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Scranton K, John S, Angelini M, Steccanella F, Umar S, Zhang R, Goldhaber JI, Olcese R, Ottolia M. Cardiac function is regulated by the sodium-dependent inhibition of the sodium-calcium exchanger NCX1. Nat Commun 2024; 15:3831. [PMID: 38714663 PMCID: PMC11076594 DOI: 10.1038/s41467-024-47850-z] [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: 04/13/2022] [Accepted: 04/15/2024] [Indexed: 05/10/2024] Open
Abstract
The Na+-Ca2+ exchanger (NCX1) is the dominant Ca2+ extrusion mechanism in cardiac myocytes. NCX1 activity is inhibited by intracellular Na+ via a process known as Na+-dependent inactivation. A central question is whether this inactivation plays a physiological role in heart function. Using CRISPR/Cas9, we inserted the K229Q mutation in the gene (Slc8a1) encoding for NCX1. This mutation removes the Na+-dependent inactivation while preserving transport properties and other allosteric regulations. NCX1 mRNA levels, protein expression, and protein localization are unchanged in K229Q male mice. However, they exhibit reduced left ventricular ejection fraction and fractional shortening, while displaying a prolonged QT interval. K229Q ventricular myocytes show enhanced NCX1 activity, resulting in action potential prolongation, higher incidence of aberrant action potentials, a faster decline of Ca2+ transients, and depressed cell shortening. The results demonstrate that NCX1 Na+-dependent inactivation plays an essential role in heart function by affecting both cardiac excitability and contractility.
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Affiliation(s)
- Kyle Scranton
- Department of Anesthesiology & Perioperative Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Scott John
- Department of Medicine, Division of Cardiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Marina Angelini
- Department of Anesthesiology & Perioperative Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Federica Steccanella
- Department of Anesthesiology & Perioperative Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Soban Umar
- Department of Anesthesiology & Perioperative Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Rui Zhang
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Joshua I Goldhaber
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Riccardo Olcese
- Department of Anesthesiology & Perioperative Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Michela Ottolia
- Department of Anesthesiology & Perioperative Medicine, Division of Molecular Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA.
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Velez Rueda AJ, Gonano LA, Smith AG, Parisi G, Fornasari MS, Sommese LM. CardIAP: calcium transients confocal image analysis tool. FRONTIERS IN BIOINFORMATICS 2023; 3:1137815. [PMID: 37521316 PMCID: PMC10381969 DOI: 10.3389/fbinf.2023.1137815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 06/23/2023] [Indexed: 08/01/2023] Open
Abstract
One of the main topics of cardiovascular research is the study of calcium (Ca2+) handling, as even small changes in Ca2+ concentration can alter cell functionality (Bers, Annu Rev Physiol, 2014, 76, 107-127). Ionic calcium (Ca2+) plays the role of a second messenger in eukaryotic cells, associated with cellular functions such as cell cycle regulation, transport, motility, gene expression, and regulation. The use of fluorometric techniques in isolated cells loaded with Ca2+-sensitive fluorescent probes allows quantitative measurement of dynamic events occurring in living, functioning cells. The Cardiomyocytes Images Analyzer Python (CardIAP) application addresses the need to analyze and retrieve information from confocal microscopy images systematically, accurately, and rapidly. Here we present CardIAP, an open-source tool developed entirely in Python, freely available and useable in an interactive web application. In addition, CardIAP can be used as a standalone Python library and freely installed via PIP, making it easy to integrate into biomedical imaging pipelines. The images that can be generated in the study of the heart have the particularity of requiring both spatial and temporal analysis. CardIAP aims to open the field of cardiomyocytes and intact hearts image processing. The improvement in the extraction of information from the images will allow optimizing the usage of resources and animals. With CardIAP, users can run the analysis to both, the complete image, and portions of it in an easy way, and replicate it on a series of images. This analysis provides users with information on the spatial and temporal changes in calcium releases and characterizes them. The web application also allows users to extract calcium dynamics data in downloadable tables, simplifying the calculation of alternation and discordance indices and their classification. CardIAP aims to provide a tool that could assist biomedical researchers in studying the underlying mechanisms of anomalous calcium release phenomena.
