E.J.D., Y.Z., E.M.K., K.A.Y., J.M.N.) and Department of Developmental Biology (J.M.N.), Washington University School of Medicine, St. Louis, MO
| | - Kathryn A Yamada
- From the Cardiovascular Division, Department of Medicine (E.K.J., S.J.S., W.W., E.J.D., Y.Z., E.M.K., K.A.Y., J.M.N.) and Department of Developmental Biology (J.M.N.), Washington University School of Medicine, St. Louis, MO
| | - Jeanne M Nerbonne
- From the Cardiovascular Division, Department of Medicine (E.K.J., S.J.S., W.W., E.J.D., Y.Z., E.M.K., K.A.Y., J.M.N.) and Department of Developmental Biology (J.M.N.), Washington University School of Medicine, St. Louis, MO.
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22
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Long-term 4-AP treatment facilitates functional expression of human Kv1.5 channel. Eur J Pharmacol 2019; 844:195-203. [PMID: 30552904 DOI: 10.1016/j.ejphar.2018.12.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 12/08/2018] [Accepted: 12/11/2018] [Indexed: 11/23/2022]
Abstract
The human Kv1.5 channel (hKv1.5) produces the ultrarapid delayed rectifier potassium current (IKur), which is important for determining the repolarization of action potential in the cardiac atrium. However, the expression of IKur is reduced in patients with chronic atrial fibrillation. 4-Aminopyridine (4-AP) can specifically suppress IKur, suggesting that it modifies hKv1.5 as a chaperone molecule. Herein, the effects of long-term 4-AP treatment on hKv1.5 protein expression and function were investigated in HEK cells. 4-AP treatment (24 h) improved hKv1.5 protein levels, promoted hKv1.5 glycosylation, and facilitated the hKv1.5 current in a time-dependent manner. Long-term 4-AP treatment also markedly enhanced hKv1.5 localization in the cell membrane, endoplasmic reticulum, and Golgi. Importantly, the Ile508 residue located in the hKv1.5 channel pore was found to be important for 4-AP inhibitory activity. These results provide insight into developing hKv1.5 channel blocker that can functionally rescue IKur in patients with chronic atrial fibrillation.
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Bai J, Gladding PA, Stiles MK, Fedorov VV, Zhao J. Ionic and cellular mechanisms underlying TBX5/PITX2 insufficiency-induced atrial fibrillation: Insights from mathematical models of human atrial cells. Sci Rep 2018; 8:15642. [PMID: 30353147 PMCID: PMC6199257 DOI: 10.1038/s41598-018-33958-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 09/24/2018] [Indexed: 12/16/2022] Open
Abstract
Transcription factors TBX5 and PITX2 involve in the regulation of gene expression of ion channels and are closely associated with atrial fibrillation (AF), the most common cardiac arrhythmia in developed countries. The exact cellular and molecular mechanisms underlying the increased susceptibility to AF in patients with TBX5/PITX2 insufficiency remain unclear. In this study, we have developed and validated a novel human left atrial cellular model (TPA) based on the ten Tusscher-Panfilov ventricular cell model to systematically investigate how electrical remodeling induced by TBX5/PITX2 insufficiency leads to AF. Using our TPA model, we have demonstrated that spontaneous diastolic depolarization observed in atrial myocytes with TBX5-deletion can be explained by altered intracellular calcium handling and suppression of inward-rectifier potassium current (IK1). Additionally, our computer simulation results shed new light on the novel cellular mechanism underlying AF by indicating that the imbalance between suppressed outward current IK1 and increased inward sodium-calcium exchanger current (INCX) resulted from SR calcium leak leads to spontaneous depolarizations. Furthermore, our simulation results suggest that these arrhythmogenic triggers can be potentially suppressed by inhibiting sarcoplasmic reticulum (SR) calcium leak and reversing remodeled IK1. More importantly, this study has clinically significant implications on the drugs used for maintaining SR calcium homeostasis, whereby drugs such as dantrolene may confer significant improvement for the treatment of AF patients with TBX5/PITX2 insufficiency.
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Affiliation(s)
- Jieyun Bai
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.
- School of Computer Science and Technology, Harbin Institute Technology, Harbin, China.
| | - Patrick A Gladding
- Department of Cardiology, Waitemata District Health Board, Auckland, New Zealand
| | | | - Vadim V Fedorov
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, United States of America
| | - Jichao Zhao
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.
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Denham NC, Pearman CM, Caldwell JL, Madders GWP, Eisner DA, Trafford AW, Dibb KM. Calcium in the Pathophysiology of Atrial Fibrillation and Heart Failure. Front Physiol 2018; 9:1380. [PMID: 30337881 PMCID: PMC6180171 DOI: 10.3389/fphys.2018.01380] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 09/11/2018] [Indexed: 12/20/2022] Open
Abstract
Atrial fibrillation (AF) is commonly associated with heart failure. A bidirectional relationship exists between the two-AF exacerbates heart failure causing a significant increase in heart failure symptoms, admissions to hospital and cardiovascular death, while pathological remodeling of the atria as a result of heart failure increases the risk of AF. A comprehensive understanding of the pathophysiology of AF is essential if we are to break this vicious circle. In this review, the latest evidence will be presented showing a fundamental role for calcium in both the induction and maintenance of AF. After outlining atrial electrophysiology and calcium handling, the role of calcium-dependent afterdepolarizations and atrial repolarization alternans in triggering AF will be considered. The atrial response to rapid stimulation will be discussed, including the short-term protection from calcium overload in the form of calcium signaling silencing and the eventual progression to diastolic calcium leak causing afterdepolarizations and the development of an electrical substrate that perpetuates AF. The role of calcium in the bidirectional relationship between heart failure and AF will then be covered. The effects of heart failure on atrial calcium handling that promote AF will be reviewed, including effects on both atrial myocytes and the pulmonary veins, before the aspects of AF which exacerbate heart failure are discussed. Finally, the limitations of human and animal studies will be explored allowing contextualization of what are sometimes discordant results.
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Affiliation(s)
- Nathan C. Denham
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | | | | | | | | | | | - Katharine M. Dibb
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
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25
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Colman MA, Saxena P, Kettlewell S, Workman AJ. Description of the Human Atrial Action Potential Derived From a Single, Congruent Data Source: Novel Computational Models for Integrated Experimental-Numerical Study of Atrial Arrhythmia Mechanisms. Front Physiol 2018; 9:1211. [PMID: 30245635 PMCID: PMC6137999 DOI: 10.3389/fphys.2018.01211] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 08/13/2018] [Indexed: 11/13/2022] Open
Abstract
Introduction: The development of improved diagnosis, management, and treatment strategies for human atrial fibrillation (AF) is a significant and important challenge in order to improve quality of life for millions and reduce the substantial social-economic costs of the condition. As a complex condition demonstrating high variability and relation to other cardiac conditions, the study of AF requires approaches from multiple disciplines including single-cell experimental electrophysiology and computational modeling. Models of human atrial cells are less well parameterized than those of the human ventricle or other mammal species, largely due to the inherent challenges in patch clamping human atrial cells. Such challenges include, frequently, unphysiologically depolarized resting potentials and thus injection of a compensatory hyperpolarizing current, as well as detecting certain ion currents which may be disrupted by the cell isolation process. The aim of this study was to develop a laboratory specific model of human atrial electrophysiology which reproduces exactly the conditions of isolated-cell experiments, including testing of multiple experimental interventions. Methods: Formulations for the primary ion currents characterized by isolated-cell experiments in the Workman laboratory were fit directly to voltage-clamp data; the fast sodium-current was parameterized based on experiments relating resting membrane potential to maximal action potential upstroke velocity; compensatory hyperpolarizing current was included as a constant applied current. These formulations were integrated with three independent human atrial cell models to provide a family of novel models. Extrapolated intact-cell models were developed through removal of the hyperpolarizing current and introduction of terminal repolarization potassium currents. Results: The isolated-cell models quantitatively reproduced experimentally measured properties of excitation in both control and pharmacological and dynamic-clamp interventions. Comparison of isolated and intact-cell models highlighted the importance of reproducing this cellular environment when comparing experimental and simulation data. Conclusion: We have developed a laboratory specific model of the human atrial cell which directly reproduces the experimental isolated-cell conditions and captures human atrial excitation properties. The model may be particularly useful for directly relating model to experiment, and offers a complementary tool to the available set of human atrial cell models with specific advantages resulting from the congruent input data source.
