1
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Yfanti C, Vestbjerg B, Van't Westende J, Edvardsson N, Monfort LM, Olesen MS, Bentzen BH, Grunnet M, Eveleens Maarse BC, Diness JG, Kemme MJB, Sørensen U, Moerland M, van Esdonk MJ, Klaassen ES, Gal P, Holst AG. A phase 1 trial of AP30663, a K Ca2 channel inhibitor in development for conversion of atrial fibrillation. Br J Clin Pharmacol 2024; 90:1027-1035. [PMID: 37990600 DOI: 10.1111/bcp.15973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 09/19/2023] [Accepted: 10/11/2023] [Indexed: 11/23/2023] Open
Abstract
AIMS AP30663 is a novel compound under development for pharmacological conversion of atrial fibrillation by targeting the small conductance Ca2+ activated K+ (KCa2) channel. The aim of this extension phase 1 study was to test AP30663 at higher single doses compared to the first-in-human trial. METHODS Sixteen healthy male volunteers were randomized into 2 cohorts: 6- and 8-mg/kg intravenous single-dose administration of AP30663 vs. placebo. Safety, pharmacokinetic and pharmacodynamic data were collected. RESULTS AP30663 was associated with mild and transient infusion site reactions with no clustering of other adverse events but with an estimated maximum mean QTcF interval prolongation of 45.2 ms (95% confidence interval 31.5-58.9) in the 6 mg/kg dose level and 50.4 ms (95% confidence interval 36.7-64.0) with 8 mg/kg. Pharmacokinetics was dose proportional with terminal half-life of around 3 h. CONCLUSION AP30663 in doses up to 8 mg/kg was associated with mild and transient infusion site reactions and an increase of the QTcF interval. Supporting Information support that the QTc effect may be explained by an off-target inhibition of the IKr channel.
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Affiliation(s)
| | | | | | - Nils Edvardsson
- Acesion Pharma ApS, Copenhagen, Denmark
- Department of Molecular and Clinical Medicine/Cardiology, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | | | | | - Bo Hjorth Bentzen
- Acesion Pharma ApS, Copenhagen, Denmark
- Department of Biomedical Sciences, University of Copenhagen, Denmark
| | | | - Boukje C Eveleens Maarse
- Centre for Human Drug Research, Leiden, the Netherlands
- Leiden University Medical Centre, Leiden, the Netherlands
| | | | | | | | - Matthijs Moerland
- Centre for Human Drug Research, Leiden, the Netherlands
- Leiden University Medical Centre, Leiden, the Netherlands
| | | | | | - Pim Gal
- Centre for Human Drug Research, Leiden, the Netherlands
- Leiden University Medical Centre, Leiden, the Netherlands
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2
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Ewart G, Bobardt M, Bentzen BH, Yan Y, Thomson A, Klumpp K, Becker S, Rosenkilde MM, Miller M, Gallay P. Post-infection treatment with the E protein inhibitor BIT225 reduces disease severity and increases survival of K18-hACE2 transgenic mice infected with a lethal dose of SARS-CoV-2. PLoS Pathog 2023; 19:e1011328. [PMID: 37549173 PMCID: PMC10434922 DOI: 10.1371/journal.ppat.1011328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 08/17/2023] [Accepted: 07/06/2023] [Indexed: 08/09/2023] Open
Abstract
The Coronavirus envelope (E) protein is a small structural protein with ion channel activity that plays an important role in virus assembly, budding, immunopathogenesis and disease severity. The viroporin E is also located in Golgi and ER membranes of infected cells and is associated with inflammasome activation and immune dysregulation. Here we evaluated in vitro antiviral activity, mechanism of action and in vivo efficacy of BIT225 for the treatment of SARS-CoV-2 infection. BIT225 showed broad-spectrum direct-acting antiviral activity against SARS-CoV-2 in Calu3 and Vero cells with similar potency across 6 different virus strains. BIT225 inhibited ion channel activity of E protein but did not inhibit endogenous currents or calcium-induced ion channel activity of TMEM16A in Xenopus oocytes. BIT225 administered by oral gavage for 12 days starting 12 hours before infection completely prevented body weight loss and mortality in SARS-CoV-2 infected K18 mice (100% survival, n = 12), while all vehicle-dosed animals reached a mortality endpoint by Day 9 across two studies (n = 12). When treatment started at 24 hours after infection, body weight loss, and mortality were also prevented (100% survival, n = 5), while 4 of 5 mice maintained and increased body weight and survived when treatment started 48 hours after infection. Treatment efficacy was dependent on BIT225 dose and was associated with significant reductions in lung viral load (3.5 log10), virus titer (4000 pfu/ml) and lung and serum cytokine levels. These results validate viroporin E as a viable antiviral target and support the clinical study of BIT225 for treatment and prophylaxis of SARS-CoV-2 infection.
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Affiliation(s)
- Gary Ewart
- Biotron Limited, North Ryde, New South Wales, Australia
| | - Michael Bobardt
- The Scripps Institute, Immunology and Microbiology, La Jolla, California, United States of America
| | - Bo Hjorth Bentzen
- University of Copenhagen, Department of Biomedical Sciences, Copenhagen, Denmark
| | - Yannan Yan
- University of Copenhagen, Department of Biomedical Sciences, Copenhagen, Denmark
| | | | - Klaus Klumpp
- Biotron Limited, North Ryde, New South Wales, Australia
| | | | - Mette M. Rosenkilde
- University of Copenhagen, Department of Biomedical Sciences, Copenhagen, Denmark
| | | | - Philippe Gallay
- The Scripps Institute, Immunology and Microbiology, La Jolla, California, United States of America
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3
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Hiniesto-Iñigo I, Castro-Gonzalez LM, Corradi V, Skarsfeldt MA, Yazdi S, Lundholm S, Nikesjö J, Noskov SY, Bentzen BH, Tieleman DP, Liin SI. Endocannabinoids enhance hK V7.1/KCNE1 channel function and shorten the cardiac action potential and QT interval. EBioMedicine 2023; 89:104459. [PMID: 36796231 PMCID: PMC9958262 DOI: 10.1016/j.ebiom.2023.104459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 01/11/2023] [Accepted: 01/18/2023] [Indexed: 02/15/2023] Open
Abstract
BACKGROUND Genotype-positive patients who suffer from the cardiac channelopathy Long QT Syndrome (LQTS) may display a spectrum of clinical phenotypes, with often unknown causes. Therefore, there is a need to identify factors influencing disease severity to move towards an individualized clinical management of LQTS. One possible factor influencing the disease phenotype is the endocannabinoid system, which has emerged as a modulator of cardiovascular function. In this study, we aim to elucidate whether endocannabinoids target the cardiac voltage-gated potassium channel KV7.1/KCNE1, which is the most frequently mutated ion channel in LQTS. METHODS We used two-electrode voltage clamp, molecular dynamics simulations and the E4031 drug-induced LQT2 model of ex-vivo guinea pig hearts. FINDINGS We found a set of endocannabinoids that facilitate channel activation, seen as a shifted voltage-dependence of channel opening and increased overall current amplitude and conductance. We propose that negatively charged endocannabinoids interact with known lipid binding sites at positively charged amino acids on the channel, providing structural insights into why only specific endocannabinoids modulate KV7.1/KCNE1. Using the endocannabinoid ARA-S as a prototype, we show that the effect is not dependent on the KCNE1 subunit or the phosphorylation state of the channel. In guinea pig hearts, ARA-S was found to reverse the E4031-prolonged action potential duration and QT interval. INTERPRETATION We consider the endocannabinoids as an interesting class of hKV7.1/KCNE1 channel modulators with putative protective effects in LQTS contexts. FUNDING ERC (No. 850622), Canadian Institutes of Health Research, Canada Research Chairs and Compute Canada, Swedish National Infrastructure for Computing.
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Affiliation(s)
- Irene Hiniesto-Iñigo
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Laura M Castro-Gonzalez
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Valentina Corradi
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Mark A Skarsfeldt
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Samira Yazdi
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Siri Lundholm
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Johan Nikesjö
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Sergei Yu Noskov
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Bo Hjorth Bentzen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - D Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden.
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4
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Godoy-Marín H, Jiménez-Sábado V, Tarifa C, Ginel A, Santos JLD, Bentzen BH, Hove-Madsen L, Ciruela F. Increased Density of Endogenous Adenosine A 2A Receptors in Atrial Fibrillation: From Cellular and Porcine Models to Human Patients. Int J Mol Sci 2023; 24:ijms24043668. [PMID: 36835078 PMCID: PMC9963500 DOI: 10.3390/ijms24043668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 02/04/2023] [Accepted: 02/09/2023] [Indexed: 02/17/2023] Open
Abstract
Adenosine, an endogenous nucleoside, plays a critical role in maintaining homeostasis during stressful situations, such as energy deprivation or cellular damage. Therefore, extracellular adenosine is generated locally in tissues under conditions such as hypoxia, ischemia, or inflammation. In fact, plasma levels of adenosine in patients with atrial fibrillation (AF) are elevated, which also correlates with an increased density of adenosine A2A receptors (A2ARs) both in the right atrium and in peripheral blood mononuclear cells (PBMCs). The complexity of adenosine-mediated effects in health and disease requires simple and reproducible experimental models of AF. Here, we generate two AF models, namely the cardiomyocyte cell line HL-1 submitted to Anemonia toxin II (ATX-II) and a large animal model of AF, the right atrium tachypaced pig (A-TP). We evaluated the density of endogenous A2AR in those AF models. Treatment of HL-1 cells with ATX-II reduced cell viability, while the density of A2AR increased significantly, as previously observed in cardiomyocytes with AF. Next, we generated the animal model of AF based on tachypacing pigs. In particular, the density of the key calcium regulatory protein calsequestrin-2 was reduced in A-TP animals, which is consistent with the atrial remodelling shown in humans suffering from AF. Likewise, the density of A2AR in the atrium of the AF pig model increased significantly, as also shown in the biopsies of the right atrium of subjects with AF. Overall, our findings revealed that these two experimental models of AF mimicked the alterations in A2AR density observed in patients with AF, making them attractive models for studying the adenosinergic system in AF.
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Affiliation(s)
- Héctor Godoy-Marín
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, 08907 L’Hospitalet de Llobregat, Spain
- Neuropharmacology & Pain Group, Neuroscience Program, Bellvitge Institute for Biomedical Research, 08907 L’Hospitalet de Llobregat, Spain
| | - Verónica Jiménez-Sábado
- Biomedical Research Institute Sant Pau, IIB Sant Pau, 08025 Barcelona, Spain
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, 28029 Madrid, Spain
| | - Carmen Tarifa
- Biomedical Research Institute Sant Pau, IIB Sant Pau, 08025 Barcelona, Spain
- Biomedical Research Institute of Barcelona, IIBB-CSIC, 08036 Barcelona, Spain
| | - Antonino Ginel
- Department Cardiac Surgery, Hospital de la Santa Creu i Sant Pau, 08036 Barcelona, Spain
| | | | - Bo Hjorth Bentzen
- Department of Biomedical Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Leif Hove-Madsen
- Biomedical Research Institute Sant Pau, IIB Sant Pau, 08025 Barcelona, Spain
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, 28029 Madrid, Spain
- Biomedical Research Institute of Barcelona, IIBB-CSIC, 08036 Barcelona, Spain
- Correspondence: (L.H.-M.); (F.C.)
| | - Francisco Ciruela
- Pharmacology Unit, Department of Pathology and Experimental Therapeutics, School of Medicine and Health Sciences, Institute of Neurosciences, University of Barcelona, 08907 L’Hospitalet de Llobregat, Spain
- Neuropharmacology & Pain Group, Neuroscience Program, Bellvitge Institute for Biomedical Research, 08907 L’Hospitalet de Llobregat, Spain
- Correspondence: (L.H.-M.); (F.C.)
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5
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Toft-Bertelsen TL, Jeppesen MG, Landbrug A, Mujezinovic A, Bentzen BH, Kledal TN, Rosenkilde MM. Reply to: How Many SARS-CoV-2 "Viroporins" Are Really Ion Channels? Commun Biol 2022; 5:860. [PMID: 36008476 PMCID: PMC9411598 DOI: 10.1038/s42003-022-03670-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Accepted: 07/01/2022] [Indexed: 11/21/2022] Open
Affiliation(s)
- Trine L Toft-Bertelsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mads Gravers Jeppesen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Synklino ApS, Charlottenlund, Denmark
| | - Asante Landbrug
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Amer Mujezinovic
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bo Hjorth Bentzen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Mette Marie Rosenkilde
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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6
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Linz B, Hesselkilde EM, Skarsfeldt MA, Hertel JN, Sattler SM, Yan Y, Tfelt-Hansen J, Diness JG, Bentzen BH, Linz D, Jespersen T. Pharmacological inhibition of SK-channels with AP14145 prevents atrial arrhythmogenic changes in a porcine model for obstructive respiratory events. Europace 2022. [DOI: 10.1093/europace/euac053.616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
Funding Acknowledgements
Type of funding sources: Foundation. Main funding source(s): This work was supported by the Novo Nordisk Foundation (Tandem Programme; #31634).
Background
Obstructive sleep apnea (OSA) creates a complex substrate for atrial fibrillation (AF), which is refractory to many clinically available pharmacological interventions.
Purpose
To investigate atrial antiarrhythmogenic properties and ventricular electrophysiological safety of small-conductance Ca2+ -activated K+ (SK)- channel inhibition in a porcine model for obstructive respiratory events.
Methods
In spontaneously breathing pigs, obstructive respiratory events were simulated by intermittent negative upper airway pressure (INAP) applied via a pressure device connected to the intubation tube. INAP was applied for 75 seconds, every 10 minutes, three times before and three times during infusion of the SK-channel inhibitor AP14145. Atrial effective refractory periods (AERP) were acquired before (Pre-INAP), during (INAP) and after (Post-) INAP. AF-inducibility was determined by a S1S2 atrial pacing protocol. For the purpose of drug safety, ventricular arrhythmicity was evaluated by heart rate adjusted QT-interval duration (QT-paced) and electromechanical window (EMW) calculation.