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Affiliation(s)
- Ana Julia Velez Rueda
- Departamento de Ciencia y Tecnología, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
| | - Luis Alberto Gonano
- Centro de Investigaciones Cardiovasculares, Facultad de Medicina, CONICET, Universidad Nacional de La Plata, La Plata, Argentina
| | - Agustín García Smith
- Departamento de Ciencia y Tecnología, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
| | - Gustavo Parisi
- Departamento de Ciencia y Tecnología, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
| | - María Silvina Fornasari
- Departamento de Ciencia y Tecnología, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
| | - Leandro Matías Sommese
- Departamento de Ciencia y Tecnología, CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
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Wang X, Song J, Yuan Y, Li L, Abu-Taha I, Heijman J, Sun L, Dobrev S, Kamler M, Xie L, Wehrens XH, Horrigan FT, Dobrev D, Li N. Downregulation of FKBP5 Promotes Atrial Arrhythmogenesis. Circ Res 2023; 133:e1-e16. [PMID: 37154033 PMCID: PMC10330339 DOI: 10.1161/circresaha.122.322213] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Accepted: 04/21/2023] [Indexed: 05/10/2023]
Abstract
BACKGROUND Atrial fibrillation (AF), the most common arrhythmia, is associated with the downregulation of FKBP5 (encoding FKBP5 [FK506 binding protein 5]). However, the function of FKBP5 in the heart remains unknown. Here, we elucidate the consequences of cardiomyocyte-restricted loss of FKBP5 on cardiac function and AF development and study the underlying mechanisms. METHODS Right atrial samples from patients with AF were used to assess the protein levels of FKBP5. A cardiomyocyte-specific FKBP5 knockdown mouse model was established by crossbreeding Fkbp5flox/flox mice with Myh6MerCreMer/+ mice. Cardiac function and AF inducibility were assessed by echocardiography and programmed intracardiac stimulation. Histology, optical mapping, cellular electrophysiology, and biochemistry were employed to elucidate the proarrhythmic mechanisms due to loss of cardiomyocyte FKBP5. RESULTS FKBP5 protein levels were lower in the atrial lysates of patients with paroxysmal AF or long-lasting persistent (chronic) AF. Cardiomyocyte-specific knockdown mice exhibited increased AF inducibility and duration compared with control mice. Enhanced AF susceptibility in cardiomyocyte-specific knockdown mice was associated with the development of action potential alternans and spontaneous Ca2+ waves, and increased protein levels and activity of the NCX1 (Na+/Ca2+-exchanger 1), mimicking the cellular phenotype of chronic AF patients. FKBP5-deficiency enhanced transcription of Slc8a1 (encoding NCX1) via transcription factor hypoxia-inducible factor 1α. In vitro studies revealed that FKBP5 negatively modulated the protein levels of hypoxia-inducible factor 1α by competitively interacting with heat-shock protein 90. Injections of the heat-shock protein 90 inhibitor 17-AAG normalized protein levels of hypoxia-inducible factor 1α and NCX1 and reduced AF susceptibility in cardiomyocyte-specific knockdown mice. Furthermore, the atrial cardiomyocyte-selective knockdown of FKBP5 was sufficient to enhance AF arrhythmogenesis. CONCLUSIONS This is the first study to demonstrate a role for the FKBP5-deficiency in atrial arrhythmogenesis and to establish FKBP5 as a negative regulator of hypoxia-inducible factor 1α in cardiomyocytes. Our results identify a potential molecular mechanism for the proarrhythmic NCX1 upregulation in chronic AF patients.