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Affiliation(s)
- Michael A Colman
- Leeds Computational Physiology Lab, School of Biomedical Sciences, University of Leeds, Leeds, United Kingdom
| | - Priyanka Saxena
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Sarah Kettlewell
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Antony J Workman
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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26
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Rat atrial engineered heart tissue: a new in vitro model to study atrial biology. Basic Res Cardiol 2018; 113:41. [DOI: 10.1007/s00395-018-0701-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 08/27/2018] [Indexed: 10/28/2022]
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27
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Ma D, Liu Z, Loh LJ, Zhao Y, Li G, Liew R, Islam O, Wu J, Chung YY, Teo WS, Ching CK, Tan BY, Chong D, Ho KL, Lim P, Yong RYY, Panama BK, Kaplan AD, Bett GCL, Ware J, Bezzina CR, Verkerk AO, Cook SA, Rasmusson RL, Wei H. Identification of an I Na-dependent and I to-mediated proarrhythmic mechanism in cardiomyocytes derived from pluripotent stem cells of a Brugada syndrome patient. Sci Rep 2018; 8:11246. [PMID: 30050137 PMCID: PMC6062539 DOI: 10.1038/s41598-018-29574-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 07/16/2018] [Indexed: 02/08/2023] Open
Abstract
Brugada syndrome (BrS) is an inherited cardiac arrhythmia commonly associated with SCN5A mutations, yet its ionic mechanisms remain unclear due to a lack of cellular models. Here, we used human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) from a BrS patient (BrS1) to evaluate the roles of Na+ currents (INa) and transient outward K+ currents (Ito) in BrS induced action potential (AP) changes. To understand the role of these current changes in repolarization we employed dynamic clamp to “electronically express” IK1 and restore normal resting membrane potentials and allow normal recovery of the inactivating currents, INa, ICa and Ito. HiPSC-CMs were generated from BrS1 with a compound SCN5A mutation (p. A226V & p. R1629X) and a healthy sibling control (CON1). Genome edited hiPSC-CMs (BrS2) with a milder p. T1620M mutation and a commercial control (CON2) were also studied. CON1, CON2 and BrS2, had unaltered peak INa amplitudes, and normal APs whereas BrS1, with over 75% loss of INa, displayed a loss-of-INa basal AP morphology (at 1.0 Hz) manifested by a reduced maximum upstroke velocity (by ~80%, p < 0.001) and AP amplitude (p < 0.001), and an increased phase-1 repolarization pro-arrhythmic AP morphology (at 0.1 Hz) in ~25% of cells characterized by marked APD shortening (~65% shortening, p < 0.001). Moreover, Ito densities of BrS1 and CON1 were comparable and increased from 1.0 Hz to 0.1 Hz by ~ 100%. These data indicate that a repolarization deficit could be a mechanism underlying BrS.
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Affiliation(s)
- Dongrui Ma
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore
| | - Zhenfeng Liu
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore
| | - Li Jun Loh
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore
| | - Yongxing Zhao
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore
| | - Guang Li
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore
| | - Reginald Liew
- Cardiovascular & Metabolic Disorders Program, Duke-NUS Medical School Singapore, Singapore, 169857, Republic of Singapore
| | - Omedul Islam
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore
| | - Jianjun Wu
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore
| | - Ying Ying Chung
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore
| | - Wee Siong Teo
- Department of Cardiology, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore
| | - Chi Keong Ching
- Department of Cardiology, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore
| | - Boon Yew Tan
- Department of Cardiology, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore
| | - Daniel Chong
- Department of Cardiology, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore
| | - Kah Leng Ho
- Department of Cardiology, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore
| | - Paul Lim
- Department of Cardiology, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore
| | - Rita Yu Yin Yong
- Defense Medical and Environmental Research Institute, DSO National Laboratories, Singapore, 117510, Republic of Singapore
| | - Brian K Panama
- University at Buffalo, State University of New York, Buffalo, NY, 14214, USA
| | - Aaron D Kaplan
- University at Buffalo, State University of New York, Buffalo, NY, 14214, USA
| | - Glenna C L Bett
- University at Buffalo, State University of New York, Buffalo, NY, 14214, USA
| | - James Ware
- Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Connie R Bezzina
- Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Arie O Verkerk
- Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Stuart A Cook
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore.,Cardiovascular & Metabolic Disorders Program, Duke-NUS Medical School Singapore, Singapore, 169857, Republic of Singapore.,Imperial College London, South Kensington Campus, London, SW7 2AZ, UK
| | - Randall L Rasmusson
- University at Buffalo, State University of New York, Buffalo, NY, 14214, USA.
| | - Heming Wei
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore, 169609, Republic of Singapore. .,Cardiovascular & Metabolic Disorders Program, Duke-NUS Medical School Singapore, Singapore, 169857, Republic of Singapore.
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28
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Cyganek L, Tiburcy M, Sekeres K, Gerstenberg K, Bohnenberger H, Lenz C, Henze S, Stauske M, Salinas G, Zimmermann WH, Hasenfuss G, Guan K. Deep phenotyping of human induced pluripotent stem cell-derived atrial and ventricular cardiomyocytes. JCI Insight 2018; 3:99941. [PMID: 29925689 DOI: 10.1172/jci.insight.99941] [Citation(s) in RCA: 166] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 05/17/2018] [Indexed: 12/20/2022] Open
Abstract
Generation of homogeneous populations of subtype-specific cardiomyocytes (CMs) derived from human induced pluripotent stem cells (iPSCs) and their comprehensive phenotyping is crucial for a better understanding of the subtype-related disease mechanisms and as tools for the development of chamber-specific drugs. The goals of this study were to apply a simple and efficient method for differentiation of iPSCs into defined functional CM subtypes in feeder-free conditions and to obtain a comprehensive understanding of the molecular, cell biological, and functional properties of atrial and ventricular iPSC-CMs on both the single-cell and engineered heart muscle (EHM) level. By a stage-specific activation of retinoic acid signaling in monolayer-based and well-defined culture, we showed that cardiac progenitors can be directed towards a highly homogeneous population of atrial CMs. By combining the transcriptome and proteome profiling of the iPSC-CM subtypes with functional characterizations via optical action potential and calcium imaging, and with contractile analyses in EHM, we demonstrated that atrial and ventricular iPSC-CMs and -EHM highly correspond to the atrial and ventricular heart muscle, respectively. This study provides a comprehensive understanding of the molecular and functional identities characteristic of atrial and ventricular iPSC-CMs and -EHM and supports their suitability in disease modeling and chamber-specific drug screening.