Results
During vehicle infusion, INAP transiently shortened AERP (Pre-INAP: 135±10 ms vs. Post-INAP 101±11 ms; p=0.008) and increased AF-inducibility. QT-paced prolonged during INAP (Pre-INAP 270±7 ms vs. INAP 275±7 ms; p=0.04) and EMW shortened progressively throughout INAP and Post-INAP (Pre-INAP 80±4 ms; INAP 59±6 ms, Post-INAP 46±10 ms). AP14145 prolonged baseline AERP, partially prevented INAP-induced AERP-shortening and reduced AF-susceptibility. AP14145 did neither alter QT-paced (Pre-AP14145 270±7 ms vs. AP14145 268±6 ms, p=0.83) nor INAP-induced QT-paced prolongation, but blunted Post-INAP associated EMW-shortening.
Conclusion
In a pig model for obstructive respiratory events, the SK-channel-inhibitor AP14145 prevented INAP-associated AERP-shortening and AF-susceptibility without impairing ventricular electrophysiology. Hence, SK-channels may represent a promising target for OSA-related AF.
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Affiliation(s)
- B Linz
- University of Copenhagen, Faculty of Health and Medical Sciences, Department of Biomedical Sciences, Copenhagen, Denmark
| | - EM Hesselkilde
- University of Copenhagen, Faculty of Health and Medical Sciences, Department of Biomedical Sciences, Copenhagen, Denmark
| | - MA Skarsfeldt
- University of Copenhagen, Faculty of Health and Medical Sciences, Department of Biomedical Sciences, Copenhagen, Denmark
| | - JN Hertel
- University of Copenhagen, Faculty of Health and Medical Sciences, Department of Biomedical Sciences, Copenhagen, Denmark
| | - SM Sattler
- University of Copenhagen, Faculty of Health and Medical Sciences, Department of Biomedical Sciences, Copenhagen, Denmark
| | - Y Yan
- University of Copenhagen, Faculty of Health and Medical Sciences, Department of Biomedical Sciences, Copenhagen, Denmark
| | - J Tfelt-Hansen
- Rigshospitalet - Copenhagen University Hospital, Department of Cardiology, Copenhagen, Denmark
| | | | - BH Bentzen
- University of Copenhagen, Faculty of Health and Medical Sciences, Department of Biomedical Sciences, Copenhagen, Denmark
| | - D Linz
- Cardiovascular Research Institute Maastricht (CARIM), Maastricht, Netherlands (The)
| | - T Jespersen
- University of Copenhagen, Faculty of Health and Medical Sciences, Department of Biomedical Sciences, Copenhagen, Denmark
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7
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Vad OB, Yan Y, Denti F, Ahlberg G, Refsgaard L, Bomholtz SH, Santos JL, Rasmussen S, Haunsø S, Svendsen JH, Christophersen IE, Schmitt N, Olesen MS, Bentzen BH. Whole-Exome Sequencing Implicates Neuronal Calcium Channel with Familial Atrial Fibrillation. Front Genet 2022; 13:806429. [PMID: 35154276 PMCID: PMC8832975 DOI: 10.3389/fgene.2022.806429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 01/03/2022] [Indexed: 11/13/2022] Open
Abstract
Background: Atrial Fibrillation (AF) is the most prevalent sustained cardiac arrhythmia, responsible for considerable morbidity and mortality. The heterogenic and complex pathogenesis of AF remains poorly understood, which contributes to the current limitation in effective treatments. We aimed to identify rare genetic variants associated with AF in patients with familial AF. Methods and results: We performed whole exome sequencing in a large family with familial AF and identified a rare variant in the gene CACNA1A c.5053G > A which co-segregated with AF. The gene encodes for the protein variants CaV2.1-V1686M, and is important in neuronal function. Functional characterization of the CACNA1A, using patch-clamp recordings on transiently transfected mammalian cells, revealed a modest loss-of-function of CaV2.1-V1686M. Conclusion: We identified a rare loss-of-function variant associated with AF in a gene previously linked with neuronal function. The results allude to a novel link between dysfunction of an ion channel previously associated with neuronal functions and increased risk of developing AF.
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Affiliation(s)
- Oliver Bundgaard Vad
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Laboratory for Molecular Cardiology, Department of Cardiology, Centre for Cardiac, Vascular-, Pulmonary and Infectious Diseases, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Yannan Yan
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Federico Denti
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gustav Ahlberg
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Laboratory for Molecular Cardiology, Department of Cardiology, Centre for Cardiac, Vascular-, Pulmonary and Infectious Diseases, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Lena Refsgaard
- Laboratory for Molecular Cardiology, Department of Cardiology, Centre for Cardiac, Vascular-, Pulmonary and Infectious Diseases, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Sofia Hammami Bomholtz
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Joana Larupa Santos
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Simon Rasmussen
- Disease Systems Biology Program, University of Copenhagen, Copenhagen, Denmark
| | - Stig Haunsø
- Laboratory for Molecular Cardiology, Department of Cardiology, Centre for Cardiac, Vascular-, Pulmonary and Infectious Diseases, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Jesper Hastrup Svendsen
- Laboratory for Molecular Cardiology, Department of Cardiology, Centre for Cardiac, Vascular-, Pulmonary and Infectious Diseases, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ingrid Elizabeth Christophersen
- The Department of Medical Genetics, Oslo University Hospital, Oslo, Norway
- Department of Medical Research, Bærum Hospital, Vestre Viken Hospital Trust, Rud, Norway
| | - Nicole Schmitt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Morten Salling Olesen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Laboratory for Molecular Cardiology, Department of Cardiology, Centre for Cardiac, Vascular-, Pulmonary and Infectious Diseases, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
- *Correspondence: Morten Salling Olesen,
| | - Bo Hjorth Bentzen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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8
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Gatta G, Sobota V, Citerni C, Diness JG, Sørensen US, Jespersen T, Bentzen BH, Zeemering S, Kuiper M, Verheule S, Schotten U, van Hunnik A. Effective termination of atrial fibrillation by SK channel inhibition is associated with a sudden organization of fibrillatory conduction. Europace 2021; 23:1847-1859. [PMID: 34080619 PMCID: PMC8576281 DOI: 10.1093/europace/euab125] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 04/22/2021] [Indexed: 11/12/2022] Open
Abstract
AIMS Pharmacological termination of atrial fibrillation (AF) remains a challenge due to limited efficacy and potential ventricular proarrhythmic effects of antiarrhythmic drugs. SK channels are proposed as atrial-specific targets in the treatment of AF. Here, we investigated the effects of the new SK channel inhibitor AP14145. METHODS AND RESULTS Eight goats were implanted with pericardial electrodes for induction of AF (30 days). In an open-chest study, the atrial conduction velocity (CV) and effective refractory period (ERP) were measured during pacing. High-density mapping of both atrial free-walls was performed during AF and conduction properties were assessed. All measurements were performed at baseline and during AP14145 infusion [10 mg/kg/h (n = 1) or 20 mg/kg/h (n = 6)]. At an infusion rate of 20 mg/kg/h, AF terminated in five of six goats. AP14145 profoundly increased ERP and reduced CV during pacing. AP14145 increased spatiotemporal instability of conduction at short pacing cycle lengths. Atrial fibrillation cycle length and pathlength (AF cycle length × CV) underwent a strong dose-dependent prolongation. Conduction velocity during AF remained unchanged and conduction patterns remained complex until the last seconds before AF termination, during which a sudden and profound organization of fibrillatory conduction occurred. CONCLUSION AP14145 provided a successful therapy for termination of persistent AF in goats. During AF, AP14145 caused an ERP and AF cycle length prolongation. AP14145 slowed CV during fast pacing but did not lead to a further decrease during AF. Termination of AF was preceded by an abrupt organization of AF with a decline in the number of fibrillation waves.
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Affiliation(s)
- Giulia Gatta
- Department of Physiology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
| | - Vladimir Sobota
- Department of Physiology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
| | - Carlotta Citerni
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | | | - Thomas Jespersen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bo Hjorth Bentzen
- Acesion Pharma, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Stef Zeemering
- Department of Physiology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
| | - Marion Kuiper
- Department of Physiology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
| | - Sander Verheule
- Department of Physiology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
| | - Ulrich Schotten
- Department of Physiology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
| | - Arne van Hunnik
- Department of Physiology, Maastricht University, P.O. Box 616, 6200 MD Maastricht, The Netherlands
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9
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Grupe M, Bentzen BH, Benned-Jensen T, Nielsen V, Frederiksen K, Jensen HS, Jacobsen AM, Skibsbye L, Sams AG, Grunnet M, Rottländer M, Bastlund JF. In vitro and in vivo characterization of Lu AA41178: A novel, brain penetrant, pan-selective Kv7 potassium channel opener with efficacy in preclinical models of epileptic seizures and psychiatric disorders. Eur J Pharmacol 2020; 887:173440. [PMID: 32745603 DOI: 10.1016/j.ejphar.2020.173440] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/28/2020] [Accepted: 07/29/2020] [Indexed: 12/29/2022]
Abstract
Activation of the voltage-gated Kv7 channels holds therapeutic promise in several neurological and psychiatric disorders, including epilepsy, schizophrenia, and depression. Here, we present a pharmacological characterization of Lu AA41178, a novel, pan-selective Kv7.2-7.5 opener, using both in vitro assays and a broad range of in vivo assays with relevance to epilepsy, schizophrenia, and depression. Electrophysiological characterization in Xenopus oocytes expressing human Kv7.2-Kv7.5 confirmed Lu AA41178 as a pan-selective opener of Kv7 channels by significantly left-shifting the activation threshold. Additionally, Lu AA41178 was tested in vitro for off-target effects, demonstrating a clean Kv7-selective profile, with no impact on common cardiac ion channels, and no potentiating activity on GABAA channels. Lu AA41178 was evaluated across preclinical in vivo assays with relevance to neurological and psychiatric disorders. In the maximum electroshock seizure threshold test and PTZ seizure threshold test, Lu AA41178 significantly increased the seizure thresholds in mice, demonstrating anticonvulsant efficacy. Lu AA41178 demonstrated antipsychotic-like activity by reducing amphetamine-induced hyperlocomotion in mice as well as lowering conditioned avoidance responses in rats. In the mouse forced swim test, a model with antidepressant predictivity, Lu AA41178 significantly reduced immobility. Additionally, behavioral effects typically observed with Kv7 openers was also characterized. In vivo assays were accompanied by plasma and brain exposures, revealing minimum effective plasma levels <1000 ng/ml. Lu AA41178, a potent opener of neuronal Kv7 channels demonstrate efficacy in assays of epilepsy, schizophrenia and depression and might serve as a valuable tool for exploring the role of Kv7 channels in both neurological and psychiatric disorders.
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Affiliation(s)
- Morten Grupe
- H. Lundbeck A/S, Ottiliavej 9, 2500 Valby, Denmark.
| | - Bo Hjorth Bentzen
- Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark
| | | | | | | | | | | | | | | | | | - Mario Rottländer
- CMC Outsourcing, Novo Nordisk A/S, Smoermosevej 17-19, 2880 Bagsvaerd, Denmark
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10
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Soattin L, Lubberding AF, Bentzen BH, Christ T, Jespersen T. Inhibition of Adenosine Pathway Alters Atrial Electrophysiology and Prevents Atrial Fibrillation. Front Physiol 2020; 11:493. [PMID: 32595514 PMCID: PMC7304385 DOI: 10.3389/fphys.2020.00493] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 04/23/2020] [Indexed: 01/13/2023] Open
Abstract
Background Adenosine leads to atrial action potential (AP) shortening through activation of adenosine 1 receptors (A1-R) and subsequent opening of G-protein-coupled inwardly rectifying K+ channels. Extracellular production of adenosine is drastically increased during stress and ischemia. Objective The aim of this study was to address whether the pharmacological blockade of endogenous production of adenosine and of its signaling prevents atrial fibrillation (AF). Methods The role of A1-R activation on atrial action potential duration, refractoriness, and AF vulnerability was investigated in rat isolated beating heart preparations (Langendorff) with an A1-R agonist [2-chloro-N6-cyclopentyladenosine (CCPA), 50 nM] and antagonist [1-butyl-3-(3-hydroxypropyl)-8-(3-noradamantyl)xanthine (PSB36), 40 nM]. Furthermore, to interfere with the endogenous adenosine release, the ecto-5′-nucleotidase (CD73) inhibitor was applied [5′-(α,β-methylene) diphosphate sodium salt (AMPCP), 500 μM]. Isolated trabeculae from human right atrial appendages (hRAAs) were used for comparison. Results As expected, CCPA shortened AP duration at 90% of repolarization (APD90) and effective refractory period (ERP) in rat atria. PSB36 prolonged APD90 and ERP in rat atria, and CD73 inhibition with AMPCP prolonged ERP in rats, confirming that endogenously produced amount of adenosine is sufficiently high to alter atrial electrophysiology. In human atrial appendages, CCPA shortened APD90, while PSB36 prolonged it. Rat hearts treated with CCPA are prone to AF. In contrast, PSB36 and AMPCP prevented AF events and reduced AF duration (vehicle, 11.5 ± 2.6 s; CCPA, 40.6 ± 16.1 s; PSB36, 6.5 ± 3.7 s; AMPCP, 3.0 ± 1.4 s; P < 0.0001). Conclusion A1-R activation by intrinsic adenosine release alters atrial electrophysiology and promotes AF. Inhibition of adenosine pathway protects atria from arrhythmic events.
