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Kaneko N, Loughrey CM, Smith G, Matsuda R, Hasunuma T, Mark PB, Toda M, Shinozaki M, Otani N, Kayley S, Da Silva Costa A, Martin TP, Dobi S, Saxena P, Shimamoto K, Ishikawa T, Kambayashi R, Riddell A, Elliott EB, McCarroll CS, Sakai T, Mitsuhisa Y, Hirano S, Kitai T, Kusano K, Inoue Y, Nakamura M, Kikuchi M, Toyoda S, Taguchi I, Fujiwara T, Sugiyama A, Kumagai Y, Iwata K. A novel ryanodine receptor 2 inhibitor, M201-A, enhances natriuresis, renal function and lusi-inotropic actions: Preclinical and phase I study. Br J Pharmacol 2024; 181:3401-3419. [PMID: 38773354 DOI: 10.1111/bph.16379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 02/17/2024] [Accepted: 02/20/2024] [Indexed: 05/23/2024] Open
Abstract
BACKGROUND AND PURPOSE The ryanodine receptor 2 (RyR2) is present in both the heart and kidneys, and plays a crucial role in maintaining intracellular Ca2+ homeostasis in cells in these organs. This study aimed to investigate the impact of M201-A on RyR2, as well as studying its effects on cardiac and renal functions in preclinical and clinical studies. EXPERIMENTAL APPROACH Following the administration of M201-A (1,4-benzothiazepine-1-oxide derivative), we monitored diastolic Ca2+ leak via RyR2 and intracellular Ca2+ concentration in isolated rat cardiomyocytes and in cardiac and renal function in animals. In a clinical study, M201-A was administered intravenously at doses of 0.2 and 0.4 mg·kg-1 once daily for 20 min for four consecutive days in healthy males, with the assessment of haemodynamic responses. KEY RESULTS In rat heart cells, M201-A effectively inhibited spontaneous diastolic Ca2+ leakage through RyR2 and exhibited positive lusi-inotropic effects on the rat heart. Additionally, it enhanced natriuresis and improved renal function in dogs. In human clinical studies, when administered intravenously, M201-A demonstrated an increase in natriuresis, glomerular filtration rate and creatinine clearance, while maintaining acceptable levels of drug safety and tolerability. CONCLUSIONS AND IMPLICATIONS The novel drug M201-A inhibited diastolic Ca2+ leak via RyR2, improved cardiac lusi-inotropic effects in rats, and enhanced natriuresis and renal function in humans. These findings suggest that this drug may offer a potential new treatment option for chronic kidney disease and heart failure.
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Affiliation(s)
- Noboru Kaneko
- Department of Medicine, Dokkyo Medical University, Tochigi, Japan
- AETAS Pharma Co., Ltd., Tokyo, Japan
| | | | - Godfrey Smith
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK
| | - Ryuko Matsuda
- AETAS Pharma Co., Ltd., Tokyo, Japan
- Nojima Hospital, Tottori, Japan
| | | | - Patric B Mark
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK
| | | | | | - Naoyuki Otani
- Dokkyo Medical University Nikko Medical Center, Tochigi, Japan
| | - Scott Kayley
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK
| | - Ana Da Silva Costa
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK
| | - Tamara P Martin
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK
| | - Sara Dobi
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK
| | - Priyanka Saxena
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK
| | - Ken Shimamoto
- Division of Cardiovascular Medicine, Sendai Cardiovascular Center, Miyagi, Japan
| | - Tetsuya Ishikawa
- Department of Cardiology, Dokkyo Medical University, Saitama Medical Center, Saitama, Japan
| | - Ryuichi Kambayashi
- Department of Pharmacology, Faculty of Medicine, Toho University, Tokyo, Japan
| | - Alexandra Riddell
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK
| | - Elspeth B Elliott
- School of Cardiovascular and Metabolic Health, University of Glasgow, Glasgow, UK
| | | | | | | | - Sayuri Hirano
- Process Research & Development Laboratories Technology Research & Development Division, Sumitomo Dainippon Pharma Co. Ltd., Osaka, Japan
| | - Takeshi Kitai
- Department of Heart Failure and Transplantation, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Kengo Kusano
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Osaka, Japan
| | - Yuko Inoue
- Department of Heart Failure and Transplantation, National Cerebral and Cardiovascular Center, Osaka, Japan
| | | | - Migaku Kikuchi
- Department of Cardiovascular Medicine, Dokkyo Medical University, Tochigi, Japan
| | - Shigeru Toyoda
- Department of Cardiovascular Medicine, Dokkyo Medical University, Tochigi, Japan
| | - Isao Taguchi
- Department of Cardiology, Dokkyo Medical University, Saitama Medical Center, Saitama, Japan
| | | | - Atsushi Sugiyama
- Department of Pharmacology, Faculty of Medicine, Toho University, Tokyo, Japan
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Kistamás K, Veress R, Horváth B, Bányász T, Nánási PP, Eisner DA. Calcium Handling Defects and Cardiac Arrhythmia Syndromes. Front Pharmacol 2020; 11:72. [PMID: 32161540 PMCID: PMC7052815 DOI: 10.3389/fphar.2020.00072] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/24/2020] [Indexed: 12/13/2022] Open
Abstract
Calcium ions (Ca2+) play a major role in the cardiac excitation-contraction coupling. Intracellular Ca2+ concentration increases during systole and falls in diastole thereby determining cardiac contraction and relaxation. Normal cardiac function also requires perfect organization of the ion currents at the cellular level to drive action potentials and to maintain action potential propagation and electrical homogeneity at the tissue level. Any imbalance in Ca2+ homeostasis of a cardiac myocyte can lead to electrical disturbances. This review aims to discuss cardiac physiology and pathophysiology from the elementary membrane processes that can cause the electrical instability of the ventricular myocytes through intracellular Ca2+ handling maladies to inherited and acquired arrhythmias. Finally, the paper will discuss the current therapeutic approaches targeting cardiac arrhythmias.