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Affiliation(s)
- Lukas Cyganek
- Clinic for Cardiology and Pneumology, University Medical Center Göttingen (UMG), Göttingen, Germany.,DZHK (German Center for Cardiovascular Research), partner site Göttingen, Germany
| | - Malte Tiburcy
- DZHK (German Center for Cardiovascular Research), partner site Göttingen, Germany.,Institute of Pharmacology and Toxicology, UMG, Göttingen, Germany
| | - Karolina Sekeres
- Institute of Pharmacology and Toxicology, Technische Universität Dresden, Dresden, Germany
| | - Kathleen Gerstenberg
- Clinic for Cardiology and Pneumology, University Medical Center Göttingen (UMG), Göttingen, Germany
| | | | - Christof Lenz
- Institute for Clinical Chemistry, UMG, Göttingen, Germany.,Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Sarah Henze
- Clinic for Cardiology and Pneumology, University Medical Center Göttingen (UMG), Göttingen, Germany
| | - Michael Stauske
- Clinic for Cardiology and Pneumology, University Medical Center Göttingen (UMG), Göttingen, Germany.,DZHK (German Center for Cardiovascular Research), partner site Göttingen, Germany
| | - Gabriela Salinas
- Transcriptome and Genome Analysis Laboratory Core Unit, UMG, Göttingen, Germany
| | - Wolfram-Hubertus Zimmermann
- DZHK (German Center for Cardiovascular Research), partner site Göttingen, Germany.,Institute of Pharmacology and Toxicology, UMG, Göttingen, Germany
| | - Gerd Hasenfuss
- Clinic for Cardiology and Pneumology, University Medical Center Göttingen (UMG), Göttingen, Germany.,DZHK (German Center for Cardiovascular Research), partner site Göttingen, Germany
| | - Kaomei Guan
- Clinic for Cardiology and Pneumology, University Medical Center Göttingen (UMG), Göttingen, Germany.,DZHK (German Center for Cardiovascular Research), partner site Göttingen, Germany.,Institute of Pharmacology and Toxicology, Technische Universität Dresden, Dresden, Germany
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29
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Horváth A, Lemoine MD, Löser A, Mannhardt I, Flenner F, Uzun AU, Neuber C, Breckwoldt K, Hansen A, Girdauskas E, Reichenspurner H, Willems S, Jost N, Wettwer E, Eschenhagen T, Christ T. Low Resting Membrane Potential and Low Inward Rectifier Potassium Currents Are Not Inherent Features of hiPSC-Derived Cardiomyocytes. Stem Cell Reports 2018; 10:822-833. [PMID: 29429959 PMCID: PMC5918194 DOI: 10.1016/j.stemcr.2018.01.012] [Citation(s) in RCA: 76] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 01/12/2018] [Accepted: 01/15/2018] [Indexed: 11/18/2022] Open
Abstract
Human induced pluripotent stem cell (hiPSC) cardiomyocytes (CMs) show less negative resting membrane potential (RMP), which is attributed to small inward rectifier currents (IK1). Here, IK1 was measured in hiPSC-CMs (proprietary and commercial cell line) cultured as monolayer (ML) or 3D engineered heart tissue (EHT) and, for direct comparison, in CMs from human right atrial (RA) and left ventricular (LV) tissue. RMP was measured in isolated cells and intact tissues. IK1 density in ML- and EHT-CMs from the proprietary line was similar to LV and RA, respectively. IK1 density in EHT-CMs from the commercial line was 2-fold smaller than in the proprietary line. RMP in EHT of both lines was similar to RA and LV. Repolarization fraction and IK,ACh response discriminated best between RA and LV and indicated predominantly ventricular phenotype in hiPSC-CMs/EHT. The data indicate that IK1 is not necessarily low in hiPSC-CMs, and technical issues may underlie low RMP in hiPSC-CMs.
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Affiliation(s)
- András Horváth
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany; Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, 6721 Szeged, Hungary
| | - Marc D Lemoine
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; Department of Cardiology-Electrophysiology, University Heart Center Hamburg, 20246 Hamburg, Germany
| | - Alexandra Löser
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Ingra Mannhardt
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Frederik Flenner
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Ahmet Umur Uzun
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Christiane Neuber
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Kaja Breckwoldt
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Arne Hansen
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Evaldas Girdauskas
- Department of Cardiovascular Surgery, University Heart Center Hamburg, 20246 Hamburg, Germany
| | - Hermann Reichenspurner
- Department of Cardiovascular Surgery, University Heart Center Hamburg, 20246 Hamburg, Germany
| | - Stephan Willems
- Department of Cardiology-Electrophysiology, University Heart Center Hamburg, 20246 Hamburg, Germany
| | - Norbert Jost
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, 6721 Szeged, Hungary
| | - Erich Wettwer
- Institute of Pharmacology, University Duisburg-Essen, 45122 Essen, Germany
| | - Thomas Eschenhagen
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Torsten Christ
- Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Institut für Experimentelle Pharmakologie und Toxikologie, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany.
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30
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Han BN, Liang TT, Keen LJ, Fan TT, Zhang XD, Xu L, Zhao Q, Wang SP, Lin HW. Two Marine Cyanobacterial Aplysiatoxin Polyketides, Neo-debromoaplysiatoxin A and B, with K+ Channel Inhibition Activity. Org Lett 2018; 20:578-581. [DOI: 10.1021/acs.orglett.7b03672] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Bing-Nan Han
- Department
of Development Technology of Marine Resources, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou 310018, China
- Research
Center for Marine Drugs, State Key Laboratory of Oncogenes and Related
Genes, Department of Pharmacy, Ren Ji Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
| | - Ting-Ting Liang
- School
of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418, China
| | - Lawrence Jordan Keen
- Department
of Development Technology of Marine Resources, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Ting-Ting Fan
- Department
of Development Technology of Marine Resources, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Xiao-Dan Zhang
- Department
of Development Technology of Marine Resources, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Lin Xu
- Department
of Development Technology of Marine Resources, College of Life Sciences, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Qi Zhao
- Faculty
of Health Sciences, University of Macau, Macau, China
| | - Shu-Ping Wang
- Research
Center for Marine Drugs, State Key Laboratory of Oncogenes and Related
Genes, Department of Pharmacy, Ren Ji Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
| | - Hou-Wen Lin
- Research
Center for Marine Drugs, State Key Laboratory of Oncogenes and Related
Genes, Department of Pharmacy, Ren Ji Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
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31
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Vysotskaya Z, Chidipi B, Rodgers JL, Tang X, Samal E, Kolliputi N, Mohapatra S, Bennett ES, Panguluri SK. Elevated potassium outward currents in hyperoxia treated atrial cardiomyocytes. J Cell Physiol 2017; 233:4317-4326. [PMID: 29139549 DOI: 10.1002/jcp.26263] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 10/09/2017] [Indexed: 12/18/2022]
Abstract
Supplementation of 100% oxygen is a very common intervention in intensive care units (ICU) and critical care centers for patients with dysfunctional lung and lung disorders. Although there is advantage in delivering sufficient levels of oxygen, hyperoxia is reported to be directly associated with increasing in-hospital deaths. Our previous studies reported ventricular and electrical remodeling in hyperoxia treated mouse hearts, and in this article, for the first time, we are investigating the effects of hyperoxia on atrial electrophysiology using whole-cell patch-clamp electrophysiology experiments along with assessment of Kv1.5, Kv4.2, and KChIP2 transcripts and protein profiles using real-time quantitative RT-PCR and Western blotting. Our data showed that induction of hyperoxia for 3 days in mice showed larger outward potassium currents with shorter action potential durations (APD). This increase in current densities is due to significant increase in ultrarapid delayed rectifier outward K+ currents (IKur ) and rapidly activating, rapidly inactivating transient outward K+ current (Ito ) densities. We also observed a significant increase in both transcripts and protein levels of Kv1.5 and KChIP2 in hyperoxia treated atrial cardiomyocytes, whereas no significant change was observed in Kv4.2 transcripts or protein. The data presented here further support our previous findings that hyperoxia induces not only ventricular remodeling, but also atrial electrical remodeling.