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Affiliation(s)
- Luca Soattin
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Anniek Frederike Lubberding
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bo Hjorth Bentzen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Torsten Christ
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Hamburg, Germany
| | - Thomas Jespersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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11
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Diness JG, Abildgaard L, Bomholtz SH, Skarsfeldt MA, Edvardsson N, Sørensen US, Grunnet M, Bentzen BH. Inhibition of K Ca2 Channels Decreased the Risk of Ventricular Arrhythmia in the Guinea Pig Heart During Induced Hypokalemia. Front Pharmacol 2020; 11:749. [PMID: 32508659 PMCID: PMC7251152 DOI: 10.3389/fphar.2020.00749] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 05/06/2020] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Hypokalemia reduces the cardiac repolarization reserve. This prolongs the QT-interval and increases the risk of ventricular arrhythmia; a risk that is exacerbated by administration of classical class 3 anti-arrhythmic agents.Small conductance Ca2+-activated K+-channels (KCa2) are a promising new atrial selective target for treatment of atrial fibrillation. Under physiological conditions KCa2 plays a minor role in ventricular repolarization. However, this might change under hypokalemia because of concomitant increases in ventriculay -60r intracellur Ca2+. PURPOSE To study the effects of pharmacological KCa2 channel inhibition by the compounds AP14145, ICA, or AP30663 under hypokalemic conditions as compared to dofetilide and hypokalemia alone time-matched controls (TMC). METHODS The current at +10 mV was compared in HEK293 cells stably expressing KCa2.3 perfused first with normo- and then hypokalemic solutions (4 mM K+ and 2.5 mM K+, respectively). Guinea pig hearts were isolated and perfused with normokalemic (4 mM K+) Krebs-Henseleit solution, followed by perfusion with drug or vehicle control. The perfusion was then changed to hypokalemic solution (2.5 mM K+) in presence of drug. 30 animals were randomly assigned to 5 groups: ICA, AP14145, AP30663, dofetilide, or TMC. QT-interval, the interval from the peak to the end of the T wave (Tp-Te), ventricular effective refractory period (VERP), arrhythmia score, and ventricular fibrillation (VF) incidence were recorded. RESULTS Hypokalemia slightly increased KCa2.3 current compared to normokalemia. Application of KCa2 channel inhibitors and dofetilide prolonged the QT interval corrected for heart rate. Dofetilide, but none of the KCa2 channel inhibitors increased Tp-Te during hypokalemia. During hypokalemia 4/6 hearts in the TMC group developed VF (two spontaneously, two by S1S2 stimulation) whereas 5/6 hearts developed VF in the dofetilide group (two spontaneously, three by S1S2 stimulation). In comparison, 0/6, 1/6, and 1/6 hearts developed VF when treated with the KCa2 channel inhibitors AP30663, ICA, or AP14145, respectively. CONCLUSION Hypokalemia was associated with an increased incidence of VF, an effect that also seen in the presence of dofetilide. In comparison, the structurally and functionally different KCa2 channel inhibitors, ICA, AP14145, and AP30663 protected the heart from hypokalemia induced VF. These results support that KCa2 inhibition may be associated with a better safety and tolerability profile than dofetilide.
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Affiliation(s)
| | | | - Sofia Hammami Bomholtz
- Acesion Pharma, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mark Alexander Skarsfeldt
- Acesion Pharma, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nils Edvardsson
- Acesion Pharma, Copenhagen, Denmark
- Department of Molecular and Clinical Medicine/Cardiology, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | | | | | - Bo Hjorth Bentzen
- Acesion Pharma, Copenhagen, Denmark
- Department of Molecular and Clinical Medicine/Cardiology, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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12
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Larupa Santos J, Rodríguez I, S. Olesen M, Hjorth Bentzen B, Schmitt N. Investigating gene-microRNA networks in atrial fibrillation patients with mitral valve regurgitation. PLoS One 2020; 15:e0232719. [PMID: 32392228 PMCID: PMC7213724 DOI: 10.1371/journal.pone.0232719] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 04/20/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Atrial fibrillation (AF) is predicted to affect around 17.9 million individuals in Europe by 2060. The disease is associated with severe electrical and structural remodelling of the heart, and increased the risk of stroke and heart failure. In order to improve treatment and find new drug targets, the field needs to better comprehend the exact molecular mechanisms in these remodelling processes. OBJECTIVES This study aims to identify gene and miRNA networks involved in the remodelling of AF hearts in AF patients with mitral valve regurgitation (MVR). METHODS Total RNA was extracted from right atrial biopsies from patients undergoing surgery for mitral valve replacement or repair with AF and without history of AF to test for differentially expressed genes and miRNAs using RNA-sequencing and miRNA microarray. In silico predictions were used to construct a mRNA-miRNA network including differentially expressed mRNAs and miRNAs. Gene and chromosome enrichment analysis were used to identify molecular pathways and high-density AF loci. RESULTS We found 644 genes and 43 miRNAs differentially expressed in AF patients compared to controls. From these lists, we identified 905 pairs of putative miRNA-mRNA interactions, including 37 miRNAs and 295 genes. Of particular note, AF-associated miR-130b-3p, miR-338-5p and miR-208a-3p were differentially expressed in our AF tissue samples. These miRNAs are predicted regulators of several differentially expressed genes associated with cardiac conduction and fibrosis. We identified two high-density AF loci in chromosomes 14q11.2 and 6p21.3. CONCLUSIONS AF in MVR patients is associated with down-regulation of ion channel genes and up-regulation of extracellular matrix genes. Other AF related genes are dysregulated and several are predicted to be targeted by miRNAs. Our novel miRNA-mRNA regulatory network provides new insights into the mechanisms of AF.
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Affiliation(s)
- Joana Larupa Santos
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Ismael Rodríguez
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Morten S. Olesen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen N, Denmark
- Department of Cardiology, Laboratory for Molecular Cardiology, The Heart Centre, Rigshospitalet, University Hospital of Copenhagen, Copenhagen Ø, Denmark
| | - Bo Hjorth Bentzen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen N, Denmark
| | - Nicole Schmitt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen N, Denmark
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13
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Bentzen BH, Bomholtz SH, Simó-Vicens R, Folkersen L, Abildgaard L, Speerschneider T, Muthukumarasamy KM, Edvardsson N, Sørensen US, Grunnet M, Diness JG. Mechanisms of Action of the KCa2-Negative Modulator AP30663, a Novel Compound in Development for Treatment of Atrial Fibrillation in Man. Front Pharmacol 2020; 11:610. [PMID: 32477117 PMCID: PMC7232560 DOI: 10.3389/fphar.2020.00610] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 04/20/2020] [Indexed: 12/17/2022] Open
Abstract
Aims Small conductance Ca2+-activated K+ channels (SK channels, KCa2) are a new target for treatment of atrial fibrillation (AF). AP30663 is a small molecule inhibitor of KCa2 channels that is currently in clinical development for treatment of AF. The aim of this study is to present the electrophysiological profile and mechanism of action of AP30663 and its efficacy in prolonging atrial refractoriness in rodents, and by bioinformatic analysis investigate if genetic variants in KCNN2 or KCNN3 influence the expression level of these in human heart tissue. Methods and Results Whole-cell and inside-out patch-clamp recordings of heterologously expressed KCa2 channels revealed that AP30663 inhibits KCa2 channels with minor effects on other relevant cardiac ion channels. AP30663 modulates the KCa2.3 channel by right-shifting the Ca2+-activation curve. In isolated guinea pig hearts AP30663 significantly prolonged the atrial effective refractory period (AERP) with minor effects on the QT-interval corrected for heart rate. Similarly, in anaesthetized rats 5 and 10 mg/kg of AP30663 changed the AERP to 130.7±5.4% and 189.9±18.6 of baseline values. The expression quantitative trait loci analyses revealed that the genome wide association studies for AF SNP rs13376333 in KCNN3 is associated with increased mRNA expression of KCNN3 in human atrial appendage tissue. Conclusions AP30663 is a novel negative allosteric modulator of KCa2 channels that concentration-dependently prolonged rodent atrial refractoriness with minor effects on the QT-interval. Moreover, AF associated SNPs in KCNN3 influence KCNN3 mRNA expression in human atrial tissue. These properties support continued development of AP30663 for treatment of AF in man.
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Affiliation(s)
- Bo Hjorth Bentzen
- Acesion Pharma, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sofia Hammami Bomholtz
- Acesion Pharma, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rafel Simó-Vicens
- Acesion Pharma, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lasse Folkersen
- Institute of Biological Psychiatry, Sankt Hans Hospital, Roskilde, Denmark
| | | | - Tobias Speerschneider
- Acesion Pharma, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kalai Mangai Muthukumarasamy
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nils Edvardsson
- Acesion Pharma, Copenhagen, Denmark.,Department of Molecular and Clinical Medicine/Cardiology, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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14
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Citerni C, Kirchhoff J, Olsen LH, Sattler SM, Grunnet M, Edvardsson N, Bentzen BH, Diness JG. Inhibition of K Ca2 and K v11.1 Channels in Pigs With Left Ventricular Dysfunction. Front Pharmacol 2020; 11:556. [PMID: 32435191 PMCID: PMC7219273 DOI: 10.3389/fphar.2020.00556] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 04/14/2020] [Indexed: 12/17/2022] Open
Abstract
Background Inhibition of KCa2 channels, conducting IKCa, can convert atrial fibrillation (AF) to sinus rhythm and protect against its induction. IKCa inhibition has been shown to possess functional atrial selectivity with minor effects on ventricles. Under pathophysiological conditions with ventricular remodeling, however, inhibiting IKCa can exhibit both proarrhythmic and antiarrhythmic ventricular effects. The aim of this study was to evaluate the effects of the IKCa inhibitor AP14145, when given before or after the IKr blocker dofetilide, on cardiac function and ventricular proarrhythmia markers in pigs with or without left ventricular dysfunction (LVD). Methods Landrace pigs were randomized into an AF group (n = 6) and two control groups: SHAM1 (n = 8) and SHAM2 (n = 4). AF pigs were atrially tachypaced (A-TP) for 43 ± 4 days until sustained AF and LVD developed. A-TP and SHAM1 pigs received 20 mg/kg AP14145 followed by 100 µg/kg dofetilide whereas SHAM2 pigs received the same drugs in the opposite order. Proarrhythmic markers such as short-term variability of QT (STVQT) and RR (STVRR) intervals, and the number of premature ventricular complexes (PVCs) were measured at baseline and after administration of drugs. The influence on cardiac function was assessed by measuring cardiac output, stroke volume, and relevant echocardiographic parameters. Results IKCa inhibition by AP14145 did not increase STVQT or STVRR in any of the pigs. IKr inhibition by dofetilide markedly increased STVQT in the A-TP pigs, but not in SHAM operated pigs. Upon infusion of AP14145 the number of PVCs decreased or remained unchanged both when AP14145 was infused after baseline and after dofetilide. Conversely, the number of PVCs increased or remained unchanged upon dofetilide infusion. Neither AP14145 nor dofetilide affected relevant echocardiographic parameters, cardiac output, or stroke volume in any of the groups. Conclusion IKCa inhibition with AP14145 was not proarrhythmic in healthy pigs, or in the presence of LVD resulting from A-TP. In pigs already challenged with 100 µg/kg dofetilide there were no signs of proarrhythmia when 20 mg/kg AP14145 were infused. KCa2 channel inhibition did not affect cardiac function, implying that KCa2 inhibitors can be administered safely also in the presence of LV dysfunction.
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Affiliation(s)
- Carlotta Citerni
- Biomedical Institute, University of Copenhagen, Copenhagen, Denmark.,Acesion Pharma, Copenhagen, Denmark
| | | | - Lisbeth Høier Olsen
- Department of Veterinary Disease Biology, University of Copenhagen, Frederiksberg, Denmark
| | - Stefan Michael Sattler
- Biomedical Institute, University of Copenhagen, Copenhagen, Denmark.,Department of Cardiology, Heart Center, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | | | - Nils Edvardsson
- Acesion Pharma, Copenhagen, Denmark.,Department of Molecular and Clinical Medicine, Sahlgrenska Academy at Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Bo Hjorth Bentzen
- Biomedical Institute, University of Copenhagen, Copenhagen, Denmark.,Acesion Pharma, Copenhagen, Denmark
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15
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Poulsen PC, Schrölkamp M, Bagwan N, Leurs U, Humphries ESA, Bomholzt SH, Nielsen MS, Bentzen BH, Olsen JV, Lundby A. Quantitative proteomics characterization of acutely isolated primary adult rat cardiomyocytes and fibroblasts. J Mol Cell Cardiol 2020; 143:63-70. [PMID: 32325152 DOI: 10.1016/j.yjmcc.2020.04.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/01/2020] [Accepted: 04/15/2020] [Indexed: 12/13/2022]
Abstract
Our heart is comprised of many different cell types that all contribute to cardiac function. An important step in deciphering the molecular complexity of our heart is to decipher the molecular composition of the various cardiac cell types. Here we set out to delineate a comprehensive protein expression profile of the two most prevalent cell types in the heart: cardiomyocytes and cardiac fibroblasts. To this end, we isolated cardiomyocytes and fibroblasts from rat hearts and combined state-of-the-art flow cytometry with high-resolution mass spectrometry to investigate their proteome profiles right after isolation. We measured and quantified 5240 proteins in cardiomyocytes and 6328 proteins in cardiac fibroblasts. In addition to providing a global protein profile for these cardiac cell types, we also present specific findings, such as unique expression of ion channels and transcription factors for each cell type. For instance, we show that the sodium channel Scn7a and the cation channel Trpm7 are expressed in fibroblasts but not in cardiomyocytes, which underscores the importance of investigating the endogenous cell host prior to functional studies. Our dataset represents a valuable resource on protein expression profiles in these two primary cardiac cells types.