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Affiliation(s)
- Xiaolei Wang
- Department of Medicine (Section of Cardiovascular Research), Baylor College of Medicine, Houston, TX, USA
| | - Jia Song
- Department of Medicine (Section of Cardiovascular Research), Baylor College of Medicine, Houston, TX, USA
| | - Yue Yuan
- Department of Medicine (Section of Cardiovascular Research), Baylor College of Medicine, Houston, TX, USA
| | - Luge Li
- Department of Medicine (Section of Cardiovascular Research), Baylor College of Medicine, Houston, TX, USA
| | - Issam Abu-Taha
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | - Jordi Heijman
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Liang Sun
- Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
| | - Shokoufeh Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | - Markus Kamler
- Department of Thoracic and Cardiovascular Surgery, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | - Liang Xie
- Department of Medicine (Section of Cardiovascular Research), Baylor College of Medicine, Houston, TX, USA
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Xander H.T. Wehrens
- Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Frank T. Horrigan
- Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
- Department of Integrative Physiology, Baylor College of Medicine, Houston, TX, USA
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montréal, Canada
| | - Na Li
- Department of Medicine (Section of Cardiovascular Research), Baylor College of Medicine, Houston, TX, USA
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
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Tóth N, Loewe A, Szlovák J, Kohajda Z, Bitay G, Levijoki J, Papp JG, Varró A, Nagy N. The reverse mode of the Na +/Ca 2+ exchanger contributes to the pacemaker mechanism in rabbit sinus node cells. Sci Rep 2022; 12:21830. [PMID: 36528651 PMCID: PMC9759562 DOI: 10.1038/s41598-022-25574-8] [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: 12/28/2021] [Accepted: 12/01/2022] [Indexed: 12/23/2022] Open
Abstract
Sinus node (SN) pacemaking is based on a coupling between surface membrane ion-channels and intracellular Ca2+-handling. The fundamental role of the inward Na+/Ca2+ exchanger (NCX) is firmly established. However, little is known about the reverse mode exchange. A simulation study attributed important role to reverse NCX activity, however experimental evidence is still missing. Whole-cell and perforated patch-clamp experiments were performed on rabbit SN cells supplemented with fluorescent Ca2+-tracking. We established 2 and 8 mM pipette NaCl groups to suppress and enable reverse NCX. NCX was assessed by specific block with 1 μM ORM-10962. Mechanistic simulations were performed by Maltsev-Lakatta minimal computational SN model. Active reverse NCX resulted in larger Ca2+-transient amplitude with larger SR Ca2+-content. Spontaneous action potential (AP) frequency increased with 8 mM NaCl. When reverse NCX was facilitated by 1 μM strophantin the Ca2+i and spontaneous rate increased. ORM-10962 applied prior to strophantin prevented Ca2+i and AP cycle change. Computational simulations indicated gradually increasing reverse NCX current, Ca2+i and heart rate with increasing Na+i. Our results provide further evidence for the role of reverse NCX in SN pacemaking. The reverse NCX activity may provide additional Ca2+-influx that could increase SR Ca2+-content, which consequently leads to enhanced pacemaking activity.
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Affiliation(s)
- Noémi Tóth
- grid.9008.10000 0001 1016 9625Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, Dóm tér 12, P.O. Box 427, Szeged, 6720 Hungary
| | - Axel Loewe
- grid.7892.40000 0001 0075 5874Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Jozefina Szlovák
- grid.9008.10000 0001 1016 9625Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, Dóm tér 12, P.O. Box 427, Szeged, 6720 Hungary
| | - Zsófia Kohajda
- ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - Gergő Bitay
- grid.9008.10000 0001 1016 9625Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, Dóm tér 12, P.O. Box 427, Szeged, 6720 Hungary
| | - Jouko Levijoki
- grid.419951.10000 0004 0400 1289Orion Pharma, Espoo, Finland
| | - Julius Gy. Papp
- grid.9008.10000 0001 1016 9625Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, Dóm tér 12, P.O. Box 427, Szeged, 6720 Hungary ,ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - András Varró
- grid.9008.10000 0001 1016 9625Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, Dóm tér 12, P.O. Box 427, Szeged, 6720 Hungary ,ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - Norbert Nagy
- grid.9008.10000 0001 1016 9625Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, Dóm tér 12, P.O. Box 427, Szeged, 6720 Hungary ,ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
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5
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Nagy N, Tóth N, Nánási PP. Antiarrhythmic and Inotropic Effects of Selective Na +/Ca 2+ Exchanger Inhibition: What Can We Learn from the Pharmacological Studies? Int J Mol Sci 2022; 23:ijms232314651. [PMID: 36498977 PMCID: PMC9736231 DOI: 10.3390/ijms232314651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 11/25/2022] Open
Abstract
Life-long stable heart function requires a critical balance of intracellular Ca2+. Several ion channels and pumps cooperate in a complex machinery that controls the influx, release, and efflux of Ca2+. Probably one of the most interesting and most complex players of this crosstalk is the Na+/Ca2+ exchanger, which represents the main Ca2+ efflux mechanism; however, under some circumstances, it can also bring Ca2+ into the cell. Therefore, the inhibition of the Na+/Ca2+ exchanger has emerged as one of the most promising possible pharmacological targets to increase Ca2+ levels, to decrease arrhythmogenic depolarizations, and to reduce excessive Ca2+ influx. In line with this, as a response to increasing demand, several more or less selective Na+/Ca2+ exchanger inhibitor compounds have been developed. In the past 20 years, several results have been published regarding the effect of Na+/Ca2+ exchanger inhibition under various circumstances, e.g., species, inhibitor compounds, and experimental conditions; however, the results are often controversial. Does selective Na+/Ca2+ exchanger inhibition have any future in clinical pharmacological practice? In this review, the experimental results of Na+/Ca2+ exchanger inhibition are summarized focusing on the data obtained by novel highly selective inhibitors.