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Affiliation(s)
- Zhanna Vysotskaya
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Bojjibabu Chidipi
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Jennifer L Rodgers
- Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, Tampa, Florida
| | - Xiaolan Tang
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Eva Samal
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Narasaiah Kolliputi
- Division of Allergy and Immunology, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Subhra Mohapatra
- Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, Tampa, Florida
| | - Eric S Bennett
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Siva K Panguluri
- Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, Tampa, Florida
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32
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Ni H, Whittaker DG, Wang W, Giles WR, Narayan SM, Zhang H. Synergistic Anti-arrhythmic Effects in Human Atria with Combined Use of Sodium Blockers and Acacetin. Front Physiol 2017; 8:946. [PMID: 29218016 PMCID: PMC5703742 DOI: 10.3389/fphys.2017.00946] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 11/08/2017] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia. Developing effective and safe anti-AF drugs remains an unmet challenge. Simultaneous block of both atrial-specific ultra-rapid delayed rectifier potassium (K+) current (IKur) and the Na+ current (INa) has been hypothesized to be anti-AF, without inducing significant QT prolongation and ventricular side effects. However, the antiarrhythmic advantage of simultaneously blocking these two channels vs. individual block in the setting of AF-induced electrical remodeling remains to be documented. Furthermore, many IKur blockers such as acacetin and AVE0118, partially inhibit other K+ currents in the atria. Whether this multi-K+-block produces greater anti-AF effects compared with selective IKur-block has not been fully understood. The aim of this study was to use computer models to (i) assess the impact of multi-K+-block as exhibited by many IKur blokers, and (ii) evaluate the antiarrhythmic effect of blocking IKur and INa, either alone or in combination, on atrial and ventricular electrical excitation and recovery in the setting of AF-induced electrical-remodeling. Contemporary mathematical models of human atrial and ventricular cells were modified to incorporate dose-dependent actions of acacetin (a multichannel blocker primarily inhibiting IKur while less potently blocking Ito, IKr, and IKs). Rate- and atrial-selective inhibition of INa was also incorporated into the models. These single myocyte models were then incorporated into multicellular two-dimensional (2D) and three-dimensional (3D) anatomical models of the human atria. As expected, application of IKur blocker produced pronounced action potential duration (APD) prolongation in atrial myocytes. Furthermore, combined multiple K+-channel block that mimicked the effects of acacetin exhibited synergistic APD prolongations. Synergistically anti-AF effects following inhibition of INa and combined IKur/K+-channels were also observed. The attainable maximal AF-selectivity of INa inhibition was greatly augmented by blocking IKur or multiple K+-currents in the atrial myocytes. This enhanced anti-arrhythmic effects of combined block of Na+- and K+-channels were also seen in 2D and 3D simulations; specially, there was an enhanced efficacy in terminating re-entrant excitation waves, exerting improved antiarrhythmic effects in the human atria as compared to a single-channel block. However, in the human ventricular myocytes and tissue, cellular repolarization and computed QT intervals were modestly affected in the presence of actions of acacetin and INa blockers (either alone or in combination). In conclusion, this study demonstrates synergistic antiarrhythmic benefits of combined block of IKur and INa, as well as those of INa and combined multi K+-current block of acacetin, without significant alterations of ventricular repolarization and QT intervals. This approach may be a valuable strategy for the treatment of AF.
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Affiliation(s)
- Haibo Ni
- Biological Physics Group, University of Manchester, Manchester, United Kingdom.,Space Institute of Southern China, Shenzhen, China.,Key Laboratory of Medical Electrophysiology, Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease/Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Dominic G Whittaker
- Biological Physics Group, University of Manchester, Manchester, United Kingdom
| | - Wei Wang
- Biological Physics Group, University of Manchester, Manchester, United Kingdom
| | - Wayne R Giles
- Faculties of Kinesiology and Medicine, University of Calgary, Calgary, AB, Canada
| | - Sanjiv M Narayan
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, United States
| | - Henggui Zhang
- Biological Physics Group, University of Manchester, Manchester, United Kingdom.,Space Institute of Southern China, Shenzhen, China.,Key Laboratory of Medical Electrophysiology, Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease/Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China.,School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
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33
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Ellinwood N, Dobrev D, Morotti S, Grandi E. In Silico Assessment of Efficacy and Safety of I Kur Inhibitors in Chronic Atrial Fibrillation: Role of Kinetics and State-Dependence of Drug Binding. Front Pharmacol 2017; 8:799. [PMID: 29163179 PMCID: PMC5681918 DOI: 10.3389/fphar.2017.00799] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 10/23/2017] [Indexed: 12/14/2022] Open
Abstract
Current pharmacological therapy against atrial fibrillation (AF), the most common cardiac arrhythmia, is limited by moderate efficacy and adverse side effects including ventricular proarrhythmia and organ toxicity. One way to circumvent the former is to target ion channels that are predominantly expressed in atria vs. ventricles, such as KV1.5, carrying the ultra-rapid delayed-rectifier K+ current (IKur). Recently, we used an in silico strategy to define optimal KV1.5-targeting drug characteristics, including kinetics and state-dependent binding, that maximize AF-selectivity in human atrial cardiomyocytes in normal sinus rhythm (nSR). However, because of evidence for IKur being strongly diminished in long-standing persistent (chronic) AF (cAF), the therapeutic potential of drugs targeting IKur may be limited in cAF patients. Here, we sought to simulate the efficacy (and safety) of IKur inhibitors in cAF conditions. To this end, we utilized sensitivity analysis of our human atrial cardiomyocyte model to assess the importance of IKur for atrial cardiomyocyte electrophysiological properties, simulated hundreds of theoretical drugs to reveal those exhibiting anti-AF selectivity, and compared the results obtained in cAF with those in nSR. We found that despite being downregulated, IKur contributes more prominently to action potential (AP) and effective refractory period (ERP) duration in cAF vs. nSR, with ideal drugs improving atrial electrophysiology (e.g., ERP prolongation) more in cAF than in nSR. Notably, the trajectory of the AP during cAF is such that more IKur is available during the more depolarized plateau potential. Furthermore, IKur block in cAF has less cardiotoxic effects (e.g., AP duration not exceeding nSR values) and can increase Ca2+ transient amplitude thereby enhancing atrial contractility. We propose that in silico strategies such as that presented here should be combined with in vitro and in vivo assays to validate model predictions and facilitate the ongoing search for novel agents against AF.
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Affiliation(s)
- Nicholas Ellinwood
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Dobromir Dobrev
- West German Heart and Vascular Center, Institute of Pharmacology, University Duisburg-Essen, Essen, Germany
| | - Stefano Morotti
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
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34
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Jeevaratnam K, Chadda KR, Huang CLH, Camm AJ. Cardiac Potassium Channels: Physiological Insights for Targeted Therapy. J Cardiovasc Pharmacol Ther 2017; 23:119-129. [PMID: 28946759 PMCID: PMC5808825 DOI: 10.1177/1074248417729880] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The development of novel drugs specifically directed at the ion channels underlying particular features of cardiac action potential (AP) initiation, recovery, and refractoriness would contribute to an optimized approach to antiarrhythmic therapy that minimizes potential cardiac and extracardiac toxicity. Of these, K+ channels contribute numerous and diverse currents with specific actions on different phases in the time course of AP repolarization. These features and their site-specific distribution make particular K+ channel types attractive therapeutic targets for the development of pharmacological agents attempting antiarrhythmic therapy in conditions such as atrial fibrillation. However, progress in the development of such temporally and spatially selective antiarrhythmic drugs against particular ion channels has been relatively limited, particularly in view of our incomplete understanding of the complex physiological roles and interactions of the various ionic currents. This review summarizes the physiological properties of the main cardiac potassium channels and the way in which they modulate cardiac electrical activity and then critiques a number of available potential antiarrhythmic drugs directed at them.