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Affiliation(s)
- Pi Camilla Poulsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Maren Schrölkamp
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Navratan Bagwan
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Ulrike Leurs
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Edward S A Humphries
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Sofia Hammami Bomholzt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Morten Schak Nielsen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Bo Hjorth Bentzen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Jesper Velgaard Olsen
- The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark
| | - Alicia Lundby
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark; The Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen N, Denmark.
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16
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Citerni C, Kirchhoff J, Olsen LH, Sattler SM, Gentilini F, Forni M, Zannoni A, Grunnet M, Edvardsson N, Bentzen BH, Diness JG. Characterization of Atrial and Ventricular Structural Remodeling in a Porcine Model of Atrial Fibrillation Induced by Atrial Tachypacing. Front Vet Sci 2020; 7:179. [PMID: 32328502 PMCID: PMC7160334 DOI: 10.3389/fvets.2020.00179] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 03/19/2020] [Indexed: 12/12/2022] Open
Abstract
Background: Atrial fibrillation (AF) is characterized by electrical and structural remodeling. Irregular and/or fast atrio-ventricular (AV) conduction during AF can result in AV dyssynchrony, tachymyopathy, pressure and volume overload with subsequent dilatation, valve regurgitation, and ventricular dysfunction with progression to heart failure. Objective: To gain further insight into the myocardial pathophysiological changes induced by right atrial tachypacing (A-TP) in a large animal model. Methods: A total of 28 Landrace pigs were randomized as 14 into AF-induced A-TP group and 14 pigs to control group. AF pigs were tachypaced for 43 ± 4 days until in sustained AF. Functional remodeling was investigated by echocardiography (after cardioversion to sinus rhythm). Structural remodeling was quantified by histological preparations with picrosirius red and immunohistochemical stainings. Results: A-TP resulted in decreased left ventricular ejection fraction (LVEF) accompanied by increased end-diastolic and end-systolic left atrium (LA) volume and area. In addition, A-TP was associated with mitral valve (MV) regurgitation, diastolic dysfunction and increased atrial and ventricular fibrotic extracellular matrix (ECM). Conclusions: A-TP induced AF with concomitant LV systolic and diastolic dysfunction, increased LA volume and area, and atrial and ventricular fibrosis.
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Affiliation(s)
- Carlotta Citerni
- Biomedical Institute, University of Copenhagen, Copenhagen, Denmark.,Acesion Pharma, Copenhagen, Denmark
| | | | - Lisbeth Høier Olsen
- Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Stefan Michael Sattler
- Biomedical Institute, University of Copenhagen, Copenhagen, Denmark.,Department of Cardiology, Heart Center, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.,Medical Department I, University Hospital Grosshadern, LMU Munich, Munich, Germany
| | - Fabio Gentilini
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | - Monica Forni
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | - Augusta Zannoni
- Department of Veterinary Medical Sciences, University of Bologna, Bologna, Italy
| | | | - Nils Edvardsson
- Acesion Pharma, Copenhagen, Denmark.,Department of Molecular and Clinical Medicine/Cardiology, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Bo Hjorth Bentzen
- Biomedical Institute, University of Copenhagen, Copenhagen, Denmark.,Acesion Pharma, Copenhagen, Denmark
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17
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Diness JG, Kirchhoff JE, Speerschneider T, Abildgaard L, Edvardsson N, Sørensen US, Grunnet M, Bentzen BH. The K Ca2 Channel Inhibitor AP30663 Selectively Increases Atrial Refractoriness, Converts Vernakalant-Resistant Atrial Fibrillation and Prevents Its Reinduction in Conscious Pigs. Front Pharmacol 2020; 11:159. [PMID: 32180722 PMCID: PMC7059611 DOI: 10.3389/fphar.2020.00159] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 02/07/2020] [Indexed: 12/20/2022] Open
Abstract
AIMS To describe the effects of the KCa2 channel inhibitor AP30663 in pigs regarding tolerability, cardiac electrophysiology, pharmacokinetics, atrial functional selectivity, effectiveness in cardioversion of tachy-pacing induced vernakalant-resistant atrial fibrillation (AF), and prevention of reinduction of AF. METHODS AND RESULTS Six healthy pigs with implanted pacemakers and equipped with a Holter monitor were used to compare the effects of increasing doses (0, 5, 10, 15, 20, and 25 mg/kg) of AP30663 on the right atrial effective refractory period (AERP) and on various ECG parameters, including the QT interval. Ten pigs with implanted neurostimulators were long-term atrially tachypaced (A-TP) until sustained vernakalant-resistant AF was present. 20 mg/kg AP30663 was tested to discover if it could successfully convert vernakalant-resistant AF to sinus rhythm (SR) and protect against reinduction of AF. Seven anesthetized pigs were used for pharmacokinetic experiments. Two pigs received an infusion of 20 mg/kg AP30663 over 60 min while five pigs received 5 mg/kg AP30663 over 30 min. Blood samples were collected before, during, and after infusion on AP30663. AP30663 was well-tolerated and prominently increased the AERP in pigs with little effect on ventricular repolarization. Furthermore, it converted A-TP induced AF that had become unresponsive to vernakalant, and it prevented reinduction of AF in pigs. Both a >30 ms increase of the AERP and conversion of AF occurred in different pigs at a free plasma concentration level of around 1.0-1.4 µM of AP30663, which was achieved at a dose level of 5 mg/kg. CONCLUSION AP30663 has shown properties in animals that would be of clinical interest in man.
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Affiliation(s)
| | | | - Tobias Speerschneider
- Department of In Vivo Pharmacology, Acesion Pharma, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lea Abildgaard
- Department of In Vivo Pharmacology, Acesion Pharma, Copenhagen, Denmark
| | - Nils Edvardsson
- Department of In Vivo Pharmacology, Acesion Pharma, Copenhagen, Denmark
- Department of Molecular and Clinical Medicine/Cardiology, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ulrik S. Sørensen
- Department of In Vivo Pharmacology, Acesion Pharma, Copenhagen, Denmark
| | - Morten Grunnet
- Department of In Vivo Pharmacology, Acesion Pharma, Copenhagen, Denmark
| | - Bo Hjorth Bentzen
- Department of In Vivo Pharmacology, Acesion Pharma, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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18
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Hansen TH, Yan Y, Ahlberg G, Vad OB, Refsgaard L, Dos Santos JL, Mutsaers N, Svendsen JH, Olesen MS, Bentzen BH, Schmitt N. A Novel Loss-of-Function Variant in the Chloride Ion Channel Gene Clcn2 Associates with Atrial Fibrillation. Sci Rep 2020; 10:1453. [PMID: 31996765 PMCID: PMC6989500 DOI: 10.1038/s41598-020-58475-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 01/15/2020] [Indexed: 11/09/2022] Open
Abstract
Atrial Fibrillation (AF) is the most common cardiac arrhythmia. Its pathogenesis is complex and poorly understood. Whole exome sequencing of Danish families with AF revealed a novel four nucleotide deletion c.1041_1044del in CLCN2 shared by affected individuals. We aimed to investigate the role of genetic variation of CLCN2 encoding the inwardly rectifying chloride channel ClC-2 as a risk factor for the development of familiar AF. The effect of the CLCN2 variant was evaluated by electrophysiological recordings on transiently transfected cells. We used quantitative PCR to assess CLCN2 mRNA expression levels in human atrial and ventricular tissue samples. The nucleotide deletion CLCN2 c.1041_1044del results in a frame-shift and premature stop codon. The truncated ClC-2 p.V347fs channel does not conduct current. Co-expression with wild-type ClC-2, imitating the heterozygote state of the patients, resulted in a 50% reduction in macroscopic current, suggesting an inability of truncated ClC-2 protein to form channel complexes with wild type channel subunits. Quantitative PCR experiments using human heart tissue from healthy donors demonstrated that CLCN2 is expressed across all four heart chambers. Our genetic and functional data points to a possible link between loss of ClC-2 function and an increased risk of developing AF.
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Affiliation(s)
- Thea Hyttel Hansen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,ALK-Abelló A/S, 2970, Hørsholm, Denmark
| | - Yannan Yan
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gustav Ahlberg
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Laboratory for Molecular Cardiology, Department of Cardiology, The Heart Centre, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Oliver Bundgaard Vad
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Laboratory for Molecular Cardiology, Department of Cardiology, The Heart Centre, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Lena Refsgaard
- Laboratory for Molecular Cardiology, Department of Cardiology, The Heart Centre, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Joana Larupa Dos Santos
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nancy Mutsaers
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jesper Hastrup Svendsen
- Laboratory for Molecular Cardiology, Department of Cardiology, The Heart Centre, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Morten Salling Olesen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Laboratory for Molecular Cardiology, Department of Cardiology, The Heart Centre, Righospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Bo Hjorth Bentzen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicole Schmitt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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19
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Hammami Bomholtz S, Refaat M, Buur Steffensen A, David J, Espinosa K, Nussbaum R, Wojciak J, Hjorth Bentzen B, Scheinman M, Schmitt N. Functional phenotype variations of two novel K
V
7.1 mutations identified in patients with Long QT syndrome. Pacing Clin Electrophysiol 2020; 43:210-216. [DOI: 10.1111/pace.13870] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 12/20/2019] [Accepted: 12/29/2019] [Indexed: 11/30/2022]
Affiliation(s)
- Sofia Hammami Bomholtz
- Danish National Research Foundation Centre for Cardiac ArrhythmiaUniversity of Copenhagen Copenhagen Denmark
- Department of Biomedical SciencesUniversity of Copenhagen Copenhagen Denmark
| | - Marwan Refaat
- Department of Internal Medicine, Division of CardiologyAmerican University of Beirut Medical Center Beirut Lebanon
- Department of Biochemistry and Molecular GeneticsAmerican University of Beirut Beirut Lebanon
| | - Annette Buur Steffensen
- Danish National Research Foundation Centre for Cardiac ArrhythmiaUniversity of Copenhagen Copenhagen Denmark
- Department of Biomedical SciencesUniversity of Copenhagen Copenhagen Denmark
| | - Jens‐Peter David
- Danish National Research Foundation Centre for Cardiac ArrhythmiaUniversity of Copenhagen Copenhagen Denmark
- Department of Biomedical SciencesUniversity of Copenhagen Copenhagen Denmark
| | - Karin Espinosa
- Danish National Research Foundation Centre for Cardiac ArrhythmiaUniversity of Copenhagen Copenhagen Denmark
- Department of Biomedical SciencesUniversity of Copenhagen Copenhagen Denmark
| | - Robert Nussbaum
- Department of MedicineUniversity of California, San Francisco San Francisco California
| | - Julianne Wojciak
- Department of MedicineUniversity of California, San Francisco San Francisco California
| | - Bo Hjorth Bentzen
- Danish National Research Foundation Centre for Cardiac ArrhythmiaUniversity of Copenhagen Copenhagen Denmark
- Department of Biomedical SciencesUniversity of Copenhagen Copenhagen Denmark
| | - Melvin Scheinman
- Department of MedicineUniversity of California, San Francisco San Francisco California
| | - Nicole Schmitt
- Danish National Research Foundation Centre for Cardiac ArrhythmiaUniversity of Copenhagen Copenhagen Denmark
- Department of Biomedical SciencesUniversity of Copenhagen Copenhagen Denmark
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20
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Diness JG, Kirchhoff JE, Abildgaard L, Edvardsson N, Soerensen US, Grunnet M, Bentzen BH. P700The SK channel inhibitor AP30663, converts vernakalant-resistant persistent AF and prevents its reinduction in pigs. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz747.0305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Background
Small conductance Ca2+-activated K+-channels (SK-channels) are a promising new atrial selective target for treatment of atrial fibrillation (AF). AP30663 is a small molecule inhibitor of SK-channels that is currently undergoing clinical trials for treatment of AF. Here we present preclinical data from conscious pigs with persistent AF treated with AP30663.
Purpose
To examine the pharmakokintetics (PK) of AP30663 in anaesthetized pigs and to test whether AP30663 could cardiovert AF that was resistant to treatment by 4 mg/kg vernakalant in pigs.
Methods
A total of 12 Danish landrace pigs (gilts) were used for the experiments (2 for PK and 10 for cardioversion of AF).
Ten conscious pigs with implanted neurostimulators were tachypaced in the right atrium for 17±5 days until persistent AF that did not respond to treatment with 4 mg/kg vernakalant was obtained. After 3±2 days of vernakalant-resistant AF, the pigs received an infusion of 20 mg/kg AP30663 over 60 minutes. During the infusion the pigs remained conscious and the ECG was monitored. If AF reverted within this period, burst pacing with 50 Hz was applied thrice. Cardioversion was considered successful if sustained AF was reverted. Protection against reinduction of AF was considered successful if no episodes of AF lasting for more than 10 minutes could be reinduced by burst pacing.
Results
Six out of ten pigs with vernakalant-resistant AF cardioverted during infusion of 20 mg/kg AP30663 over 60 minutes. Four out of six pigs were protected against re-induction of AF by burst pacing. The average time to cardioversion was 29±18 minutes corresponding to calculated free plasma concentrations of 1.0–1.4 μM AP30663. In all the conscious pigs AP30663 was well tolerated with no adverse events.
The maximal plasma concentration (Cmax) of AP30663 observed at the end of infusion was 4532±844 ng/ml corresponding to an unbound concentration of 1.54±0.29 μM. The plasma concentrations during infusion were described well by first-order kinetics with a half-time of 5.2 minutes, whereas the plasma concentrations after infusion followed Michaeilis-Menten kinetics with a fast half-life of 6.8 minutes and a slow half-life of 93.7 minutes. Thus, it seems that there is a fast distribution to other tissues and an elimination half-life of approximately 90 minutes. The plasma concentration during infusion reached 90% of the steady state concentration after 17 minutes.