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Affiliation(s)
- Kornél Kistamás
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Division of Cardiovascular Sciences, School of Medical Sciences, University of Manchester, Manchester, United Kingdom
| | - Roland Veress
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Balázs Horváth
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Tamás Bányász
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Péter P Nánási
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary.,Department of Dental Physiology, Faculty of Dentistry, University of Debrecen, Debrecen, Hungary
| | - David A Eisner
- Division of Cardiovascular Sciences, School of Medical Sciences, University of Manchester, Manchester, United Kingdom
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3
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Connell P, Word TA, Wehrens XHT. Targeting pathological leak of ryanodine receptors: preclinical progress and the potential impact on treatments for cardiac arrhythmias and heart failure. Expert Opin Ther Targets 2020; 24:25-36. [PMID: 31869254 DOI: 10.1080/14728222.2020.1708326] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Introduction: Type-2 ryanodine receptor (RyR2) located on the sarcoplasmic reticulum initiate systolic Ca2+ transients within cardiomyocytes. Proper functioning of RyR2 is therefore crucial to the timing and force generated by cardiomyocytes within a healthy heart. Improper intracellular Ca2+ handing secondary to RyR2 dysfunction is associated with a variety of cardiac pathologies including catecholaminergic polymorphic ventricular tachycardia (CPVT), atrial fibrillation (AF), and heart failure (HF). Thus, RyR2 and its associated accessory proteins provide promising drug targets to scientists developing therapeutics for a variety of cardiac pathologies.Areas covered: In this article, we review the role of RyR2 in a variety of cardiac pathologies. We performed a literature search utilizing PubMed and MEDLINE as well as reviewed registries of trials from clinicaltrials.gov from 2010 to 2019 for novel therapeutic approaches that address the cellular mechanisms underlying CPVT, AF, and HF by specifically targeting defective RyR2 channels.Expert opinion: The negative impact of cardiac dysfunction on human health and medical economics are major motivating factors for establishing new and effective therapeutic approaches. Focusing on directly impacting the molecular mechanisms underlying defective Ca2+ handling by RyR2 in HF and arrhythmia has great potential to be translated into novel and innovative therapies.
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Affiliation(s)
- Patrick Connell
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA.,Departments of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Tarah A Word
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA.,Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA.,Departments of Pediatrics, Baylor College of Medicine, Houston, TX, USA.,Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX, USA.,Medicine (Cardiology, Baylor College of Medicine, Houston, TX, USA.,Neuroscience, Baylor College of Medicine, Houston, TX, USA.,Center for Space Medicine, Baylor College of Medicine, Houston, TX, USA
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4
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Mohamed BA, Hartmann N, Tirilomis P, Sekeres K, Li W, Neef S, Richter C, Zeisberg EM, Kattner L, Didié M, Guan K, Schmitto JD, Lehnart SE, Luther S, Voigt N, Seidler T, Sossalla S, Hasenfuss G, Toischer K. Sarcoplasmic reticulum calcium leak contributes to arrhythmia but not to heart failure progression. Sci Transl Med 2018; 10:10/458/eaan0724. [DOI: 10.1126/scitranslmed.aan0724] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 01/30/2018] [Accepted: 08/09/2018] [Indexed: 12/30/2022]
Abstract
Increased sarcoplasmic reticulum (SR) Ca2+ leak via the cardiac ryanodine receptor (RyR2) has been suggested to play a mechanistic role in the development of heart failure (HF) and cardiac arrhythmia. Mice treated with a selective RyR2 stabilizer, rycal S36, showed normalization of SR Ca2+ leak and improved survival in pressure overload (PO) and myocardial infarction (MI) models. The development of HF, measured by echocardiography and molecular markers, showed no difference in rycal S36– versus placebo-treated mice. Reduction of SR Ca2+ leak in the PO model by the rycal-unrelated RyR2 stabilizer dantrolene did not mitigate HF progression. Development of HF was not aggravated by increased SR Ca2+ leak due to RyR2 mutation (R2474S) in volume overload, an SR Ca2+ leak–independent HF model. Arrhythmia episodes were reduced by rycal S36 treatment in PO and MI mice in vivo and ex vivo in Langendorff-perfused hearts. Isolated cardiomyocytes from murine failing hearts and human ventricular failing and atrial nonfailing myocardium showed reductions in delayed afterdepolarizations, in spontaneous and induced Ca2+ waves, and in triggered activity in rycal S36 versus placebo cells, whereas the Ca2+ transient, SR Ca2+ load, SR Ca2+ adenosine triphosphatase function, and action potential duration were not affected. Rycal S36 treatment of human induced pluripotent stem cells isolated from a patient with catecholaminergic polymorphic ventricular tachycardia could rescue the leaky RyR2 receptor. These results suggest that SR Ca2+ leak does not primarily influence contractile HF progression, whereas rycal S36 treatment markedly reduces ventricular arrhythmias, thereby improving survival in mice.