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Affiliation(s)
- Kamalan Jeevaratnam
- 1 Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,2 School of Medicine, Perdana University-Royal College of Surgeons Ireland, Serdang, Selangor Darul Ehsan, Malaysia
| | - Karan R Chadda
- 1 Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,3 Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Christopher L-H Huang
- 3 Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.,4 Division of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - A John Camm
- 5 Cardiac Clinical Academic Group, St George's Hospital Medical School, University of London, Cranmer Terrace, London, United Kingdom
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35
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Juhász V, Hornyik T, Benák A, Nagy N, Husti Z, Pap R, Sághy L, Virág L, Varró A, Baczkó I. Comparison of the effects of I K,ACh, I Kr, and I Na block in conscious dogs with atrial fibrillation and on action potentials in remodeled atrial trabeculae. Can J Physiol Pharmacol 2017; 96:18-25. [PMID: 28892643 DOI: 10.1139/cjpp-2017-0342] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and a major cause of morbidity and mortality. Traditional antiarrhythmic agents used for restoration of sinus rhythm have limited efficacy in long-term AF and they may possess ventricular proarrhythmic adverse effects, especially in patients with structural heart disease. The acetylcholine receptor-activated potassium channel (IK,ACh) represents an atrial selective target for future AF management. We investigated the effects of the IK,ACh blocker tertiapin-Q (TQ), a derivative of the honeybee toxin tertiapin, on chronic atrial tachypacing-induced AF in conscious dogs, without the influence of anesthetics that modulate a number of cardiac ion channels. Action potentials (APs) were recorded from right atrial trabeculae isolated from dogs with AF. TQ significantly and dose-dependently reduced AF incidence and AF episode duration, prolonged atrial effective refractory period, and prolonged AP duration. The reference drugs propafenone and dofetilide, both used in the clinical management of AF, exerted similar effects against AF in vivo. Dofetilide prolonged atrial AP duration, whereas propafenone increased atrial conduction time. TQ and propafenone did not affect the QT interval, whereas dofetilide prolonged the QT interval. Our results show that inhibition of IK,ACh may represent a novel, atrial-specific target for the management of AF in chronic AF.
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Affiliation(s)
- Viktor Juhász
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Tibor Hornyik
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Attila Benák
- b 2nd Department of Internal Medicine and Cardiology Centre, University of Szeged, Szeged, Hungary
| | - Norbert Nagy
- c MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - Zoltán Husti
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Róbert Pap
- b 2nd Department of Internal Medicine and Cardiology Centre, University of Szeged, Szeged, Hungary
| | - László Sághy
- b 2nd Department of Internal Medicine and Cardiology Centre, University of Szeged, Szeged, Hungary
| | - László Virág
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - András Varró
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary.,c MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - István Baczkó
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
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36
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Ellinwood N, Dobrev D, Morotti S, Grandi E. Revealing kinetics and state-dependent binding properties of I Kur-targeting drugs that maximize atrial fibrillation selectivity. CHAOS (WOODBURY, N.Y.) 2017; 27:093918. [PMID: 28964116 PMCID: PMC5573366 DOI: 10.1063/1.5000226] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 07/06/2017] [Indexed: 06/07/2023]
Abstract
The KV1.5 potassium channel, which underlies the ultra-rapid delayed-rectifier current (IKur) and is predominantly expressed in atria vs. ventricles, has emerged as a promising target to treat atrial fibrillation (AF). However, while numerous KV1.5-selective compounds have been screened, characterized, and tested in various animal models of AF, evidence of antiarrhythmic efficacy in humans is still lacking. Moreover, current guidelines for pre-clinical assessment of candidate drugs heavily rely on steady-state concentration-response curves or IC50 values, which can overlook adverse cardiotoxic effects. We sought to investigate the effects of kinetics and state-dependent binding of IKur-targeting drugs on atrial electrophysiology in silico and reveal the ideal properties of IKur blockers that maximize anti-AF efficacy and minimize pro-arrhythmic risk. To this aim, we developed a new Markov model of IKur that describes KV1.5 gating based on experimental voltage-clamp data in atrial myocytes from patient right-atrial samples in normal sinus rhythm. We extended the IKur formulation to account for state-specificity and kinetics of KV1.5-drug interactions and incorporated it into our human atrial cell model. We simulated 1- and 3-Hz pacing protocols in drug-free conditions and with a [drug] equal to the IC50 value. The effects of binding and unbinding kinetics were determined by examining permutations of the forward (kon) and reverse (koff) binding rates to the closed, open, and inactivated states of the KV1.5 channel. We identified a subset of ideal drugs exhibiting anti-AF electrophysiological parameter changes at fast pacing rates (effective refractory period prolongation), while having little effect on normal sinus rhythm (limited action potential prolongation). Our results highlight that accurately accounting for channel interactions with drugs, including kinetics and state-dependent binding, is critical for developing safer and more effective pharmacological anti-AF options.
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Affiliation(s)
- Nicholas Ellinwood
- Department of Pharmacology, University of California Davis, Davis, California 95616, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis, California 95616, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California 95616, USA
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37
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Verkerk AO, Veerman CC, Zegers JG, Mengarelli I, Bezzina CR, Wilders R. Patch-Clamp Recording from Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes: Improving Action Potential Characteristics through Dynamic Clamp. Int J Mol Sci 2017; 18:ijms18091873. [PMID: 28867785 PMCID: PMC5618522 DOI: 10.3390/ijms18091873] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 08/22/2017] [Accepted: 08/22/2017] [Indexed: 01/10/2023] Open
Abstract
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) hold great promise for studying inherited cardiac arrhythmias and developing drug therapies to treat such arrhythmias. Unfortunately, until now, action potential (AP) measurements in hiPSC-CMs have been hampered by the virtual absence of the inward rectifier potassium current (IK1) in hiPSC-CMs, resulting in spontaneous activity and altered function of various depolarising and repolarising membrane currents. We assessed whether AP measurements in "ventricular-like" and "atrial-like" hiPSC-CMs could be improved through a simple, highly reproducible dynamic clamp approach to provide these cells with a substantial IK1 (computed in real time according to the actual membrane potential and injected through the patch-clamp pipette). APs were measured at 1 Hz using perforated patch-clamp methodology, both in control cells and in cells treated with all-trans retinoic acid (RA) during the differentiation process to increase the number of cells with atrial-like APs. RA-treated hiPSC-CMs displayed shorter APs than control hiPSC-CMs and this phenotype became more prominent upon addition of synthetic IK1 through dynamic clamp. Furthermore, the variability of several AP parameters decreased upon IK1 injection. Computer simulations with models of ventricular-like and atrial-like hiPSC-CMs demonstrated the importance of selecting an appropriate synthetic IK1. In conclusion, the dynamic clamp-based approach of IK1 injection has broad applicability for detailed AP measurements in hiPSC-CMs.
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Affiliation(s)
- Arie O Verkerk
- Department of Medical Biology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
- Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Christiaan C Veerman
- Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Jan G Zegers
- Department of Medical Biology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Isabella Mengarelli
- Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Connie R Bezzina
- Department of Experimental Cardiology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
| | - Ronald Wilders
- Department of Medical Biology, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands.