Conclusion
In an advanced pig model of persistent AF where clinically relevant doses of vernakalant could no longer convert the AF to SR, AP30663 able to convert the pigs to sinus rhythm and protect against reinduction of AF. No signs of adverse events were observed during or after infusion of AP30663. The SK channel inhibitor AP30663 had a fast distribution and an elimination half-life of approximately 90 minutes. The results support the development of AP30663 for treatment of AF in man.
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Affiliation(s)
| | | | | | | | | | | | - B H Bentzen
- University of Copenhagen, Copenhagen, Denmark
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21
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Bentzen BH, Kirchhoff JE, Skarsfeldt MA, Abildgaard L, Edvardsson N, Soerensen US, Grunnet M, Diness JG. P698The KCa2 channel inhibitor AP14145, but not dofetilide or ondansetron, provides functional atrial selectivity in guinea pig hearts. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz747.0303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Background and purpose
Prolongation of cardiac action potentials is considered antiarrhythmic in the atria but can be proarrhytmic in ventricles if the current carried by Kv11.1-channels (IKr) is inhibited. The current mediated by KCa2-channels, IKCa, is considered a promising new target for treatment of atrial fibrillation.
Selective inhibitors of IKr— (dofetilide) and I-KCa (AP14145) were used to compare the effects on ventricular and atrial repolarisation. Ondansetron which has been reported to be a potent blocker of both IKr and IKCa was included to examine its potential atrial antiarrhythmic properties.
Methods
The expression of KCa2- and Kv11.1-channels in the guinea pig heart was investigated using qPCR. Whole-cell patch clamp technique was used to investigate the effects of dofetilide, AP14145, and ondansetron on IKCa and/or IKr. The effect of dofetilide, AP14145, and ondansetron on atrial and ventricular repolarisation was investigated in isolated hearts. A novel atrial paced in vivo guinea pig model was further validated using AP14145 and dofetilide.
Results
AP14145 increased AERP (29 ms ex vivo and 38 ms in vivo) without prolonging QTcB both ex vivo and in vivo. In contrast, dofetilide increased QTcB (41 ms) and, to a lesser extent, AERP (16 ms) in isolated hearts and prolonged QTcB (61ms) with no effects on AERP in the in vivo guinea pig model. Ondansetron did not inhibit IKCa, but did inhibit IKr in vitro. Ondansetron prolonged ventricular (25 ms), but not atrial repolarisation ex vivo.
Conclusion
IKCa inhibition by AP14145 selectively increased atrial repolarisation whereas IKr inhibition by dofetilide and ondansetron increases ventricular repolarisation to a larger extent than atrial repolarisation. Data support that IKCa inhibition may be of value in treating atrial fibrillation without causing adverse effects in the ventricles.
Acknowledgement/Funding
Innovation Fund Denmark and Wellcome Trust
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Affiliation(s)
- B H Bentzen
- University of Copenhagen, Copenhagen, Denmark
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22
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Bentzen BH, Abildgaard L, Edvardsson NG, Soerensen US, Grunnet M, Diness JG. P703The small conductance Ca2+-activated K+-channel inhibition tool compound AP14145 protected the guinea pig heart from ventricular arrhythmia during hypokalemia whereas dofetilide was pro-arrhythmic. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz747.0308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Background
Hypokalemia is commonly encountered in the clinic. Hypokalemia reduces the cardiac repolarization reserve and causes increases in intracellular calcium. This prolongs the QT-interval and increases the risk of ventricular arrhythmia; a risk that can be further exacerbated by concomitant administration of classical class 3 anti-arrhythmic agents.
Small conductance Ca2+-activated K+-channels (SK-channels) are a promising new atrial selective target for treatment of atrial fibrillation (AF). Under physiological conditions SK channels play an insignificant role in ventricular repolarization. However, this might change under hypokalemia because of concomitant increases in intracellur calcium.
Purpose
To study the effects of SK channel inhibition with the tool compound AP14145 or ICA under hypokalemic conditions as compared to the class 3 anti-arrhythmic agent dofetilide and time matched controls (TMC).
Methods
Guinea pig hearts were isolated and retrogradely perfused with normokalemic (4.5 mM K+) Krebs-Henseleit solution, followed by perfusion with drug or vehicle control. The perfusion was then changed to hypokalemic solution (2.5 mM K+) in presence of drug for 20 min, followed by 20 min perfusion with normokalemic solution in presence of drug. A total of 24 animals were included in the study and randomly assigned to 4 groups: ICA, AP14145, dofetilide or TMC. QT-interval, ventricular effective refractory period, extra systoles and incidence of ventricular tachycardia (VT) or fibrillation (VF) were recorded for each perfusion period.
Results
Hypokalemia caused a small increase in QT-interval. Application of SK channel inhibitors did not cause further changes, whereas dofetilide prolonged QT compared to hypokalemia alone. During hypokalemia 3 out of 6 hearts in the TMC group developed VF (one spontaneously, two following S1S2 stimulation) whereas 4 out of 6 hearts developed VF in the dofetilide group (one spontaneously, three following S1S2 stimulation). In comparison only 1 heart out of 6 developed VF when treated with the SK channel inhibitor ICA (spontaneously) or AP14145 (following S1S2 stimulation).
Conclusion
Hypokalemia was associated with an increased risk of VF, an effect that was exaggerated by co-administration of dofetilide. In comparison, the structurally and functionally different SK channel inhibitors, ICA and AP14145, protected the heart from hypokalemia induced VF. These results with the tool compound AP14145 support that SK inhibition may be associated with a better safety and tolerability profile than dofetilide.
Acknowledgement/Funding
Innovation Fund Denmark
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Affiliation(s)
- B H Bentzen
- University of Copenhagen, Copenhagen, Denmark
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23
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Bomholtz SH, Simo-Vicens R, Abildgaard L, Edvardsson NG, Soerensen US, Grunnet M, Diness JG, Bentzen BH. P699Mechanisms of action of the small conductance Ca2+-activated K+-channel modulator AP30663, a novel compound being developed for treatment of atrial fibrillation in man. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz747.0304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
Small conductance Ca2+-activated K+-channels (SK-channels) are a promising new atrial selective target for treatment of atrial fibrillation (AF). AP30663 is a small molecule inhibitor of SK-channels that is effective in converting vernakalant-resistant AF in tachy-paced pigs. Detailed understanding of the molecular mechanism of AP30663 is important for the development of SK channel inhibition for use in man.
Purpose
To establish the electrophysiological profile, mechanism of action and efficacy in prolonging atrial refractoriness ex vivo of AP30663.
Methods
AP30663 potency and mechanism of action were established by whole cell and inside-out patch clamp recordings of expressed SK channels. The ion channel selectivity profile of AP30663 was investigated on heterologous expressed channels. Effects of AP30663 or vehicle (DMSO) on atrial refractoriness (AERP) and ventricular repolarization (QTcB) were investigated on isolated perfused guinea pig hearts.
Results
AP30663 was found to be a selective negative allosteric modulator of SK channels (IC50=0.77±x0.13 μM) with no or minor effects on a panel of other cardiac ion channels, including hERG/KV11.1, (IKr), KV7.1/KCNE1 (IKs), KV4.3/KChiP2 (Ito), Kir2.1 (IK1), Kir3.1/Kir3.4 (IKACh), KV1.5 (IKur), NaV1.5 (INa) and CaV1.2 (ICa). AP30663 inhibited the SK-channel by right-shifting the calcium activation curve of the SK-channel (the EC50 of Ca2+ increased from 0.43±0.02 μM (control, n=6) to 1.37±0.05 μM (in the presence of 7μM AP30663, n=6).
In isolated guinea pig hearts, administration of vehicle had no effect on AERP or QTcB. AP30663 significantly prolonged the AERP in 3 μM (to 131±6% of baseline) and 10 μM (to 165±3% of baseline) without any effects on the QTcB.
Conclusion
AP30663 is a selective negative allosteric modulator of SK channels, acting by means of shifting the calcium dependence of SK-channel activation. AP30663 prolonged atrial refractoriness without affecting the QT-interval in isolated perfused heart preparations. These properties support continued development of AP30663 for treatment of AF in man.
Acknowledgement/Funding
Innovation Fund Denmark, Wellcome Trust
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Affiliation(s)
| | | | | | | | | | | | | | - B H Bentzen
- University of Copenhagen, Copenhagen, Denmark
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24
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Kirchhoff JE, Skarsfeldt MA, Muthukumarasamy KM, Simó-Vicens R, Bomholtz SH, Abildgaard L, Jespersen T, Sørensen US, Grunnet M, Bentzen BH, Diness JG. The K Ca2 Channel Inhibitor AP14145, But Not Dofetilide or Ondansetron, Provides Functional Atrial Selectivity in Guinea Pig Hearts. Front Pharmacol 2019; 10:668. [PMID: 31275147 PMCID: PMC6593233 DOI: 10.3389/fphar.2019.00668] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 05/23/2019] [Indexed: 11/13/2022] Open
Abstract
Background and Purpose: Prolongation of cardiac action potentials is considered antiarrhythmic in the atria but can be proarrhythmic in ventricles if the current carried by Kv11.1-channels (IKr) is inhibited. The current mediated by KCa2-channels, IKCa, is considered a promising new target for treatment of atrial fibrillation (AF). Selective inhibitors of IKr (dofetilide) and IKCa (AP14145) were used to compare the effects on ventricular and atrial repolarization. Ondansetron, which has been reported to be a potent blocker of both IKr and IKCa, was included to examine its potential atrial antiarrhythmic properties. Experimental Approach: The expression of KCa2- and Kv11.1-channels in the guinea pig heart was investigated using quantitative polymerase chain reaction (qPCR). Whole-cell patch clamp technique was used to investigate the effects of dofetilide, AP14145, and ondansetron on IKCa and/or IKr. The effect of dofetilide, AP14145, and ondansetron on atrial and ventricular repolarization was investigated in isolated hearts. A novel atrial paced in vivo guinea pig model was further validated using AP14145 and dofetilide. Key Results: AP14145 increased the atrial effective refractory period (AERP) without prolonging the QT interval with Bazett's correction for heart rate (QTcB) both ex vivo and in vivo. In contrast, dofetilide increased QTcB and, to a lesser extent, AERP in isolated hearts and prolonged QTcB with no effects on AERP in the in vivo guinea pig model. Ondansetron did not inhibit IKCa, but did inhibit IKr in vitro. Ondansetron prolonged ventricular, but not atrial repolarization ex vivo. Conclusion and Implications: IKCa inhibition by AP14145 selectively increases atrial repolarization, whereas IKr inhibition by dofetilide and ondansetron increases ventricular repolarization to a larger extent than atrial repolarization.
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Affiliation(s)
| | - Mark Alexander Skarsfeldt
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kalai Mangai Muthukumarasamy
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rafel Simó-Vicens
- Acesion Pharma, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sofia Hammami Bomholtz
- Acesion Pharma, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Thomas Jespersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | | | - Bo Hjorth Bentzen
- Acesion Pharma, Copenhagen, Denmark.,Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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25
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Sloth CK, Denti F, Schmitt N, Bentzen BH, Fagerberg C, Vissing J, Gaist D. Homozygosity for SCN4A Arg1142Gln causes congenital myopathy with variable disease expression. Neurol Genet 2018; 4:e267. [PMID: 30283817 PMCID: PMC6167177 DOI: 10.1212/nxg.0000000000000267] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 07/26/2018] [Indexed: 11/20/2022]
Affiliation(s)
- Christine K Sloth
- Department of Neurology (C.K.S., D.G.), Odense University Hospital; and Department of Clinical Research (C.K.S., D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense; Department of Biomedical Sciences (F.D., N.S., B.H.B.), Faculty of Health and Medical Sciences, University of Copenhagen; Department of Clinical Genetics (C.F.), Odense University Hospital; and Copenhagen Neuromuscular Center, Department of Neurology (J.V.), Rigshospitalet, University of Copenhagen, Denmark
| | - Federico Denti
- Department of Neurology (C.K.S., D.G.), Odense University Hospital; and Department of Clinical Research (C.K.S., D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense; Department of Biomedical Sciences (F.D., N.S., B.H.B.), Faculty of Health and Medical Sciences, University of Copenhagen; Department of Clinical Genetics (C.F.), Odense University Hospital; and Copenhagen Neuromuscular Center, Department of Neurology (J.V.), Rigshospitalet, University of Copenhagen, Denmark
| | - Nicole Schmitt
- Department of Neurology (C.K.S., D.G.), Odense University Hospital; and Department of Clinical Research (C.K.S., D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense; Department of Biomedical Sciences (F.D., N.S., B.H.B.), Faculty of Health and Medical Sciences, University of Copenhagen; Department of Clinical Genetics (C.F.), Odense University Hospital; and Copenhagen Neuromuscular Center, Department of Neurology (J.V.), Rigshospitalet, University of Copenhagen, Denmark
| | - Bo Hjorth Bentzen
- Department of Neurology (C.K.S., D.G.), Odense University Hospital; and Department of Clinical Research (C.K.S., D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense; Department of Biomedical Sciences (F.D., N.S., B.H.B.), Faculty of Health and Medical Sciences, University of Copenhagen; Department of Clinical Genetics (C.F.), Odense University Hospital; and Copenhagen Neuromuscular Center, Department of Neurology (J.V.), Rigshospitalet, University of Copenhagen, Denmark
| | - Christina Fagerberg
- Department of Neurology (C.K.S., D.G.), Odense University Hospital; and Department of Clinical Research (C.K.S., D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense; Department of Biomedical Sciences (F.D., N.S., B.H.B.), Faculty of Health and Medical Sciences, University of Copenhagen; Department of Clinical Genetics (C.F.), Odense University Hospital; and Copenhagen Neuromuscular Center, Department of Neurology (J.V.), Rigshospitalet, University of Copenhagen, Denmark
| | - John Vissing
- Department of Neurology (C.K.S., D.G.), Odense University Hospital; and Department of Clinical Research (C.K.S., D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense; Department of Biomedical Sciences (F.D., N.S., B.H.B.), Faculty of Health and Medical Sciences, University of Copenhagen; Department of Clinical Genetics (C.F.), Odense University Hospital; and Copenhagen Neuromuscular Center, Department of Neurology (J.V.), Rigshospitalet, University of Copenhagen, Denmark
| | - David Gaist
- Department of Neurology (C.K.S., D.G.), Odense University Hospital; and Department of Clinical Research (C.K.S., D.G.), Faculty of Health Sciences, University of Southern Denmark, Odense; Department of Biomedical Sciences (F.D., N.S., B.H.B.), Faculty of Health and Medical Sciences, University of Copenhagen; Department of Clinical Genetics (C.F.), Odense University Hospital; and Copenhagen Neuromuscular Center, Department of Neurology (J.V.), Rigshospitalet, University of Copenhagen, Denmark
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26
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Denti F, Bentzen BH, Wojciak J, Thomsen NM, Scheinman M, Schmitt N. Multiple genetic variations in sodium channel subunits in a case of sudden infant death syndrome. Pacing Clin Electrophysiol 2018; 41:620-626. [PMID: 29572929 DOI: 10.1111/pace.13328] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 02/15/2018] [Accepted: 02/25/2018] [Indexed: 12/20/2022]
Abstract
BACKGROUND Dysfunction of NaV 1.5 encoded by SCN5A accounts for approximately half of the channelopathic SIDS cases. We investigated the functional effect of two gene variants identified in the same patient, one in SCN5A and one in SCN1Bb. The aim of the study was to risk stratify the proband's family. METHODS The family was referred for cardiovascular genetic evaluation to assess familial risk of cardiac disease. Functional analysis of the identified variants was performed with patch-clamp electrophysiology in HEK293 cells. RESULTS A 16-month-old healthy boy died suddenly in the context of nonspecific illness and possible fever. Postmortem genetic testing revealed variants in the SCN5A and SCN1Bb genes. The proband's father carries the same variants but is asymptomatic. Electrophysiological analysis of the NaV 1.5_1281X truncation revealed complete loss-of-function of the channel. Coexpression of NaV 1.5 with NaV β1b significantly increased INa density when compared to NaV 1.5 alone. The NaV β1b _V268I variant abolished this INa density increase. Moreover, it shifted the activation curve toward more depolarized potentials. CONCLUSIONS Genetic variation of both sodium channel and its modifiers may contribute to sudden unexplained death in childhood. However, the asymptomatic father suggests that genetic variation of these genes is not sufficient to cause sudden death or clinically detectable SCN5A phenotypes.