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Affiliation(s)
- Belal A. Mohamed
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
- Department of Medical Biochemistry and Molecular Biology, Faculty of Medicine, Mansoura University, Mansoura City 35516, Egypt
| | - Nico Hartmann
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
| | - Petros Tirilomis
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
| | - Karolina Sekeres
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- Institute of Pharmacology and Toxicology, Technische Universität Dresden, 01307 Dresden, Germany
| | - Wener Li
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- Institute of Pharmacology and Toxicology, Technische Universität Dresden, 01307 Dresden, Germany
| | - Stefan Neef
- Department of Internal Medicine II, University Hospital Regensburg, 93053 Regensburg, Germany
| | - Claudia Richter
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
| | - Elisabeth M. Zeisberg
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
| | - Lars Kattner
- Endotherm Life Science Molecules, 66123 Saarbrücken, Germany
| | - Michael Didié
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
- Institute of Pharmacology and Toxicology, Georg-August-University, 37075 Göttingen, Germany
| | - Kaomei Guan
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- Institute of Pharmacology and Toxicology, Technische Universität Dresden, 01307 Dresden, Germany
| | - Jan D. Schmitto
- Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, 30625 Hannover, Germany
| | - Stephan E. Lehnart
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
- BioMET, Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Stefan Luther
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
- Research Group Biomedical Physics, Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
- Institute of Pharmacology and Toxicology, Georg-August-University, 37075 Göttingen, Germany
| | - Niels Voigt
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
- Institute of Pharmacology and Toxicology, Georg-August-University, 37075 Göttingen, Germany
| | - Tim Seidler
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
| | - Samuel Sossalla
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
- Department of Internal Medicine II, University Hospital Regensburg, 93053 Regensburg, Germany
| | - Gerd Hasenfuss
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
| | - Karl Toischer
- Department of Cardiology and Pneumology, Georg-August-University, 37075 Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, 37075 Göttingen, Germany
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Abstract
For arrhythmia triggers that are secondary to dysfunctional intracellular Ca2+ cycling, there are few, if any, agents that specifically target the Ca2+ handling machinery. However, several candidates have been proposed in the literature. Here we review the idea that these agents or their derivatives will prove invaluable in clinical applications in the future.
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Affiliation(s)
- Penelope A Boyden
- Department of Pharmacology, Center for Molecular Therapeutics, Columbia University, New York, New York.
| | - Godfrey L Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, United Kingdom
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6
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Dobrev D, Wehrens XHT. Calcium-mediated cellular triggered activity in atrial fibrillation. J Physiol 2017; 595:4001-4008. [PMID: 28181690 DOI: 10.1113/jp273048] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 01/25/2017] [Indexed: 12/29/2022] Open
Abstract
Although atrial fibrillation (AF) is the most commonly encountered cardiac arrhythmia, the basic mechanisms underlying this disorder remain incompletely understood. During the past decade or so, it has become clear that alterations in intracellular Ca2+ handling may play a role in the pathogenesis of AF. Studies in small and large animal models, as well as atrial samples from patients with different forms of AF, have implicated ryanodine receptor type 2 (RyR2) dysfunction and enhanced spontaneous Ca2+ release events from the sarcoplasmic reticulum (SR) as a potential cause of proarrhythmic cellular ectopic (triggered) activity in AF. The molecular mechanisms leading to RyR2 dysfunction and SR Ca2+ leak depend on the clinical stage of AF or specific animal model studied. This review focuses on the mechanisms and role of calcium-mediated cellular triggered activity in AF, and addresses some of the current controversies in the field.
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Affiliation(s)
- Dobromir Dobrev
- Institute for Pharmacology, West German Heart and Vascular Centre, University Duisburg-Essen, Essen, Germany.,Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Baylor College of Medicine, Houston, TX, USA.,Departments of Molecular Physiology & Biophysics, Pediatrics (Cardiology), Medicine (Cardiology), Baylor College of Medicine, Houston, TX, USA
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del Canto I, Such-Miquel L, Brines L, Soler C, Zarzoso M, Calvo C, Parra G, Tormos Á, Alberola A, Millet J, Such L, Chorro FJ. Effects of JTV-519 on stretch-induced manifestations of mechanoelectric feedback. Clin Exp Pharmacol Physiol 2016; 43:1062-1070. [DOI: 10.1111/1440-1681.12630] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2016] [Revised: 07/16/2016] [Accepted: 08/01/2016] [Indexed: 12/29/2022]
Affiliation(s)
- Irene del Canto
- Department of Medicine; Valencia University “Estudi General”; Valencia Spain
| | - Luis Such-Miquel
- Department of Physiotherapy; Valencia University “Estudi General”; Valencia Spain
| | - Laia Brines
- Department of Physiology; Valencia University “Estudi General”; Valencia Spain
| | - Carlos Soler
- Department of Physiology; Valencia University “Estudi General”; Valencia Spain
| | - Manuel Zarzoso
- Department of Physiotherapy; Valencia University “Estudi General”; Valencia Spain
| | - Conrado Calvo
- Department of Electronic Engineering; Valencia Polytechnic University; Valencia Spain
| | - Germán Parra
- Department of Physiology; Valencia University “Estudi General”; Valencia Spain
| | - Álvaro Tormos
- Department of Electronic Engineering; Valencia Polytechnic University; Valencia Spain
| | - Antonio Alberola
- Department of Physiology; Valencia University “Estudi General”; Valencia Spain
| | - José Millet
- Department of Electronic Engineering; Valencia Polytechnic University; Valencia Spain
| | - Luis Such
- Department of Physiology; Valencia University “Estudi General”; Valencia Spain
| | - Francisco J. Chorro
- Department of Medicine; Valencia University “Estudi General”; Valencia Spain
- Department of Cardiology; Valencia University Clinic Hospital; INCLIVA; Valencia Spain
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8
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Abstract
Calcium/calmodulin-dependent protein kinase II (CaMKII) has emerged as key enzyme in many cardiac pathologies, especially heart failure (HF), myocardial infarction and cardiomyopathies, thus leading to contractile dysfunction and malignant arrhythmias. While many pathways leading to CaMKII activation have been elucidated in recent years, hardly any clinically viable compounds affecting CaMKII activity have progressed from basic in vitro science to in vivo studies. This review focuses on recent advances in anti-arrhythmic strategies involving CaMKII. Specifically, both inhibition of CaMKII itself to prevent arrhythmias, as well as anti-arrhythmic approaches affecting CaMKII activity via alterations in signaling cascades upstream and downstream of CaMKII will be discussed.
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Affiliation(s)
- Julian Mustroph
- Universitäres Herzzentrum Regensburg, Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Germany
| | - Stefan Neef
- Universitäres Herzzentrum Regensburg, Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Germany
| | - Lars S Maier
- Universitäres Herzzentrum Regensburg, Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, Germany.