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38
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Aguilar M, Feng J, Vigmond E, Comtois P, Nattel S. Rate-Dependent Role of I Kur in Human Atrial Repolarization and Atrial Fibrillation Maintenance. Biophys J 2017; 112:1997-2010. [PMID: 28494969 DOI: 10.1016/j.bpj.2017.03.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 03/06/2017] [Accepted: 03/23/2017] [Indexed: 11/24/2022] Open
Abstract
The atrial-specific ultrarapid delayed rectifier K+ current (IKur) inactivates slowly but completely at depolarized voltages. The consequences for IKur rate-dependence have not been analyzed in detail and currently available mathematical action-potential (AP) models do not take into account experimentally observed IKur inactivation dynamics. Here, we developed an updated formulation of IKur inactivation that accurately reproduces time-, voltage-, and frequency-dependent inactivation. We then modified the human atrial cardiomyocyte Courtemanche AP model to incorporate realistic IKur inactivation properties. Despite markedly different inactivation dynamics, there was no difference in AP parameters across a wide range of stimulation frequencies between the original and updated models. Using the updated model, we showed that, under physiological stimulation conditions, IKur does not inactivate significantly even at high atrial rates because the transmembrane potential spends little time at voltages associated with inactivation. Thus, channel dynamics are determined principally by activation kinetics. IKur magnitude decreases at higher rates because of AP changes that reduce IKur activation. Nevertheless, the relative contribution of IKur to AP repolarization increases at higher frequencies because of reduced activation of the rapid delayed-rectifier current IKr. Consequently, IKur block produces dose-dependent termination of simulated atrial fibrillation (AF) in the absence of AF-induced electrical remodeling. The inclusion of AF-related ionic remodeling stabilizes simulated AF and greatly reduces the predicted antiarrhythmic efficacy of IKur block. Our results explain a range of experimental observations, including recently reported positive rate-dependent IKur-blocking effects on human atrial APs, and provide insights relevant to the potential value of IKur as an antiarrhythmic target for the treatment of AF.
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Affiliation(s)
- Martin Aguilar
- Research Center, Montreal Heart Institute, Université de Montréal, Montreal, Québec, Canada; Department of Pharmacology and Physiology/Institute of Biomedical Engineering, Université de Montréal, Montreal, Québec, Canada
| | | | - Edward Vigmond
- L'Institut de Rythmologie et Modélisation Cardiaque LIRYC, Fondation Université de Bordeaux, Hôpital Xavier-Arnozan, Pessac, France; Institut de Mathématiques de Bordeaux, Université de Bordeaux, Talence, France
| | - Philippe Comtois
- Research Center, Montreal Heart Institute, Université de Montréal, Montreal, Québec, Canada; Department of Pharmacology and Physiology/Institute of Biomedical Engineering, Université de Montréal, Montreal, Québec, Canada
| | - Stanley Nattel
- Research Center, Montreal Heart Institute, Université de Montréal, Montreal, Québec, Canada; Department of Medicine, McGill University, Montreal, Québec, Canada; Department of Pharmacology and Therapeutics, McGill University, Montreal, Québec, Canada; Department of Medicine, Université de Montréal, Montreal, Québec, Canada; West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany.
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39
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Gunaga P, Lloyd J, Mummadi S, Banerjee A, Dhondi NK, Hennan J, Subray V, Jayaram R, Rajugowda N, Umamaheshwar Reddy K, Kumaraguru D, Mandal U, Beldona D, Adisechen AK, Yadav N, Warrier J, Johnson JA, Sale H, Putlur SP, Saxena A, Chimalakonda A, Mandlekar S, Conder M, Xing D, Gupta AK, Gupta A, Rampulla R, Mathur A, Levesque P, Wexler RR, Finlay HJ. Selective I Kur Inhibitors for the Potential Treatment of Atrial Fibrillation: Optimization of the Phenyl Quinazoline Series Leading to Clinical Candidate 5-[5-Phenyl-4-(pyridin-2-ylmethylamino)quinazolin-2-yl]pyridine-3-sulfonamide. J Med Chem 2017; 60:3795-3803. [PMID: 28418664 DOI: 10.1021/acs.jmedchem.6b01889] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We have recently disclosed 5-phenyl-N-(pyridin-2-ylmethyl)-2-(pyrimidin-5-yl)quinazolin-4-amine 1 as a potent IKur current blocker with selectivity versus hERG, Na and Ca channels, and an acceptable preclinical PK profile. Upon further characterization in vivo, compound 1 demonstrated an unacceptable level of brain penetration. In an effort to reduce the level of brain penetration while maintaining the overall profile, SAR was developed at the C2' position for a series of close analogues by employing hydrogen bond donors. As a result, 5-[5-phenyl-4-(pyridin-2-ylmethylamino)quinazolin-2-yl]pyridine-3-sulfonamide (25) was identified as the lead compound in this series. Compound 25 showed robust effects in rabbit and canine pharmacodynamic models and an acceptable cross-species pharmacokinetic profile and was advanced as the clinical candidate. Further optimization of 25 to mitigate pH-dependent absorption resulted in identification of the corresponding phosphoramide prodrug (29) with an improved solubility and pharmacokinetic profile.
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Affiliation(s)
- Prashantha Gunaga
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - John Lloyd
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Somanadham Mummadi
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Abhisek Banerjee
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Naveen Kumar Dhondi
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - James Hennan
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Veena Subray
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Ramya Jayaram
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Nagendra Rajugowda
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Kommuri Umamaheshwar Reddy
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Duraimurugan Kumaraguru
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Umasankar Mandal
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Dasthagiri Beldona
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Ashok Kumar Adisechen
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Navnath Yadav
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Jayakumar Warrier
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - James A Johnson
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Harinath Sale
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Siva Prasad Putlur
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Ajay Saxena
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Anjaneya Chimalakonda
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Sandhya Mandlekar
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - MaryLee Conder
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Dezhi Xing
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Arun Kumar Gupta
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Anuradha Gupta
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Richard Rampulla
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Arvind Mathur
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Paul Levesque
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Ruth R Wexler
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
| | - Heather J Finlay
- Department of Discovery Chemistry, ‡Department of Biology, and §Department of Pharmaceutical Candidate Optimization, Bristol-Myers Squibb, Research and Development , P.O. Box 5400, Princeton, New Jersey 08543-5400, United States.,Department of Discovery Chemistry, Department of Biology, @Department of Biopharmaceutics, #Department of Pharmaceutical Candidate Optimization, and ∇Biocon BMS R&D Center, Syngene International Limited, BMS India Pvt. Limited , Biocon Park, Jigani Link Road, Bommasandra IV, Bangalore 560099, India
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Tse G, Chan YWF, Keung W, Yan BP. Electrophysiological mechanisms of long and short QT syndromes. IJC HEART & VASCULATURE 2017; 14:8-13. [PMID: 28382321 PMCID: PMC5368285 DOI: 10.1016/j.ijcha.2016.11.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 11/19/2016] [Indexed: 12/21/2022]
Abstract
The QT interval on the human electrocardiogram is normally in the order of 450 ms, and reflects the summated durations of action potential (AP) depolarization and repolarization of ventricular myocytes. Both prolongation and shortening in the QT interval have been associated with ventricular tachy-arrhythmias, which predispose affected individuals to sudden cardiac death. In this article, the molecular determinants of the AP duration and the causes of long and short QT syndromes (LQTS and SQTS) are explored. This is followed by a review of the recent advances on their arrhythmogenic mechanisms involving reentry and/or triggered activity based on experiments conducted in mouse models. Established and novel clinical risk markers based on the QT interval for the prediction of arrhythmic risk and cardiovascular mortality are presented here. It is concluded by a discussion on strategies for the future rational design of anti-arrhythmic agents.