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Affiliation(s)
- Federico Denti
- Danish National Research Foundation Centre for Cardiac Arrhythmia and Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bo Hjorth Bentzen
- Danish National Research Foundation Centre for Cardiac Arrhythmia and Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Julianne Wojciak
- Department of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Nancy Mutsaers Thomsen
- Danish National Research Foundation Centre for Cardiac Arrhythmia and Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Melvin Scheinman
- Department of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Nicole Schmitt
- Danish National Research Foundation Centre for Cardiac Arrhythmia and Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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27
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Denti F, Paludan-Müller C, Olesen SP, Haunsø S, Svendsen JH, Olesen MS, Bentzen BH, Schmitt N. Functional consequences of genetic variation in sodium channel modifiers in early onset lone atrial fibrillation. Per Med 2018; 15:93-102. [DOI: 10.2217/pme-2017-0076] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aim: We investigated the effect of variants in genes encoding sodium channel modifiers SNTA1 and GPD1L found in early onset atrial fibrillation (AF) patients. Patients & methods: Genetic screening in patients with early onset lone AF revealed three variants in GPD1L and SNTA1 in three AF patients. Functional analysis was performed by patch-clamp electrophysiology. Results: Co-expression of GPD1L or its p.A326E variant with NaV1.5 did not alter INa density or current kinetics. SNTA1 shifted the peak-current by -5 mV. The SNTA1-p.A257G variant significantly increased INa. SNTA1-p.P74L did not produce functional changes. Conclusion: Although genetic variation of sodium channel modifiers may contribute to development of AF at a molecular level, it is unlikely a monogenic cause of the disease.
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Affiliation(s)
- Federico Denti
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Christian Paludan-Müller
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Laboratory for Molecular Cardiology, Department of Cardiology, The Heart Centre, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Søren-Peter Olesen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Stig Haunsø
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Laboratory for Molecular Cardiology, Department of Cardiology, The Heart Centre, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health & Medical Sciences, University of Copenhagen, Denmark
| | - Jesper Hastrup Svendsen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Laboratory for Molecular Cardiology, Department of Cardiology, The Heart Centre, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
- Department of Clinical Medicine, Faculty of Health & Medical Sciences, University of Copenhagen, Denmark
| | - Morten Salling Olesen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Laboratory for Molecular Cardiology, Department of Cardiology, The Heart Centre, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Bo Hjorth Bentzen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nicole Schmitt
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health & Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Diness JG, Skibsbye L, Simó-Vicens R, Santos JL, Lundegaard P, Citerni C, Sauter DRP, Bomholtz SH, Svendsen JH, Olesen SP, Sørensen US, Jespersen T, Grunnet M, Bentzen BH. Termination of Vernakalant-Resistant Atrial Fibrillation by Inhibition of Small-Conductance Ca 2+-Activated K + Channels in Pigs. Circ Arrhythm Electrophysiol 2017; 10:CIRCEP.117.005125. [PMID: 29018164 PMCID: PMC5647113 DOI: 10.1161/circep.117.005125] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 08/21/2017] [Indexed: 11/17/2022]
Abstract
Supplemental Digital Content is available in the text. Background Evidence has emerged that small-conductance Ca2+-activated K+ (SK) channels constitute a new target for treatment of atrial fibrillation (AF). SK channels are predominantly expressed in the atria as compared with the ventricles. Various marketed antiarrhythmic drugs are limited by ventricular adverse effects and efficacy loss as AF progresses. Methods and Results A total of 43 pigs were used for the studies. AF reversion in conscious long-term tachypaced pigs: Pigs were subjected to atrial tachypacing (7 Hz) until they developed sustained AF that could not be reverted by vernakalant 4 mg/kg (18.8±3.3 days of atrial tachypacing). When the SK channel inhibitor AP14145 was tested in these animals, vernakalant-resistant AF was reverted to sinus rhythm, and reinduction of AF by burst pacing (50 Hz) was prevented in 8 of 8 pigs. Effects on refractory period and AF duration in open chest pigs: The effects of AP14145 and vernakalant on the effective refractory periods and acute burst pacing-induced AF were examined in anaesthetized open chest pigs. Both vernakalant and AP14145 significantly prolonged atrial refractoriness and reduced AF duration without affecting the ventricular refractoriness or blood pressure in pigs subjected to 7 days atrial tachypacing, as well as in sham-operated control pigs. Conclusions SK currents play a role in porcine atrial repolarization, and pharmacological inhibition of these with AP14145 demonstrates antiarrhythmic effects in a vernakalant-resistant porcine model of AF. These results suggest SK channel blockers as potentially interesting anti-AF drugs.
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Affiliation(s)
- Jonas Goldin Diness
- From the Acesion Pharma, Copenhagen, Denmark (J.G.D., R.S.-V., C.C., D.R.P.S., S.H.B., U.S.S., M.G., B.H.B.); Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (L.S., J.L.S., P.L., D.R.P.S., S.-P.O., T.J., M.G., B.H.B.); and the Heart Centre, Rigshospitalet, Copenhagen, Denmark (J.H.S.).
| | - Lasse Skibsbye
- From the Acesion Pharma, Copenhagen, Denmark (J.G.D., R.S.-V., C.C., D.R.P.S., S.H.B., U.S.S., M.G., B.H.B.); Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (L.S., J.L.S., P.L., D.R.P.S., S.-P.O., T.J., M.G., B.H.B.); and the Heart Centre, Rigshospitalet, Copenhagen, Denmark (J.H.S.)
| | - Rafel Simó-Vicens
- From the Acesion Pharma, Copenhagen, Denmark (J.G.D., R.S.-V., C.C., D.R.P.S., S.H.B., U.S.S., M.G., B.H.B.); Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (L.S., J.L.S., P.L., D.R.P.S., S.-P.O., T.J., M.G., B.H.B.); and the Heart Centre, Rigshospitalet, Copenhagen, Denmark (J.H.S.)
| | - Joana Larupa Santos
- From the Acesion Pharma, Copenhagen, Denmark (J.G.D., R.S.-V., C.C., D.R.P.S., S.H.B., U.S.S., M.G., B.H.B.); Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (L.S., J.L.S., P.L., D.R.P.S., S.-P.O., T.J., M.G., B.H.B.); and the Heart Centre, Rigshospitalet, Copenhagen, Denmark (J.H.S.)
| | - Pia Lundegaard
- From the Acesion Pharma, Copenhagen, Denmark (J.G.D., R.S.-V., C.C., D.R.P.S., S.H.B., U.S.S., M.G., B.H.B.); Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (L.S., J.L.S., P.L., D.R.P.S., S.-P.O., T.J., M.G., B.H.B.); and the Heart Centre, Rigshospitalet, Copenhagen, Denmark (J.H.S.)
| | - Carlotta Citerni
- From the Acesion Pharma, Copenhagen, Denmark (J.G.D., R.S.-V., C.C., D.R.P.S., S.H.B., U.S.S., M.G., B.H.B.); Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (L.S., J.L.S., P.L., D.R.P.S., S.-P.O., T.J., M.G., B.H.B.); and the Heart Centre, Rigshospitalet, Copenhagen, Denmark (J.H.S.)
| | - Daniel Rafael Peter Sauter
- From the Acesion Pharma, Copenhagen, Denmark (J.G.D., R.S.-V., C.C., D.R.P.S., S.H.B., U.S.S., M.G., B.H.B.); Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (L.S., J.L.S., P.L., D.R.P.S., S.-P.O., T.J., M.G., B.H.B.); and the Heart Centre, Rigshospitalet, Copenhagen, Denmark (J.H.S.)
| | - Sofia Hammami Bomholtz
- From the Acesion Pharma, Copenhagen, Denmark (J.G.D., R.S.-V., C.C., D.R.P.S., S.H.B., U.S.S., M.G., B.H.B.); Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (L.S., J.L.S., P.L., D.R.P.S., S.-P.O., T.J., M.G., B.H.B.); and the Heart Centre, Rigshospitalet, Copenhagen, Denmark (J.H.S.)
| | - Jesper Hastrup Svendsen
- From the Acesion Pharma, Copenhagen, Denmark (J.G.D., R.S.-V., C.C., D.R.P.S., S.H.B., U.S.S., M.G., B.H.B.); Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (L.S., J.L.S., P.L., D.R.P.S., S.-P.O., T.J., M.G., B.H.B.); and the Heart Centre, Rigshospitalet, Copenhagen, Denmark (J.H.S.)
| | - Søren-Peter Olesen
- From the Acesion Pharma, Copenhagen, Denmark (J.G.D., R.S.-V., C.C., D.R.P.S., S.H.B., U.S.S., M.G., B.H.B.); Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (L.S., J.L.S., P.L., D.R.P.S., S.-P.O., T.J., M.G., B.H.B.); and the Heart Centre, Rigshospitalet, Copenhagen, Denmark (J.H.S.)
| | - Ulrik S Sørensen
- From the Acesion Pharma, Copenhagen, Denmark (J.G.D., R.S.-V., C.C., D.R.P.S., S.H.B., U.S.S., M.G., B.H.B.); Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (L.S., J.L.S., P.L., D.R.P.S., S.-P.O., T.J., M.G., B.H.B.); and the Heart Centre, Rigshospitalet, Copenhagen, Denmark (J.H.S.)
| | - Thomas Jespersen
- From the Acesion Pharma, Copenhagen, Denmark (J.G.D., R.S.-V., C.C., D.R.P.S., S.H.B., U.S.S., M.G., B.H.B.); Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (L.S., J.L.S., P.L., D.R.P.S., S.-P.O., T.J., M.G., B.H.B.); and the Heart Centre, Rigshospitalet, Copenhagen, Denmark (J.H.S.)
| | - Morten Grunnet
- From the Acesion Pharma, Copenhagen, Denmark (J.G.D., R.S.-V., C.C., D.R.P.S., S.H.B., U.S.S., M.G., B.H.B.); Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (L.S., J.L.S., P.L., D.R.P.S., S.-P.O., T.J., M.G., B.H.B.); and the Heart Centre, Rigshospitalet, Copenhagen, Denmark (J.H.S.)
| | - Bo Hjorth Bentzen
- From the Acesion Pharma, Copenhagen, Denmark (J.G.D., R.S.-V., C.C., D.R.P.S., S.H.B., U.S.S., M.G., B.H.B.); Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark (L.S., J.L.S., P.L., D.R.P.S., S.-P.O., T.J., M.G., B.H.B.); and the Heart Centre, Rigshospitalet, Copenhagen, Denmark (J.H.S.)