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Affiliation(s)
- Norbert Nagy
- ELKH-SZTE Research Group of Cardiovascular Pharmacology, 6720 Szeged, Hungary
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, 6720 Szeged, Hungary
- Correspondence: ; Tel.: +36-62-545-682; Fax: +36-62-545-680
| | - Noémi Tóth
- ELKH-SZTE Research Group of Cardiovascular Pharmacology, 6720 Szeged, Hungary
| | - Péter P. Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Dental Physiology and Pharmacology, Faculty of Dentistry, University of Debrecen, 4032 Debrecen, Hungary
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6
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Cumberland MJ, Riebel LL, Roy A, O’Shea C, Holmes AP, Denning C, Kirchhof P, Rodriguez B, Gehmlich K. Basic Research Approaches to Evaluate Cardiac Arrhythmia in Heart Failure and Beyond. Front Physiol 2022; 13:806366. [PMID: 35197863 PMCID: PMC8859441 DOI: 10.3389/fphys.2022.806366] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 01/10/2022] [Indexed: 12/20/2022] Open
Abstract
Patients with heart failure often develop cardiac arrhythmias. The mechanisms and interrelations linking heart failure and arrhythmias are not fully understood. Historically, research into arrhythmias has been performed on affected individuals or in vivo (animal) models. The latter however is constrained by interspecies variation, demands to reduce animal experiments and cost. Recent developments in in vitro induced pluripotent stem cell technology and in silico modelling have expanded the number of models available for the evaluation of heart failure and arrhythmia. An agnostic approach, combining the modalities discussed here, has the potential to improve our understanding for appraising the pathology and interactions between heart failure and arrhythmia and can provide robust and validated outcomes in a variety of research settings. This review discusses the state of the art models, methodologies and techniques used in the evaluation of heart failure and arrhythmia and will highlight the benefits of using them in combination. Special consideration is paid to assessing the pivotal role calcium handling has in the development of heart failure and arrhythmia.
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Affiliation(s)
- Max J. Cumberland
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Leto L. Riebel
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Ashwin Roy
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Christopher O’Shea
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Andrew P. Holmes
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Chris Denning
- Stem Cell Biology Unit, Biodiscovery Institute, British Heart Foundation Centre for Regenerative Medicine, University of Nottingham, Nottingham, United Kingdom
| | - Paulus Kirchhof
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- University Heart and Vascular Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Blanca Rodriguez
- Department of Computer Science, University of Oxford, Oxford, United Kingdom
| | - Katja Gehmlich
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford and British Heart Foundation Centre of Research Excellence Oxford, Oxford, United Kingdom
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7
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Hoang-Trong MT, Ullah A, Lederer WJ, Jafri MS. Cardiac Alternans Occurs through the Synergy of Voltage- and Calcium-Dependent Mechanisms. MEMBRANES 2021; 11:794. [PMID: 34677560 PMCID: PMC8539281 DOI: 10.3390/membranes11100794] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/08/2021] [Accepted: 10/12/2021] [Indexed: 11/24/2022]
Abstract
Cardiac alternans is characterized by alternating weak and strong beats of the heart. This signaling at the cellular level may appear as alternating long and short action potentials (APs) that occur in synchrony with alternating large and small calcium transients, respectively. Previous studies have suggested that alternans manifests itself through either a voltage dependent mechanism based upon action potential restitution or as a calcium dependent mechanism based on refractoriness of calcium release. We use a novel model of cardiac excitation-contraction (EC) coupling in the rat ventricular myocyte that includes 20,000 calcium release units (CRU) each with 49 ryanodine receptors (RyR2s) and 7 L-type calcium channels that are all stochastically gated. The model suggests that at the cellular level in the case of alternans produced by rapid pacing, the mechanism requires a synergy of voltage- and calcium-dependent mechanisms. The rapid pacing reduces AP duration and magnitude reducing the number of L-type calcium channels activating individual CRUs during each AP and thus increases the population of CRUs that can be recruited stochastically. Elevated myoplasmic and sarcoplasmic reticulum (SR) calcium, [Ca2+]myo and [Ca2+]SR respectively, increases ryanodine receptor open probability (Po) according to our model used in this simulation and this increased the probability of activating additional CRUs. A CRU that opens in one beat is less likely to open the subsequent beat due to refractoriness caused by incomplete refilling of the junctional sarcoplasmic reticulum (jSR). Furthermore, the model includes estimates of changes in Na+ fluxes and [Na+]i and thus provides insight into how changes in electrical activity, [Na+]i and sodium-calcium exchanger activity can modulate alternans. The model thus tracks critical elements that can account for rate-dependent changes in [Na+]i and [Ca2+]myo and how they contribute to the generation of Ca2+ signaling alternans in the heart.