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Affiliation(s)
- Gary Tse
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, SAR, PR China
| | - Yin Wah Fiona Chan
- Department of Psychology, School of Biological Sciences, University of Cambridge, Cambridge, United Kingdom
| | - Wendy Keung
- Stem Cell & Regenerative Medicine Consortium, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, SAR, PR China
| | - Bryan P Yan
- Department of Medicine and Therapeutics, Chinese University of Hong Kong, Hong Kong, SAR, PR China
- Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, VIC, Australia
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41
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Benson M, Iñiguez-Lluhí JA, Martens J. Sumo Modification of Ion Channels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 963:127-141. [PMID: 28197910 DOI: 10.1007/978-3-319-50044-7_8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Recently, a role for SUMO modification outside of the nucleus has emerged. Although the number of extranuclear proteins known to be sumoylated is comparatively small, ion channels represent one important new class of these proteins. Ion channels are responsible for the control of membrane excitability and therefore are critical for fundamental physiological processes such as muscle contraction, neuronal firing, and cellular homeostasis. As such, these ion-conducting proteins are subject to precise regulation. Recently, several studies have identified sumoylation as a novel mechanism of modulating ion channel function. These studies expand the list of known functions of sumoylation and reveal that, in addition to its more established role in the regulation of nuclear proteins, this modification plays important roles at the cytoplasmic face of membranes.
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Affiliation(s)
- Mark Benson
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA
| | | | - Jeffrey Martens
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, USA.
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42
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Kirsch GE, Obejero-Paz CA, Bruening-Wright A. Functional Characterization of Human Stem Cell-Derived Cardiomyocytes. ACTA ACUST UNITED AC 2016; 64:11.12.1-26. [PMID: 25152802 DOI: 10.1002/0471141755.ph1112s64] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Cardiac toxicity is a leading contributor to late-stage attrition in the drug discovery process and to withdrawal of approved from the market. In vitro assays that enable earlier and more accurate testing for cardiac risk provide early stage predictive indicators that aid in mitigating risk. Human cardiomyocytes, the most relevant subjects for early stage testing, are severely limited in supply. But human stem cell-derived cardiomyocytes (SC-hCM) are readily available from commercial sources and are increasingly used in academic research, drug discovery and safety pharmacology. As a result, SC-hCM electrophysiology has become a valuable tool to assess cardiac risk associated with drugs. This unit describes techniques for recording individual currents carried by sodium, calcium and potassium ions, as well as single cell action potentials, and impedance recordings from contracting syncytia of thousands of interconnected cells.
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Dubó S, Gallegos D, Cabrera L, Sobrevia L, Zúñiga L, González M. Cardiovascular Action of Insulin in Health and Disease: Endothelial L-Arginine Transport and Cardiac Voltage-Dependent Potassium Channels. Front Physiol 2016; 7:74. [PMID: 27014078 PMCID: PMC4791397 DOI: 10.3389/fphys.2016.00074] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 02/15/2016] [Indexed: 12/19/2022] Open
Abstract
Impairment of insulin signaling on diabetes mellitus has been related to cardiovascular dysfunction, heart failure, and sudden death. In human endothelium, cationic amino acid transporter 1 (hCAT-1) is related to the synthesis of nitric oxide (NO) and insulin has a vascular effect in endothelial cells through a signaling pathway that involves increases in hCAT-1 expression and L-arginine transport. This mechanism is disrupted in diabetes, a phenomenon potentiated by excessive accumulation of reactive oxygen species (ROS), which contribute to lower availability of NO and endothelial dysfunction. On the other hand, electrical remodeling in cardiomyocytes is considered a key factor in heart failure progression associated to diabetes mellitus. This generates a challenge to understand the specific role of insulin and the pathways involved in cardiac function. Studies on isolated mammalian cardiomyocytes have shown prolongated action potential in ventricular repolarization phase that produces a long QT interval, which is well explained by attenuation in the repolarizing potassium currents in cardiac ventricles. Impaired insulin signaling causes specific changes in these currents, such a decrease amplitude of the transient outward K(+) (Ito) and the ultra-rapid delayed rectifier (IKur) currents where, together, a reduction of mRNA and protein expression levels of α-subunits (Ito, fast; Kv 4.2 and IKs; Kv 1.5) or β-subunits (KChIP2 and MiRP) of K(+) channels involved in these currents in a MAPK mediated pathway process have been described. These results support the hypothesis that lack of insulin signaling can produce an abnormal repolarization in cardiomyocytes. Furthermore, the arrhythmogenic potential due to reduced Ito current can contribute to an increase in the incidence of sudden death in heart failure. This review aims to show, based on pathophysiological models, the regulatory function that would have insulin in vascular system and in cardiac electrophysiology.
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Affiliation(s)
- Sebastián Dubó
- Department of Kinesiology, Faculty of Medicine, Universidad de Concepción Concepción, Chile
| | - David Gallegos
- Vascular Physiology Laboratory, Department of Physiology, Faculty of Biological Sciences, Universidad de Concepción Concepción, Chile
| | - Lissette Cabrera
- Vascular Physiology Laboratory, Department of Physiology, Faculty of Biological Sciences, Universidad de ConcepciónConcepción, Chile; Department of Morphophysiology, Faculty of Medicine, Universidad Diego PortalesSantiago, Chile
| | - Luis Sobrevia
- Cellular and Molecular Physiology Laboratory (CMPL), Division of Obstetrics and Gynecology, Faculty of Medicine, School of Medicine, Pontificia Universidad Católica de ChileSantiago, Chile; Department of Physiology, Faculty of Pharmacy, Universidad de SevillaSeville, Spain; Faculty of Medicine and Biomedical Sciences, University of Queensland Centre for Clinical Research (UQCCR), University of QueenslandHerston, QLD, Queensland, Australia
| | - Leandro Zúñiga
- Centro de Investigaciones Médicas, Escuela de Medicina, Universidad de Talca Talca, Chile
| | - Marcelo González
- Vascular Physiology Laboratory, Department of Physiology, Faculty of Biological Sciences, Universidad de ConcepciónConcepción, Chile; Group of Research and Innovation in Vascular Health (GRIVAS-Health)Chillán, Chile
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Abstract
The voltage gated Kv1.5 channels conduct the ultrarapid delayed rectifier current (IKur) and play critical role in repolarization of action potential duration. It is the most rapidly activated channel and has very little or no inactivated states. In human cardiac cells, these channels are expressed more extensively in atrial myocytes than ventricle. From the evidences of its localization and functions, Kv1.5 has been declared a selective drug target for the treatment of atrial fibrillation (AF). In this present study, we have tried to identify the rapidly activating property of Kv1.5 and studied its mode of inhibition using molecular modeling, docking, and simulation techniques. Channel in open conformation is found to be stabilized quickly within the dipalmitoylphosphatidylcholine membrane, whereas most of the secondary structure elements were lost in closed state conformation. The obvious reason behind its ultra-rapid property is possibly due to the amino acid alteration in S4-S5 linker; the replacement of Lysine by Glutamine and vice versa. The popular published drugs as well as newly identified lead molecules were able to inhibit the Kv1.5 in a very similar pattern, mainly through the nonpolar interactions, and formed sable complexes. V512 is found as the main contributor for the interaction along with the other important residues such as V505, I508, A509, V512, P513, and V516. Furthermore, two screened novel compounds show surprisingly better inhibitory potency and can be considered for the future perspective of antiarrhythmic survey.
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Affiliation(s)
- Rajabrata Bhuyan
- a BIF Centre, Department of Biochemistry & Biophysics , University of Kalyani , Nadia, Kalyani 741235 , West Bengal , India
| | - Alpana Seal
- b Department of Biochemistry & Biophysics , University of Kalyani , Nadia, Kalyani 741235 , West Bengal , India
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Abstract
Blood circulation is the result of the beating of the heart, which provides the mechanical force to pump oxygenated blood to, and deoxygenated blood away from, the peripheral tissues. This depends critically on the preceding electrical activation. Disruptions in the orderly pattern of this propagating cardiac excitation wave can lead to arrhythmias. Understanding of the mechanisms underlying their generation and maintenance requires knowledge of the ionic contributions to the cardiac action potential, which is discussed in the first part of this review. A brief outline of the different classification systems for arrhythmogenesis is then provided, followed by a detailed discussion for each mechanism in turn, highlighting recent advances in this area.