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9
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Darcy YL, Diaz-Sylvester PL, Copello JA. K201 (JTV519) is a Ca2+-Dependent Blocker of SERCA and a Partial Agonist of Ryanodine Receptors in Striated Muscle. Mol Pharmacol 2016; 90:106-15. [PMID: 27235390 DOI: 10.1124/mol.115.102277] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 05/26/2016] [Indexed: 12/26/2022] Open
Abstract
K201 (JTV-519) may prevent abnormal Ca(2+) leak from the sarcoplasmic reticulum (SR) in the ischemic heart and skeletal muscle (SkM) by stabilizing the ryanodine receptors (RyRs; RyR1 and RyR2, respectively). We tested direct modulation of the SR Ca(2+)-stimulated ATPase (SERCA) and RyRs by K201. In isolated cardiac and SkM SR microsomes, K201 slowed the rate of SR Ca(2+) loading, suggesting potential SERCA block and/or RyR agonism. K201 displayed Ca(2+)-dependent inhibition of SERCA-dependent ATPase activity, which was measured in microsomes incubated with 200, 2, and 0.25 µM Ca(2+) and with the half-maximal K201 inhibitory doses (IC50) estimated at 130, 19, and 9 µM (cardiac muscle) and 104, 13, and 5 µM (SkM SR). K201 (≥5 µM) increased RyR1-mediated Ca(2+) release from SkM microsomes. Maximal K201 doses at 80 µM produced ∼37% of the increase in SkM SR Ca(2+) release observed with the RyR agonist caffeine. K201 (≥5 µM) increased the open probability (Po) of very active ("high-activity") RyR1 of SkM reconstituted into bilayers, but it had no effect on "low-activity" channels. Likewise, K201 activated cardiac RyR2 under systolic Ca(2+) conditions (∼5 µM; channels at Po ∼0.3) but not under diastolic Ca(2+) conditions (∼100 nM; Po < 0.01). Thus, K201-induced the inhibition of SR Ca(2+) leak found in cell-system studies may relate to potentially potent SERCA block under resting Ca(2+) conditions. SERCA block likely produces mild SR depletion in normal conditions but could prevent SR Ca(2+) overload under pathologic conditions, thus precluding abnormal RyR-mediated Ca(2+) release.
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Affiliation(s)
- Yuanzhao L Darcy
- Department of Pharmacology (Y.L.D., P.L.D.-S., J.A.C.) and Center for Clinical Research (P.L.D.-S.), Southern Illinois University School of Medicine, Springfield, Illinois
| | - Paula L Diaz-Sylvester
- Department of Pharmacology (Y.L.D., P.L.D.-S., J.A.C.) and Center for Clinical Research (P.L.D.-S.), Southern Illinois University School of Medicine, Springfield, Illinois
| | - Julio A Copello
- Department of Pharmacology (Y.L.D., P.L.D.-S., J.A.C.) and Center for Clinical Research (P.L.D.-S.), Southern Illinois University School of Medicine, Springfield, Illinois
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Kim JJ, Němec J, Li Q, Salama G. Synchronous systolic subcellular Ca2+-elevations underlie ventricular arrhythmia in drug-induced long QT type 2. Circ Arrhythm Electrophysiol 2015; 8:703-12. [PMID: 25722252 PMCID: PMC4472565 DOI: 10.1161/circep.114.002214] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 02/11/2015] [Indexed: 12/19/2022]
Abstract
BACKGROUND Repolarization delay is a common clinical problem, which can promote ventricular arrhythmias. In myocytes, abnormal sarcoplasmic reticulum Ca(2+)-release is proposed as the mechanism that causes early afterdepolarizations, the cellular equivalent of ectopic-activity in drug-induced long-QT syndrome. A crucial missing link is how such a stochastic process can overcome the source-sink mismatch to depolarize sufficient ventricular tissue to initiate arrhythmias. METHODS AND RESULTS Optical maps of action potentials and Ca(2+)-transients from Langendorff rabbit hearts were measured at low (150×150 μm(2)/pixel) and high (1.5×1.5 μm(2)/pixel) resolution before and during arrhythmias. Drug-induced long QT type 2, elicited with dofetilide inhibition of IKr (the rapid component of rectifying K+ current), produced spontaneous Ca(2+)-elevations during diastole and systole, before the onset of arrhythmias. Diastolic Ca(2+-)waves appeared randomly, propagated within individual myocytes, were out-of-phase with adjacent myocytes, and often died-out. Systolic secondary Ca(2+-)elevations were synchronous within individual myocytes, appeared 188±30 ms after the action potential-upstroke, occurred during high cytosolic Ca(2+) (40%-60% of peak-Ca(2+)-transients), appeared first in small islands (0.5×0.5 mm(2)) that enlarged and spread throughout the epicardium. Synchronous systolic Ca(2+-)elevations preceded voltage-depolarizations (9.2±5 ms; n=5) and produced pronounced Spatial Heterogeneities of Ca(2+)-transient-durations and action potential-durations. Early afterdepolarizations originating from sites with the steepest gradients of membrane-potential propagated and initiated arrhythmias. Interestingly, more complex subcellular Ca(2+)-dynamics (multiple chaotic Ca(2+)-waves) occurred during arrhythmias. K201, a ryanodine receptor stabilizer, eliminated Ca(2+)-elevations and arrhythmias. CONCLUSIONS The results indicate that systolic and diastolic Ca(2+)-elevations emanate from sarcoplasmic reticulum Ca(2+)-release and systolic Ca(2+)-elevations are synchronous because of high cytosolic and luminal-sarcoplasmic reticulum Ca(2+), which overcomes source-sink mismatch to trigger arrhythmias in intact hearts.