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Affiliation(s)
- Minh Tuan Hoang-Trong
- Krasnow Institute for Advanced Study and School of Systems Biology, George Mason University, Fairfax, VA 22030, USA; (M.T.H.-T.); (A.U.)
| | - Aman Ullah
- Krasnow Institute for Advanced Study and School of Systems Biology, George Mason University, Fairfax, VA 22030, USA; (M.T.H.-T.); (A.U.)
| | - William Jonathan Lederer
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA;
| | - Mohsin Saleet Jafri
- Krasnow Institute for Advanced Study and School of Systems Biology, George Mason University, Fairfax, VA 22030, USA; (M.T.H.-T.); (A.U.)
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA;
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8
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Tóth N, Szlovák J, Kohajda Z, Bitay G, Veress R, Horváth B, Papp JG, Varró A, Nagy N. The development of L-type Ca 2+ current mediated alternans does not depend on the restitution slope in canine ventricular myocardium. Sci Rep 2021; 11:16652. [PMID: 34404848 PMCID: PMC8371021 DOI: 10.1038/s41598-021-95299-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 07/23/2021] [Indexed: 11/25/2022] Open
Abstract
Cardiac alternans have crucial importance in the onset of ventricular fibrillation. The early explanation for alternans development was the voltage-driven mechanism, where the action potential (AP) restitution steepness was considered as crucial determining factor. Recent results suggest that restitution slope is an inadequate predictor for alternans development, but several studies still claim the role of membrane potential as underlying mechanism of alternans. These controversial data indicate that the relationship of restitution and alternans development is not completely understood. APs were measured by conventional microelectrode technique from canine right ventricular papillary muscles. Ionic currents combined with fluorescent measurements were recorded by patch-clamp technique. APs combined with fluorescent measurements were monitored by sharp microelectrodes. Rapid pacing evoked restitution-independent AP duration (APD) alternans. When non-alternating AP voltage command was used, Ca2+i-transient (CaT) alternans were not observed. When alternating rectangular voltage pulses were applied, CaT alternans were proportional to ICaL amplitude alternans. Selective ICaL inhibition did not influence the fast phase of APD restitution. In this study we found that ICaL has minor contribution in shaping the fast phase of restitution curve suggesting that ICaL—if it plays important role in the alternans mechanism—could be an additional factor that attenuates the reliability of APD restitution slope to predict alternans.
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Affiliation(s)
- Noémi Tóth
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, P.O. Box 427, 6720, Szeged, Hungary
| | - Jozefina Szlovák
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, P.O. Box 427, 6720, Szeged, Hungary
| | - Zsófia Kohajda
- ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - Gergő Bitay
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, P.O. Box 427, 6720, Szeged, Hungary
| | - Roland Veress
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Faculty of Pharmacy, University of Debrecen, Debrecen, Hungary
| | - Julius Gy Papp
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, P.O. Box 427, 6720, Szeged, Hungary.,ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, P.O. Box 427, 6720, Szeged, Hungary.,ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary.,Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary
| | - Norbert Nagy
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Dóm tér 12, P.O. Box 427, 6720, Szeged, Hungary. .,ELKH-SZTE Research Group of Cardiovascular Pharmacology, Szeged, Hungary.
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