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Liin SI, Larsson JE, Barro-Soria R, Bentzen BH, Larsson HP. Fatty acid analogue N-arachidonoyl taurine restores function of I Ks channels with diverse long QT mutations. eLife 2016; 5. [PMID: 27690226 PMCID: PMC5081249 DOI: 10.7554/elife.20272] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 09/28/2016] [Indexed: 01/08/2023] Open
Abstract
About 300 loss-of-function mutations in the IKs channel have been identified in patients with Long QT syndrome and cardiac arrhythmia. How specific mutations cause arrhythmia is largely unknown and there are no approved IKs channel activators for treatment of these arrhythmias. We find that several Long QT syndrome-associated IKs channel mutations shift channel voltage dependence and accelerate channel closing. Voltage-clamp fluorometry experiments and kinetic modeling suggest that similar mutation-induced alterations in IKs channel currents may be caused by different molecular mechanisms. Finally, we find that the fatty acid analogue N-arachidonoyl taurine restores channel gating of many different mutant channels, even though the mutations are in different domains of the IKs channel and affect the channel by different molecular mechanisms. N-arachidonoyl taurine is therefore an interesting prototype compound that may inspire development of future IKs channel activators to treat Long QT syndrome caused by diverse IKs channel mutations. DOI:http://dx.doi.org/10.7554/eLife.20272.001 Every heartbeat relies on an electric wave that travels through the heart. This wave must reach different parts of the heart in a specific sequence to ensure that the heart muscle cells contract in a coordinated manner. Such coordinated contractions enable the heart to pump enough blood around the body. By allowing specific ions to flow into or out of the heart muscle cell, proteins called ion channels in the cell membrane generate the electric wave, keep it going and stop it. One such protein called the IKs channel controls the flow of potassium ions, and in doing so stops the electric wave in heart muscle cells. About 300 different mutations in the IKs channel have been shown to cause abnormal heart rhythms in individuals with a disorder called long QT syndrome. People with this condition may suddenly black out because their heart develops prolonged electric waves that prevent blood from being pumped properly. To investigate how mutations in the IKs channel produce heart rhythm abnormalities, Liin et al. genetically engineered the egg cells of African clawed frogs to have one of eight mutant forms of the human IKs channel. Studying these channels revealed that the mutations reduce how well the channels work in a wide variety of ways. However, treating the cells with a particular fatty acid helped to normalize how each of the mutant channels worked. Therefore, variants of the fatty acid could potentially form a useful treatment for people with heart rhythm problems caused by mutations in the IKs channel. More studies are needed to confirm whether the fatty acid is as effective at combating the effects of the mutations in whole hearts and animals. As ion channels related to the IKs channel are found in many types of cells, it is also important to investigate whether treatment with the fatty acid could cause any side effects that affect other organs. DOI:http://dx.doi.org/10.7554/eLife.20272.002
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Affiliation(s)
- Sara I Liin
- Department of Physiology and Biophysics, University of Miami, Miami, United States.,Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Johan E Larsson
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - Rene Barro-Soria
- Department of Physiology and Biophysics, University of Miami, Miami, United States
| | - Bo Hjorth Bentzen
- The Danish Arrhythmia Research Centre, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - H Peter Larsson
- Department of Physiology and Biophysics, University of Miami, Miami, United States
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Liin SI, Karlsson U, Bentzen BH, Schmitt N, Elinder F. Polyunsaturated fatty acids are potent openers of human M-channels expressed in Xenopus laevis oocytes. Acta Physiol (Oxf) 2016; 218:28-37. [PMID: 26914447 DOI: 10.1111/apha.12663] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 11/26/2015] [Accepted: 02/18/2016] [Indexed: 11/26/2022]
Abstract
AIM Polyunsaturated fatty acids have been reported to reduce neuronal excitability, in part by promoting inactivation of voltage-gated sodium and calcium channels. Effects on neuronal potassium channels are less explored and experimental data ambiguous. The aim of this study was to investigate anti-excitable effects of polyunsaturated fatty acids on the neuronal M-channel, important for setting the resting membrane potential in hippocampal and dorsal root ganglion neurones. METHODS Effects of fatty acids and fatty acid analogues on mouse dorsal root ganglion neurones and on the human KV 7.2/3 channel expressed in Xenopus laevis oocytes were studied using electrophysiology. RESULTS Extracellular application of physiologically relevant concentrations of the polyunsaturated fatty acid docosahexaenoic acid hyperpolarized the resting membrane potential (-2.4 mV by 30 μm) and increased the threshold current to evoke action potentials in dorsal root ganglion neurones. The polyunsaturated fatty acids docosahexaenoic acid, α-linolenic acid and eicosapentaenoic acid facilitated opening of the human M-channel, comprised of the heteromeric human KV 7.2/3 channel expressed in Xenopus oocytes, by shifting the conductance-vs.-voltage curve towards more negative voltages (by -7.4 to -11.3 mV by 70 μm). Uncharged docosahexaenoic acid methyl ester and monounsaturated oleic acid did not facilitate opening of the human KV 7.2/3 channel. CONCLUSIONS These findings suggest that circulating polyunsaturated fatty acids, with a minimum requirement of multiple double bonds and a charged carboxyl group, dampen excitability by opening neuronal M-channels. Collectively, our data bring light to the molecular targets of polyunsaturated fatty acids and thus a possible mechanism by which polyunsaturated fatty acids reduce neuronal excitability.
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Affiliation(s)
- Sara I Liin
- Department of Clinical and Experimental Medicine; Linköping University; Sweden
| | - Urban Karlsson
- Department of Clinical and Experimental Medicine; Linköping University; Sweden
| | - Bo Hjorth Bentzen
- Danish National Research Foundation Centre for Cardiac Arrhythmia and Department of Biomedical Sciences; University of Copenhagen; Denmark
| | - Nicole Schmitt
- Danish National Research Foundation Centre for Cardiac Arrhythmia and Department of Biomedical Sciences; University of Copenhagen; Denmark
| | - Fredrik Elinder
- Department of Clinical and Experimental Medicine; Linköping University; Sweden
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31
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Nielsen JB, Bentzen BH, Olesen MS, David JP, Olesen SP, Haunsø S, Svendsen JH, Schmitt N. Gain-of-function mutations in potassium channel subunit KCNE2 associated with early-onset lone atrial fibrillation. Biomark Med 2014; 8:557-70. [PMID: 24796621 DOI: 10.2217/bmm.13.137] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
AIMS Atrial fibrillation (AF) is the most common cardiac arrhythmia. Disturbances in cardiac potassium conductance are considered as one of the disease mechanisms in AF. We aimed to investigate if mutations in potassium-channel β-subunits KCNE2 and KCNE3 are associated with early-onset lone AF. METHODS & RESULTS The coding regions of KCNE2 and KCNE3 were bidirectionally sequenced in 192 unrelated patients diagnosed with early-onset lone AF (<40 years). Two nonsynonymous missense mutations were identified in KCNE2 (M23L and I57T). Both mutations were absent in a healthy control group (n=1500 alleles). Electrophysiological investigations were performed for both mutations in combination with candidate pore-forming α-subunits KV7.1, KV11.1, KV4.3 and KV1.5. A significant gain-of-function effect was observed upon coexpression with KV7.1 and KV7.1+KCNE1. Confocal imaging found no differences in subcellular localization. No disease-suspected mutations were identified in KCNE3. CONCLUSION We identified two KCNE2 gain-of-function missense mutations that seem to increase the susceptibility of early-onset lone AF. These results confirm previous findings indicating that gain-of-function in the slow delayed rectifier potassium current might be involved in the pathogenesis of AF.
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Affiliation(s)
- Jonas Bille Nielsen
- Danish National Research Foundation Centre for Cardiac Arrhythmia (DARC), Copenhagen, Denmark
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Jepps TA, Bentzen BH, Stott JB, Povstyan OV, Sivaloganathan K, Dalby-Brown W, Greenwood IA. Vasorelaxant effects of novel Kv 7.4 channel enhancers ML213 and NS15370. Br J Pharmacol 2014; 171:4413-24. [PMID: 24909207 DOI: 10.1111/bph.12805] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Revised: 04/25/2014] [Accepted: 05/14/2014] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE The KCNQ-encoded voltage-gated potassium channel family (Kv 7.1-Kv 7.5) are established regulators of smooth muscle contractility, where Kv 7.4 and Kv 7.5 predominate. Various Kv 7.2-7.5 channel enhancers have been developed that have been shown to cause a vasorelaxation in both rodent and human blood vessels. Recently, two novel Kv 7 channel enhancers have been identified, ML213 and NS15370, that show increased potency, particularly on Kv 7.4 channels. The aim of this study was to characterize the effects of these novel enhancers in different rat blood vessels and compare them with Kv 7 enhancers (S-1, BMS204352, retigabine) described previously. We also sought to determine the binding sites of the new Kv 7 enhancers. KEY RESULTS Both ML213 and NS15370 relaxed segments of rat thoracic aorta, renal artery and mesenteric artery in a concentration-dependent manner. In the mesenteric artery ML213 and NS15370 displayed EC50 s that were far lower than other Kv 7 enhancers tested. Current-clamp experiments revealed that both novel enhancers, at low concentrations, caused significant hyperpolarization in mesenteric artery smooth muscle cells. In addition, we determined that the stimulatory effect of these enhancers relied on a tryptophan residue located in the S5 domain, which is the same binding site for the other Kv 7 enhancers tested in this study. CONCLUSIONS AND IMPLICATIONS This study has identified and characterized ML213 and NS15370 as potent vasorelaxants in different blood vessels, thereby highlighting these new compounds as potential therapeutics for various smooth muscle disorders.
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Affiliation(s)
- T A Jepps
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Soltysinska E, Bentzen BH, Barthmes M, Hattel H, Thrush AB, Harper ME, Qvortrup K, Larsen FJ, Schiffer TA, Losa-Reyna J, Straubinger J, Kniess A, Thomsen MB, Brüggemann A, Fenske S, Biel M, Ruth P, Wahl-Schott C, Boushel RC, Olesen SP, Lukowski R. KCNMA1 encoded cardiac BK channels afford protection against ischemia-reperfusion injury. PLoS One 2014; 9:e103402. [PMID: 25072914 PMCID: PMC4114839 DOI: 10.1371/journal.pone.0103402] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 07/01/2014] [Indexed: 12/18/2022] Open
Abstract
Mitochondrial potassium channels have been implicated in myocardial protection mediated through pre-/postconditioning. Compounds that open the Ca2+- and voltage-activated potassium channel of big-conductance (BK) have a pre-conditioning-like effect on survival of cardiomyocytes after ischemia/reperfusion injury. Recently, mitochondrial BK channels (mitoBKs) in cardiomyocytes were implicated as infarct-limiting factors that derive directly from the KCNMA1 gene encoding for canonical BKs usually present at the plasma membrane of cells. However, some studies challenged these cardio-protective roles of mitoBKs. Herein, we present electrophysiological evidence for paxilline- and NS11021-sensitive BK-mediated currents of 190 pS conductance in mitoplasts from wild-type but not BK-/- cardiomyocytes. Transmission electron microscopy of BK-/- ventricular muscles fibres showed normal ultra-structures and matrix dimension, but oxidative phosphorylation capacities at normoxia and upon re-oxygenation after anoxia were significantly attenuated in BK-/- permeabilized cardiomyocytes. In the absence of BK, post-anoxic reactive oxygen species (ROS) production from cardiomyocyte mitochondria was elevated indicating that mitoBK fine-tune the oxidative state at hypoxia and re-oxygenation. Because ROS and the capacity of the myocardium for oxidative metabolism are important determinants of cellular survival, we tested BK-/- hearts for their response in an ex-vivo model of ischemia/reperfusion (I/R) injury. Infarct areas, coronary flow and heart rates were not different between wild-type and BK-/- hearts upon I/R injury in the absence of ischemic pre-conditioning (IP), but differed upon IP. While the area of infarction comprised 28±3% of the area at risk in wild-type, it was increased to 58±5% in BK-/- hearts suggesting that BK mediates the beneficial effects of IP. These findings suggest that cardiac BK channels are important for proper oxidative energy supply of cardiomyocytes at normoxia and upon re-oxygenation after prolonged anoxia and that IP might indeed favor survival of the myocardium upon I/R injury in a BK-dependent mode stemming from both mitochondrial post-anoxic ROS modulation and non-mitochondrial localizations.
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MESH Headings
- Animals
- Cell Hypoxia
- Disease Models, Animal
- Energy Metabolism
- Indoles/pharmacology
- Ischemic Preconditioning
- Large-Conductance Calcium-Activated Potassium Channel alpha Subunits/genetics
- Large-Conductance Calcium-Activated Potassium Channel alpha Subunits/metabolism
- Large-Conductance Calcium-Activated Potassium Channels/chemistry
- Large-Conductance Calcium-Activated Potassium Channels/genetics
- Large-Conductance Calcium-Activated Potassium Channels/metabolism
- Membrane Potential, Mitochondrial/drug effects
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mitochondria, Heart/metabolism
- Muscle Fibers, Skeletal/ultrastructure
- Muscle, Skeletal/metabolism
- Myocardium/metabolism
- Myocytes, Cardiac/cytology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Oxidative Phosphorylation/drug effects
- Reactive Oxygen Species/metabolism
- Reperfusion Injury/metabolism
- Reperfusion Injury/pathology
- Tetrazoles/pharmacology
- Thiourea/analogs & derivatives
- Thiourea/pharmacology
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Affiliation(s)
- Ewa Soltysinska
- The Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bo Hjorth Bentzen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
| | - Maria Barthmes
- Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität, Munich, Germany; Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität, Munich, Germany
- Nanion Technologies GmbH, Munich, Germany
| | - Helle Hattel
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - A. Brianne Thrush
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Canada
| | - Mary-Ellen Harper
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Canada
| | - Klaus Qvortrup
- Department of Biomedical Sciences, Core Facility for Integrated Microscopy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Filip J. Larsen
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Tomas A. Schiffer
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Jose Losa-Reyna
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Julia Straubinger
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Angelina Kniess
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Morten Bækgaard Thomsen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Stefanie Fenske
- Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität, Munich, Germany; Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität, Munich, Germany
| | - Martin Biel
- Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität, Munich, Germany; Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität, Munich, Germany
| | - Peter Ruth
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Christian Wahl-Schott
- Center for Integrated Protein Science Munich (CIPSM), Ludwig-Maximilians-Universität, Munich, Germany; Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-Universität, Munich, Germany
| | - Robert Christopher Boushel
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Søren-Peter Olesen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- * E-mail: (SPO); (RL)
| | - Robert Lukowski
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
- * E-mail: (SPO); (RL)
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34
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Skibsbye L, Poulet C, Diness JG, Bentzen BH, Yuan L, Kappert U, Matschke K, Wettwer E, Ravens U, Grunnet M, Christ T, Jespersen T. Small-conductance calcium-activated potassium (SK) channels contribute to action potential repolarization in human atria. Cardiovasc Res 2014; 103:156-67. [PMID: 24817686 DOI: 10.1093/cvr/cvu121] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
AIMS Small-conductance calcium-activated potassium (SK) channels are expressed in the heart of various species, including humans. The aim of the present study was to address whether SK channels play a functional role in human atria. METHODS AND RESULTS Quantitative real-time PCR analyses showed higher transcript levels of SK2 and SK3 than that of the SK1 subtype in human atrial tissue. SK2 and SK3 were reduced in chronic atrial fibrillation (AF) compared with sinus rhythm (SR) patients. Immunohistochemistry using confocal microscopy revealed widespread expression of SK2 in atrial myocytes. Two SK channel inhibitors (NS8593 and ICAGEN) were tested in heterologous expression systems revealing ICAGEN as being highly selective for SK channels, while NS8593 showed less selectivity for these channels. In isolated atrial myocytes from SR patients, both inhibitors decreased inwardly rectifying K(+) currents by ∼15% and prolonged action potential duration (APD), but no effect was observed in myocytes from AF patients. In trabeculae muscle strips from right atrial appendages of SR patients, both compounds increased APD and effective refractory period, and depolarized the resting membrane potential, while only NS8593 induced these effects in tissue from AF patients. SK channel inhibition did not alter any electrophysiological parameter in human interventricular septum tissue. CONCLUSIONS SK channels are present in human atria where they participate in repolarization. SK2 and SK3 were down-regulated and had reduced functional importance in chronic AF. As SK current was not found to contribute substantially to the ventricular AP, pharmacological inhibition of SK channels may be a putative atrial-selective target for future antiarrhythmic drug therapy.