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Affiliation(s)
- Jong J Kim
- From the Department of Bioengineering (J.J.K., G.S.), and Department of Medicine, Heart and Vascular Institute (J.J.K., J.N., Q.L., G.S.), University of Pittsburgh, PA; and Tsinghua University School of Medicine, China (Q.L)
| | - Jan Němec
- From the Department of Bioengineering (J.J.K., G.S.), and Department of Medicine, Heart and Vascular Institute (J.J.K., J.N., Q.L., G.S.), University of Pittsburgh, PA; and Tsinghua University School of Medicine, China (Q.L)
| | - Qiao Li
- From the Department of Bioengineering (J.J.K., G.S.), and Department of Medicine, Heart and Vascular Institute (J.J.K., J.N., Q.L., G.S.), University of Pittsburgh, PA; and Tsinghua University School of Medicine, China (Q.L)
| | - Guy Salama
- From the Department of Bioengineering (J.J.K., G.S.), and Department of Medicine, Heart and Vascular Institute (J.J.K., J.N., Q.L., G.S.), University of Pittsburgh, PA; and Tsinghua University School of Medicine, China (Q.L).
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11
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Kim JJ, Yang L, Lin B, Zhu X, Sun B, Kaplan AD, Bett GCL, Rasmusson RL, London B, Salama G. Mechanism of automaticity in cardiomyocytes derived from human induced pluripotent stem cells. J Mol Cell Cardiol 2015; 81:81-93. [PMID: 25644533 PMCID: PMC4409767 DOI: 10.1016/j.yjmcc.2015.01.013] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 11/26/2014] [Accepted: 01/15/2015] [Indexed: 10/24/2022]
Abstract
BACKGROUND AND OBJECTIVES The creation of cardiomyocytes derived from human induced pluripotent stem cells (hiPS-CMs) has spawned broad excitement borne out of the prospects to diagnose and treat cardiovascular diseases based on personalized medicine. A common feature of hiPS-CMs is their spontaneous contractions but the mechanism(s) remain uncertain. METHODS Intrinsic activity was investigated by the voltage-clamp technique, optical mapping of action potentials (APs) and intracellular Ca(2+) (Cai) transients (CaiT) at subcellular-resolution and pharmacological interventions. RESULTS The frequency of spontaneous CaiT (sCaiT) in monolayers of hiPS-CMs was not altered by ivabradine, an inhibitor of the pacemaker current, If despite high levels of HCN transcripts (1-4). HiPS-CMs had negligible If and IK1 (inwardly-rectifying K(+)-current) and a minimum diastolic potential of -59.1±3.3mV (n=18). APs upstrokes were preceded by a depolarizing-foot coincident with a rise of Cai. Subcellular Cai wavelets varied in amplitude, propagated and died-off; larger Cai-waves triggered cellular sCaTs and APs. SCaiTs increased in frequency with [Ca(2+)]out (0.05-to-1.8mM), isoproterenol (1μM) or caffeine (100μM) (n≥5, p<0.05). HiPS-CMs became quiescent with ryanodine receptor stabilizers (K201=2μM); tetracaine; Na-Ca exchange (NCX) inhibition (SEA0400=2μM); higher [K(+)]out (5→8mM), and thiol-reducing agents but could still be electrically stimulated to elicit CaiTs. Cell-cell coupling of hiPS-CM in monolayers was evident from connexin-43 expression and CaiT propagation. SCaiTs from an ensemble of dispersed hiPS-CMs were out-of-phase but became synchronous through the outgrowth of inter-connecting microtubules. CONCLUSIONS Automaticity in hiPS-CMs originates from a Ca(2+)-clock mechanism involving Ca(2+) cycling across the sarcoplasmic reticulum linked to NCX to trigger APs.
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Affiliation(s)
- Jong J Kim
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA; Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Lei Yang
- Department of Developmental Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Bo Lin
- Department of Developmental Biology, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Xiaodong Zhu
- University of Iowa, Carver College of Medicine, Division of Cardiovascular Medicine, Iowa City, IA 52242, USA
| | - Bin Sun
- Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Aaron D Kaplan
- Center for Cellular and Systems Electrophysiology, University at Buffalo, State University of New York, Buffalo, NY 14214, USA
| | - Glenna C L Bett
- Center for Cellular and Systems Electrophysiology, University at Buffalo, State University of New York, Buffalo, NY 14214, USA; Departments of Physiology and Biophysics, University at Buffalo, State University of New York, Buffalo, NY 14214, USA; Departments of Gynecology-Obstetrics, University at Buffalo, State University of New York, Buffalo, NY 14214, USA
| | - Randall L Rasmusson
- Center for Cellular and Systems Electrophysiology, University at Buffalo, State University of New York, Buffalo, NY 14214, USA; Departments of Physiology and Biophysics, University at Buffalo, State University of New York, Buffalo, NY 14214, USA
| | - Barry London
- University of Iowa, Carver College of Medicine, Division of Cardiovascular Medicine, Iowa City, IA 52242, USA
| | - Guy Salama
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA; Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15261, USA.