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Amar A, Zlochiver S, Barnea O. Multiscale Interactions in a 3D Model of the Contracting Ventricle. Cardiovasc Eng Technol 2015; 6:401-11. [PMID: 26577475 DOI: 10.1007/s13239-015-0247-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 09/25/2015] [Indexed: 12/01/2022]
Abstract
A biophysical detailed multiscale model of the myocardium is presented. The model was used to study the contribution of interrelated cellular mechanisms to global myocardial function. The multiscale model integrates cellular electrophysiology, excitation propagation dynamics and force development models into a geometrical fiber based model of the ventricle. The description of the cellular electrophysiology in this study was based on the Ten Tusscher-Noble-Noble-Panfilov heterogeneous model for human ventricular myocytes. A four-state model of the sarcomeric control of contraction developed by Negroni and Lascano was employed to model the intracellular mechanism of force generation. The propagation of electrical excitation was described by a reaction-diffusion equation. The 3D geometrical model of the ventricle, based on single fiber contraction was used as a platform for the evaluation of proposed models. The model represents the myocardium as an anatomically oriented array of contracting fibers with individual fiber parameters such as size, spatial location, orientation and mechanical properties. Moreover, the contracting ventricle model interacts with intraventricular blood elements linking the contractile elements to the heart's preload and afterload, thereby producing the corresponding pressure-volume loop. The results show that the multiscale ventricle model is capable of simulating mechanical contraction, pressure generation and load interactions as well as demonstrating the individual contribution of each ion current.
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Affiliation(s)
- Ani Amar
- Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Sharon Zlochiver
- Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Ofer Barnea
- Department of Biomedical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv, 69978, Israel.
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Ford J, Milnes J, El Haou S, Wettwer E, Loose S, Matschke K, Tyl B, Round P, Ravens U. The positive frequency-dependent electrophysiological effects of the IKur inhibitor XEN-D0103 are desirable for the treatment of atrial fibrillation. Heart Rhythm 2015; 13:555-64. [PMID: 26455450 PMCID: PMC4768384 DOI: 10.1016/j.hrthm.2015.10.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Indexed: 11/11/2022]
Abstract
Background Selective inhibitors of Kv1.5 channels are being developed for the treatment of atrial fibrillation (AF). Objectives The purpose of this study was to investigate the effects of the highly selective Kv1.5 inhibitor XEN-D0103 on human atrial action potentials (APs) at high excitation rates and to assess safety. Methods Intracellular APs (stimulation rates 1–5 Hz) were measured in right atrial trabeculae from patients in sinus rhythm (SR), chronic AF (cAF; AF of >6 months duration), and paroxysmal AF (pAF). The safety and tolerability of XEN-D0103 were tested in a double-blind, randomized, placebo-controlled phase 1 study. Results Depending on its concentration, XEN-D0103 elevated the plateau potential. At 1 Hz, XEN-D0103 (3 µM) shortened action potential duration at 90% repolarization (APD90) and effective refractory period (ERP) in SR preparations, but prolonged these parameters in cAF preparations. In SR and pAF preparations, the shortening effects on APD90 and ERP turned into prolongation at high rates. In cAF trabeculae, XEN-D0103 prolonged APD90 and ERP at 2 and 3 Hz. At high rates, more SR and pAF preparations failed to capture excitation in the presence of the drug than in its absence. XEN-D0103 (10 µM) did not significantly affect human ventricular APs. Even with plasma concentrations reaching 7000 ng/mL, XEN-D0103 did not increase ∆∆QTcF (QT interval corrected by the Fridericia formula) in the analysis of electrocardiograms of healthy volunteers, and no subjects receiving an active treatment had a QT or QTcF interval >450 ms, or increase in QTcF from baseline >30 ms. Conclusion APD prolongation and suppression of APs by XEN-D0103 at high stimulation rates in SR and pAF tissue, but not cAF, could be of therapeutic benefit for reducing AF burden. This concept needs to be confirmed in clinical trials.
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Affiliation(s)
- John Ford
- Xention Ltd, Cambridge, United Kingdom
| | | | | | - Erich Wettwer
- Department of Pharmacology and Toxicology, Medical Faculty Carl Gustav Carus, Dresden, Germany
| | - Simone Loose
- Department of Pharmacology and Toxicology, Medical Faculty Carl Gustav Carus, Dresden, Germany
| | - Klaus Matschke
- Clinic for Cardiac Surgery, Heart Center Dresden, Dresden, Germany
| | - Benoit Tyl
- Institut de Recherches Internationales Servier, Suresnes, France
| | | | - Ursula Ravens
- Department of Pharmacology and Toxicology, Medical Faculty Carl Gustav Carus, Dresden, Germany.
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49
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Abstract
Optimal cardiac function depends on proper timing of excitation and contraction in various regions of the heart, as well as on appropriate heart rate. This is accomplished via specialized electrical properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Here we review the major regionally determined electrical properties of these cardiac regions and present the available data regarding the molecular and ionic bases of regional cardiac function and dysfunction. Understanding these differences is of fundamental importance for the investigation of arrhythmia mechanisms and pharmacotherapy.
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Affiliation(s)
- Daniel C Bartos
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, Davis, California, USA
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50
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Turnow K, Metzner K, Cotella D, Morales MJ, Schaefer M, Christ T, Ravens U, Wettwer E, Kämmerer S. Interaction of DPP10a with Kv4.3 channel complex results in a sustained current component of human transient outward current Ito. Basic Res Cardiol 2015; 110:5. [PMID: 25600224 DOI: 10.1007/s00395-014-0457-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 11/21/2014] [Accepted: 12/09/2014] [Indexed: 01/19/2023]
Abstract
The sustained component of the K(+) outward current in human atrial myocytes is believed to be due to the slowly inactivating ultra-rapid potassium current I Kur and not to the fast inactivating transient outward current Ito. Here we provide evidence for contribution of Ito to this late current due to the effects of dipeptidyl peptidase-like protein (DPP) 10 (DPP10a) interacting with Kv4.3 channels. We studied the late current component of Ito in human atrial myocytes and CHO cells co-expressing Kv4.3 or Kv4.3/KChIP2 (control) and DPP proteins using voltage-clamp technique and a pharmacological approach. A voltage dependent and slowly inactivating late current (43% of peak amplitude) could be observed in atrial myocytes. We found a similar current in CHO cells expressing Kv4.3/KChIP2 + DPP10a, but not in cells co-expressing Kv4.3 + DPP or Kv4.3/KChIP2 + DPP6-S. Assuming that DPP10a influences atrial Ito, we detected DPP10 expression of three alternatively spliced mRNAs, DPP10 protein and colocalization of Kv4.3 and DPP10 proteins in human atrial myocytes. DPP10a did not affect properties of expressed Kv1.5 excluding a contribution to the sustained IKur in atrial cells. To test for the contribution of Kv4-based Ito on sustained K(+) outward currents in human atrial myocytes, we used 4-AP to block IKur, in combination with Heteropoda toxin 2 to block Kv4 channels. We could clearly separate an Ito fraction of about 19% contributing to the late current in atrial myocytes. Thus, the interaction of DPP10a, expressed in human atrium, with Kv4.3 channels generates a sustained current component of Ito, which may affect late repolarization phase of atrial action potentials.
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Affiliation(s)
- K Turnow
- Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany
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