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Affiliation(s)
- Lasse Skibsbye
- Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Claire Poulet
- Department of Pharmacology and Toxicology, Medical Faculty, Technical University Dresden, Dresden, Germany
| | - Jonas Goldin Diness
- Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark Acesion Pharma ApS, Ole Maaløes Vej 3, Copenhagen DK-2200, Denmark
| | - Bo Hjorth Bentzen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark Acesion Pharma ApS, Ole Maaløes Vej 3, Copenhagen DK-2200, Denmark
| | - Lei Yuan
- Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Utz Kappert
- Clinic for Cardiac Surgery, Heart Center Dresden, Medical Faculty, Dresden University of Technology, Dresden, Germany
| | - Klaus Matschke
- Clinic for Cardiac Surgery, Heart Center Dresden, Medical Faculty, Dresden University of Technology, Dresden, Germany
| | - Erich Wettwer
- Department of Pharmacology and Toxicology, Medical Faculty, Technical University Dresden, Dresden, Germany
| | - Ursula Ravens
- Department of Pharmacology and Toxicology, Medical Faculty, Technical University Dresden, Dresden, Germany
| | - Morten Grunnet
- Acesion Pharma ApS, Ole Maaløes Vej 3, Copenhagen DK-2200, Denmark
| | - Torsten Christ
- Department of Pharmacology and Toxicology, Medical Faculty, Technical University Dresden, Dresden, Germany Department of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thomas Jespersen
- Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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Bentzen BH, Grunnet M, Hyveled-Nielsen L, Sundgreen C, Lassen JB, Hansen HH. Anti-hypertensive treatment preserves appetite suppression while preventing cardiovascular adverse effects of tesofensine in rats. Obesity (Silver Spring) 2013; 21:985-92. [PMID: 23784901 DOI: 10.1002/oby.20122] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 09/10/2012] [Indexed: 12/30/2022]
Abstract
OBJECTIVE Tesofensine is a novel triple monoamine reuptake inhibitor which is in development for the treatment of obesity. Preclinical and clinical data suggest that appetite suppression is an important mechanism by which tesofensine exerts its robust weight reducing effect. Notably, the strong hypophagic response to tesofensine treatment is demonstrated to be linked to central stimulation of noradrenergic and dopaminergic neurotransmission. The sympathomimetic mode of action of tesofensine may also associate with the elevated heart rate and blood pressure observed in clinical settings, and we therefore sought experimentally to address this issue. DESIGN AND METHODS The anorexigenic and cardiovascular effects of tesofensine were studied simultaneously in telemetrized conscious rats in a combined real-time food intake and cardiovascular telemetry monitoring system. RESULTS Acute administration of tesofensine caused a dose-dependent hypophagic effect as well as increased heart rate and blood pressure. Interestingly, combined treatment with metoprolol (b1 adrenoceptor blocker, 10-20 mg/kg, p.o.) fully prevented the cardiovascular sympathetic effects of tesofensine while leaving the robust inhibitory efficacy on food intake unaffected. Similarly, the angiotensin AT1 receptor antagonist telmisartan (1.0-3.0 mg/kg, p.o.) did not interfere with the anti-obesity effects of tesofensine, however, telmisartan only partially reversed the increase in systolic blood pressure and had no effect on the elevated heart rate induced by tesofensine. CONCLUSION These data suggests that tesofensine causes elevations in heart rate and blood pressure by increasing sympathetic activity, and that different adrenoceptor subtypes may be responsible for the anti-obesity and cardiovascular effects of tesofensine.
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Abstract
BACKGROUND AND PURPOSE K(v)11.1 channels are involved in regulating cellular excitability in various tissues including brain, heart and smooth muscle. In these tissues, at least two isoforms, K(v)11.1a and K(v)11.1b, with different kinetics, are expressed. K(v)11.1 activators are potential therapeutic agents, but their effects have only been tested on the K(v)11.1a isoform. In this study, the effects of two different K(v)11.1 activators, NS1643 and RPR260243, were characterized on K(v)11.1a and K(v)11.1b channels. EXPERIMENTAL APPROACH K(v)11.1a and K(v)11.1b channels were expressed in Xenopus laevis oocytes, and currents were measured using two-electrode voltage clamp. I/V curves and channel kinetics were measured before and after application of 30 µM NS1643 or 10 µM RPR260243. KEY RESULTS NS1643 increased steady-state currents through Kv11.1b several fold more than through K(v)11.1a channels, without affecting EC(50) values. NS1643 increased activation rates and decreased rates of inactivation, recovery from inactivation and deactivation for both channels. Except for activation, where effect of NS1643 was comparable, relative changes were greater for Kv11.1b than for K(v)11.1a. RPR260243 increased steady-state currents only through Kv11.1a channels, but slowed the process of deactivation for both channels primarily by decreasing time constant of slow deactivation. This effect was greater on K(v)11.1b than on K(v)11.1a. Effects of both compounds on heteromeric K(v)11.1a/K(v)11.1b channels were similar to those on K(v)11.1a. CONCLUSIONS AND IMPLICATIONS Both NS1643 and RPR260243 displayed differential effects on K(v)11.1a and K(v)11.1b channels, the effects being relatively more pronounced on K(v)11.1b channels. This affirms the importance of testing the effect of K(v)11.1 activators on different channel isoforms.
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Affiliation(s)
- A P Larsen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia, Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, Copenhagen N, Denmark
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Andersen AD, Bentzen BH, Salling H, Klingberg H, Kanneworff M, Grunnet M, Pedersen SF. The Cardioprotective Effect of Brief Acidic Reperfusion after Ischemia in Perfused Rat Hearts is not Mimicked by Inhibition of the Na +/H + Exchanger NHE1. Cell Physiol Biochem 2011; 28:13-24. [DOI: 10.1159/000331709] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/16/2011] [Indexed: 01/09/2023] Open
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Osadchii OE, Bentzen BH, Olesen SP. Chamber-specific effects of hypokalaemia on ventricular arrhythmogenicity in isolated, perfused guinea-pig heart. Exp Physiol 2009; 94:434-46. [DOI: 10.1113/expphysiol.2008.045567] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Bentzen BH, Nardi A, Calloe K, Madsen LS, Olesen SP, Grunnet M. The small molecule NS11021 is a potent and specific activator of Ca2+-activated big-conductance K+ channels. Mol Pharmacol 2007; 72:1033-44. [PMID: 17636045 DOI: 10.1124/mol.107.038331] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Large-conductance Ca(2+)- and voltage-activated K(+) channels (Kca1.1/BK/MaxiK) are widely expressed ion channels. They provide a Ca(2+)-dependent feedback mechanism for the regulation of various body functions such as blood flow, neurotransmitter release, uresis, and immunity. In addition, a mitochondrial K(+) channel with KCa1.1-resembling properties has been found in the heart, where it may be involved in regulation of energy consumption. In the present study, the effect of a novel NeuroSearch compound, 1-(3,5-bis-trifluoromethyl-phenyl)-3-[4-bromo-2-(1H-tetrazol-5-yl)-phenyl]-thiourea (NS11021), was investigated on cloned KCa1.1 expressed in Xenopus laevis oocytes and mammalian cells using electrophysiological methods. NS11021 at concentrations above 0.3 microM activated KCa1.1 in a concentration-dependent manner by parallel-shifting the channel activation curves to more negative potentials. Single-channel analysis revealed that NS11021 increased the open probability of the channel by altering gating kinetics without affecting the single-channel conductance. NS11021 (10 microM) influenced neither a number of cloned Kv channels nor endogenous Na(+) and Ca(2+) channels (L- and T-type) in guinea pig cardiac myocytes. In conclusion, NS11021 is a novel KCa1.1 channel activator with better specificity and a 10 times higher potency compared with the most broadly applied KCa1.1 opener, NS1619. Thus, NS11021 might be a valuable tool compound when addressing the physiological and pathophysiological roles of KCa1.1 channels.
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Bentzen BH, Schmitt N, Calloe K, Dalby Brown W, Grunnet M, Olesen SP. The acrylamide (S)-1 differentially affects Kv7 (KCNQ) potassium channels. Neuropharmacology 2006; 51:1068-77. [PMID: 16904708 DOI: 10.1016/j.neuropharm.2006.07.001] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Revised: 04/11/2006] [Accepted: 07/02/2006] [Indexed: 01/11/2023]
Abstract
The family of Kv7 (KCNQ) potassium channels consists of five members. Kv7.2 and 3 are the primary molecular correlates of the M-current, but also Kv7.4 and Kv7.5 display M-current characteristics. M-channel modulators include blockers (e.g., linopirdine) for cognition enhancement and openers (e.g., retigabine) for treatment of epilepsy and neuropathic pain. We investigated the effect of a Bristol-Myers Squibb compound (S)-N-[1-(3-morpholin-4-yl-phenyl)-ethyl]-3-phenyl-acrylamide [(S)-1] on cloned human Kv7.1-5 potassium channels expressed in Xenopus laevis oocytes. Using two-electrode voltage-clamp recordings we found that (S)-1 blocks Kv7.1 and Kv7.1/KCNE1 currents. In contrast, (S)-1 produced a hyperpolarizing shift of the activation curve for Kv7.2, Kv7.2/Kv7.3, Kv7.4 and Kv7.5. Further, the compound enhanced the maximal current amplitude at all potentials for Kv7.4 and Kv7.5 whereas the combined activation/block of Kv7.2 and Kv7.2/3 was strongly voltage-dependent. The tryptophan residue 242 in S5, known to be crucial for the effect of retigabine, was also shown to be critical for the enhancing effect of (S)-1 and BMS204352. Furthermore, no additive effect on Kv7.4 current amplitude was observed when both retigabine and (S)-1 or BMS204352 were applied simultaneously. In conclusion, (S)-1 differentially affects the Kv7 channel subtypes and is dependent on a single tryptophan for the current enhancing effect in Kv7.4.
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Affiliation(s)
- Bo Hjorth Bentzen
- The Danish National Research Foundation Centre for Cardiac Arrhythmia and Department of Medical Physiology, The Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
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Grauballe MCB, Bentzen BH, Björnsson M, Moe D, Jonassen TEN, Bendtzen K, Stoltze K, Holmstrup P. The effect of spironolactone on experimental periodontitis in rats. J Periodontal Res 2005; 40:212-7. [PMID: 15853966 DOI: 10.1111/j.1600-0765.2005.00792.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Elevated levels of tumour necrosis factor (TNF) have been found in patients with adult periodontitis. Animal studies have shown that TNF plays an important role in the pathogenesis of periodontitis. New findings suggest that the aldosterone-inhibitor spironolactone possesses an anti-TNF effect. The purpose of the study was to determine the anti-TNF effect of spironolactone in an endotoxic shock rat model and to disclose the effect of oral administration of spironolactone on the development of experimental periodontitis in rats. METHODS The study was divided in two parts. Part 1: oral administration of spironolactone (100 mg/kg) followed by intravenous lipopolysaccharide (1 mg/kg) infusion 45 min later. Blood samples were taken before and 90 min after lipopolysaccharide infusion to determine the TNF levels in spironolactone treated and non-treated rats. Part 2: oral administration of spironolactone [100 mg/(kg day)] starting 2 days prior to induction of experimental periodontitis established by peridental ligatures. Morphometrical and radiographical registrations of alveolar bone destruction were carried out to determine the effect of spironolactone on the progression of experimental periodontitis. RESULTS In part 1 the endotoxic shock model showed a significant reduction in TNF levels in the spironolactone-treated group compared to the non-treated group, suggesting that spironolactone acts as a TNF inhibitor. In part 2 spironolactone-treated rats did not demonstrate significantly less alveolar bone destruction compared to non-treated rats. CONCLUSIONS The insignificant effect of spironolactone treatment could be explained by the fast metabolism of spironolactone and that spironolactone does not completely inhibit TNF production in rats. Moreover, many other cytokines and mediators involved in alveolar bone destruction may account for the lacking response to spironolactone.
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Affiliation(s)
- M C B Grauballe
- Department of Periodontology, School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
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