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Ferrantini C, Coppini R, Sacconi L, Tosi B, Zhang ML, Wang GL, de Vries E, Hoppenbrouwers E, Pavone F, Cerbai E, Tesi C, Poggesi C, ter Keurs HEDJ. Impact of detubulation on force and kinetics of cardiac muscle contraction. ACTA ACUST UNITED AC 2014; 143:783-97. [PMID: 24863933 PMCID: PMC4035744 DOI: 10.1085/jgp.201311125] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
T-tubule uncoupling from the plasma membrane leads to myocardial contractile abnormalities. Action potential–driven Ca2+ currents from the transverse tubules (t-tubules) trigger synchronous Ca2+ release from the sarcoplasmic reticulum of cardiomyocytes. Loss of t-tubules has been reported in cardiac diseases, including heart failure, but the effect of uncoupling t-tubules from the sarcolemma on cardiac muscle mechanics remains largely unknown. We dissected intact rat right ventricular trabeculae and compared force, sarcomere length, and intracellular Ca2+ in control trabeculae with trabeculae in which the t-tubules were uncoupled from the plasma membrane by formamide-induced osmotic shock (detubulation). We verified disconnection of a consistent fraction of t-tubules from the sarcolemma by two-photon fluorescence imaging of FM4-64–labeled membranes and by the absence of tubular action potential, which was recorded by random access multiphoton microscopy in combination with a voltage-sensitive dye (Di-4-AN(F)EPPTEA). Detubulation reduced the amplitude and prolonged the duration of Ca2+ transients, leading to slower kinetics of force generation and relaxation and reduced twitch tension (1 Hz, 30°C, 1.5 mM [Ca2+]o). No mechanical changes were observed in rat left atrial trabeculae after formamide shock, consistent with the lack of t-tubules in rodent atrial myocytes. Detubulation diminished the rate-dependent increase of Ca2+-transient amplitude and twitch force. However, maximal twitch tension at high [Ca2+]o or in post-rest potentiated beats was unaffected, although contraction kinetics were slower. The ryanodine receptor (RyR)2 Ca-sensitizing agent caffeine (200 µM), which increases the velocity of transverse Ca2+ release propagation in detubulated cardiomyocytes, rescued the depressed contractile force and the slower twitch kinetics of detubulated trabeculae, with negligible effects in controls. We conclude that partial loss of t-tubules leads to myocardial contractile abnormalities that can be rescued by enhancing and accelerating the propagation of Ca2+-induced Ca2+ release to orphan RyR2 clusters.
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Affiliation(s)
- Cecilia Ferrantini
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy
| | - Raffaele Coppini
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy
| | - Leonardo Sacconi
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy National Institute of Optics, National Research Council, 50019 Sesto Fiorentino, Italy
| | - Benedetta Tosi
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy
| | - Mei Luo Zhang
- Department of Cardiac Sciences of the Libin Institute at the Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Guo Liang Wang
- Department of Cardiac Sciences of the Libin Institute at the Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Ewout de Vries
- Department of Cardiac Sciences of the Libin Institute at the Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Ernst Hoppenbrouwers
- Department of Cardiac Sciences of the Libin Institute at the Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Francesco Pavone
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy National Institute of Optics, National Research Council, 50019 Sesto Fiorentino, Italy
| | - Elisabetta Cerbai
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy
| | - Chiara Tesi
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy
| | - Corrado Poggesi
- Center of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, ItalyCenter of Molecular Medicine, Department of Experimental and Clinical Medicine, Division of Physiology, Department of NeuroFarBa, Division of Pharmacology, LENS, European Laboratory for Non-Linear Spectroscopy, and Department of Physics, University of Florence, 50121 Florence, Italy
| | - Henk E D J ter Keurs
- Department of Cardiac Sciences of the Libin Institute at the Faculty of Medicine, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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Driessen HE, Bourgonje VJA, van Veen TAB, Vos MA. New antiarrhythmic targets to control intracellular calcium handling. Neth Heart J 2014; 22:198-213. [PMID: 24733689 PMCID: PMC4016334 DOI: 10.1007/s12471-014-0549-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Sudden cardiac death due to ventricular arrhythmias is a major problem. Drug therapies to prevent SCD do not provide satisfying results, leading to the demand for new antiarrhythmic strategies. New targets include Ca2+/Calmodulin-dependent protein kinase II (CaMKII), the Na/Ca exchanger (NCX), the Ryanodine receptor (RyR, and its associated protein FKBP12.6 (Calstabin)) and the late component of the sodium current (INa-Late), all related to intracellular calcium (Ca2+) handling. In this review, drugs interfering with these targets (SEA-0400, K201, KN-93, W7, ranolazine, sophocarpine, and GS-967) are evaluated and their future as clinical compounds is considered. These new targets prove to be interesting; however more insight into long-term drug effects is necessary before clinical applicability becomes reality.
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Affiliation(s)
- H E Driessen
- Department of Medical Physiology, Division of Heart & Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM, Utrecht, the Netherlands,
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14
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Breckner A, Ganz M, Marcellin D, Richter J, Gerwin N, Rausch M. Effect of Calstabin1 depletion on calcium transients and energy utilization in muscle fibers and treatment opportunities with RyR1 stabilizers. PLoS One 2013; 8:e81277. [PMID: 24303040 PMCID: PMC3841141 DOI: 10.1371/journal.pone.0081277] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 10/21/2013] [Indexed: 11/29/2022] Open
Abstract
Depletion of calstabin1 (FKBP12) from the RyR1 channel and consequential calcium leakage from the sarcoplasmic reticulum (SR) is found in certain disease conditions such as dystrophy, aging or muscle overuse. Here, we first assessed the effect of calstabin1 depletion on resting Ca2+ levels and transients. We found that depletion of calstabin1 with the calstabin1-dissociation compound FK506 increased the release of calcium from the SR by 14 % during tetanic stimulation (50 Hz, 300 ms) and delayed cytosolic calcium removal. However, we did not find a significant increase in resting cytosolic Ca2+ levels. Therefore, we tested if increased SERCA activity could counterbalance calcium leakage. By measuring the energy utilization of muscle fibers with and without FK506 treatment, we observed that FK506-treatment increased oxygen consumption by 125% compared to baseline levels. Finally, we found that pretreatment of muscle fibers with the RyR1 stabilizer JTV-519 led to an almost complete normalization of calcium flux dynamics and energy utilization. We conclude that cytosolic calcium levels are mostly preserved in conditions with leaky RyR1 channels due to increased SERCA activity. Therefore, we suggest that RyR1 leakiness might lead to chronic metabolic stress, followed by cellular damage, and RyR1 stabilizers could potentially protect diseased muscle tissue.
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Affiliation(s)
- Anke Breckner
- Global Imaging Group, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Magdalena Ganz
- Bioimaging Center, University of Konstanz, Konstanz, Germany
| | - David Marcellin
- Global Imaging Group, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Jens Richter
- Global Imaging Group, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Nicole Gerwin
- Musculoskeletal Disease Area, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Martin Rausch
- Global Imaging Group, Novartis Institutes for BioMedical Research, Basel, Switzerland
- * E-mail:
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15
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Fauconnier J, Roberge S, Saint N, Lacampagne A. Type 2 ryanodine receptor: A novel therapeutic target in myocardial ischemia/reperfusion. Pharmacol Ther 2013; 138:323-32. [DOI: 10.1016/j.pharmthera.2013.01.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 01/22/2013] [Indexed: 10/27/2022]
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16
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Cardiac ion channels and mechanisms for protection against atrial fibrillation. Rev Physiol Biochem Pharmacol 2013; 162:1-58. [PMID: 21987061 DOI: 10.1007/112_2011_3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Atrial fibrillation (AF) is recognised as the most common sustained cardiac arrhythmia in clinical practice. Ongoing drug development is aiming at obtaining atrial specific effects in order to prevent pro-arrhythmic, devastating ventricular effects. In principle, this is possible due to a different ion channel composition in the atria and ventricles. The present text will review the aetiology of arrhythmias with focus on AF and include a description of cardiac ion channels. Channels that constitute potentially atria-selective targets will be described in details. Specific focus is addressed to the recent discovery that Ca(2+)-activated small conductance K(+) channels (SK channels) are important for the repolarisation of atrial action potentials. Finally, an overview of current pharmacological treatment of AF is included.
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17
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Sacherer M, Sedej S, Wakuła P, Wallner M, Vos MA, Kockskämper J, Stiegler P, Sereinigg M, von Lewinski D, Antoons G, Pieske BM, Heinzel FR. JTV519 (K201) reduces sarcoplasmic reticulum Ca²⁺ leak and improves diastolic function in vitro in murine and human non-failing myocardium. Br J Pharmacol 2013; 167:493-504. [PMID: 22509897 DOI: 10.1111/j.1476-5381.2012.01995.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE Ca²⁺ leak from the sarcoplasmic reticulum (SR) via ryanodine receptors (RyR2s) contributes to cardiomyocyte dysfunction. RyR2 Ca²⁺ leak has been related to RyR2 phosphorylation. In these conditions, JTV519 (K201), a 1,4-benzothiazepine derivative and multi-channel blocker, stabilizes RyR2s and decrease SR Ca²⁺ leak. We investigated whether JTV519 stabilizes RyR2s without increasing RyR2 phosphorylation in mice and in non-failing human myocardium and explored underlying mechanisms. EXPERIMENTAL APPROACH SR Ca²⁺ leak was induced by ouabain in murine cardiomyocytes. [Ca²⁺]-transients, SR Ca²⁺ load and RyR2-mediated Ca²⁺ leak (sparks/waves) were quantified, with or without JTV519 (1 µmol·L⁻¹). Contribution of Ca²⁺ -/calmodulin-dependent kinase II (CaMKII) was assessed by KN-93 and Western blot (RyR2-Ser(2814) phosphorylation). Effects of JTV519 on contractile force were investigated in non-failing human ventricular trabeculae. KEY RESULTS Ouabain increased systolic and diastolic cytosolic [Ca²⁺](i) , SR [Ca²⁺], and SR Ca²⁺ leak (Ca²⁺ spark (SparkF) and Ca²⁺ wave frequency), independently of CaMKII and RyR-Ser(2814) phosphorylation. JTV519 decreased SparkF but also SR Ca²⁺ load. At matched SR [Ca²⁺], Ca²⁺ leak was significantly reduced by JTV519, but it had no effect on fractional Ca²⁺ release or Ca²⁺ wave propagation velocity. In human muscle, JTV519 was negatively inotropic at baseline but significantly enhanced ouabain-induced force and reduced its deleterious effects on diastolic function. CONCLUSIONS AND IMPLICATIONS JTV519 was effective in reducing SR Ca²⁺ leak by specifically regulating RyR2 opening at diastolic [Ca²⁺](i) in the absence of increased RyR2 phosphorylation at Ser(2814) , extending the potential use of JTV519 to conditions of acute cellular Ca²⁺ overload.
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Affiliation(s)
- M Sacherer
- Division of Cardiology, Medical University of Graz, Austria
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18
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Kim JJ, Němec J, Papp R, Strongin R, Abramson JJ, Salama G. Bradycardia alters Ca(2+) dynamics enhancing dispersion of repolarization and arrhythmia risk. Am J Physiol Heart Circ Physiol 2013; 304:H848-60. [PMID: 23316064 DOI: 10.1152/ajpheart.00787.2012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Bradycardia prolongs action potential (AP) durations (APD adaptation), enhances dispersion of repolarization (DOR), and promotes tachyarrhythmias. Yet, the mechanisms responsible for enhanced DOR and tachyarrhythmias remain largely unexplored. Ca(2+) transients and APs were measured optically from Langendorff rabbit hearts at high (150 × 150 μm(2)) or low (1.5 × 1.5 cm(2)) magnification while pacing at a physiological (120 beats/min) or a slow heart rate (SHR = 50 beats/min). Western blots and pharmacological interventions were used to elucidate the regional effects of bradycardia. As a result, bradycardia (SHR 50 beats/min) increased APDs gradually (time constant τf→s = 48 ± 9.2 s) and caused a secondary Ca(2+) release (SCR) from the sarcoplasmic reticulum during AP plateaus, occurring at the base on average of 184.4 ± 9.7 ms after the Ca(2+) transient upstroke. In subcellular imaging, SCRs were temporally synchronous and spatially homogeneous within myocytes. In diastole, SHR elicited variable asynchronous sarcoplasmic reticulum Ca(2+) release events leading to subcellular Ca(2+) waves, detectable only at high magnification. SCR was regionally heterogeneous, correlated with APD prolongation (P < 0.01, n = 5), enhanced DOR (r = 0.9277 ± 0.03, n = 7), and was gradually reversed by pacing at 120 beats/min along with APD shortening (P < 0.05, n = 5). A stabilizer of leaky ryanodine receptors (RyR2), 3-(4-benzylcyclohexyl)-1-(7-methoxy-2,3-dihydrobenzo[f][1,4]thiazepin-4(5H)-yl)propan-1-one (K201; 1 μM), suppressed SCR and reduced APD at the base, thereby reducing DOR (P < 0.02, n = 5). Ventricular ectopy induced by bradycardia (n = 5/15) was suppressed by K201. Western blot analysis revealed spatial differences of voltage-gated L-type Ca(2+) channel protein (Cav1.2α), Na(+)-Ca(2+) exchange (NCX1), voltage-gated Na(+) channel (Nav1.5), and rabbit ether-a-go-go-related (rERG) protein [but not RyR2 or sarcoplasmic reticulum Ca(2+) ATPase 2a] that correlate with the SCR distribution and explain the molecular basis for SCR heterogeneities. In conclusion, acute bradycardia elicits synchronized subcellular SCRs of sufficient magnitude to overcome the source-sink mismatch and to promote afterdepolarizations.
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Affiliation(s)
- Jong J Kim
- Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15261, USA
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19
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Otani N, Matsuda R, Oda K, Nishino S, Inoue T, Kaneko N. Protective effect of K201 on isoproterenol-induced and ischemic-reperfusion-induced ventricular arrhythmias in the rat: comparison with diltiazem. J Cardiovasc Pharmacol Ther 2012; 18:184-90. [PMID: 23144205 DOI: 10.1177/1074248412465489] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
AIM Ventricular arrhythmia (VA) is a risk for sudden death. Polymorphic ventricular tachycardia (VT) degenerating to ventricular fibrillation occurs subsequent to the prolongation of the QT interval following administration of catecholamines under Ca(2+) loading. Fatal VA also occurs in ischemia and ischemic-reperfusion. We compared the suppressive effect of K201 (JTV519), a multiple-channel blocker and cardiac ryanodine receptor-calcium release channel (RyR2) stabilizer, with that of diltiazem, a Ca(2+ )channel blocker, in 2 studies of isoproterenol-induced (n = 30) and ischemic-reperfusion-induced VAs (n = 38) in rats. METHODS Adult male Wistar rats were administered 12 mg/kg/min calcium chloride (CaCl(2)) for 20 minutes and then 6 μg/kg/min isoproterenol was infused with CaCl(2) for a further 20 minutes. In other rats, the left coronary artery was ligated for 5 minutes followed by reperfusion for 20 minutes. K201 or diltiazem (both 1 mg/kg) was administered before infusion of the isoproterenol or induction of ischemia. RESULTS After administration of isoproterenol under Ca(2+) loading, fatal VA frequently occurred in the vehicle (9 of 10 animals, 90%) and diltiazem (8 of 10, 80%) groups, and K201 significantly suppressed the incidences of arrhythmia and mortality (2 of 10, 20%). In the reperfusion study, the incidence and the time until occurrence of reperfusion-induced VA and mortality were significantly suppressed in the K201 (2 of 15 animals, 13%) and diltiazem (1 of 9 animals, 11%) groups compared to the vehicle group (8 of 14 animals, 57%). SIGNIFICANCE Induction of VA in an experimental model was achieved with a low dose of isoproterenol under Ca(2+) loading. K201 markedly suppressed both the isoproterenol-induced and the reperfusion-induced VAs, whereas diltiazem did not suppress the isoproterenol-induced VA. The results suggest that both VAs are related to early after depolarization (EAD) and indicate that K201 has the potential to suppress EAD by stabilizing RyR2 to mediate Ca(2+) release from the sarcoplasmic reticulum and acting as a multiple-channel blocker.
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Affiliation(s)
- Naoyuki Otani
- Department of Cardiovascular Medicine, Dokkyo Medical University, Kitakobayashi, Tochigi, Japan
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20
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Venetucci L, Denegri M, Napolitano C, Priori SG. Inherited calcium channelopathies in the pathophysiology of arrhythmias. Nat Rev Cardiol 2012; 9:561-75. [DOI: 10.1038/nrcardio.2012.93] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Kelly A, Elliott EB, Matsuda R, Kaneko N, Smith GL, Loughrey CM. The effect of K201 on isolated working rabbit heart mechanical function during pharmacologically induced Ca2+ overload. Br J Pharmacol 2012; 165:1068-83. [PMID: 21658026 DOI: 10.1111/j.1476-5381.2011.01531.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE Reduced cardiac contractility has been associated with disrupted myocardial Ca(2+) signalling. The 1,4 benzothiazepine K201 (JTV-519) acts on several Ca(2+) handling proteins and improves cardiac contractility in vivo in a variety of animal models of myocardial dysfunction. However, it is unclear whether this improvement depends on the systemic effects of K201 or if K201 reverses the effects of Ca(2+) dysregulation, regardless of the cause. EXPERIMENTAL APPROACH The effect of K201 on cardiac mechanical function was assessed in isolated working hearts from adult rabbits, using a ventricular pressure-volume catheter. In separate experiments, the effect of K201 was investigated in hearts following pharmacologically induced Ca(2+) overload using elevated extracellular [Ca(2+) ] ([Ca(2+) ](o) ) and β-adrenoceptor stimulation. KEY RESULTS K201 induced a concentration-dependent decline in systolic function (peak pressure, dP/dt(max) and preload recruitable stroke work), lusitropy (reduced dP/dt(min) and increased end diastolic pressure) and stroke volume, independent of decreased heart rate. In separate experiments, mechanical function in hearts exposed to 4.5 mmol·L(-1) [Ca(2+) ](o) and 150 nmol·L(-1) isoprenaline declined until cessation of aortic flow (in 6 out of 11 hearts). However, all hearts perfused with the addition of 1 µmol·L(-1) K201 maintained aortic flow and demonstrated significantly improved peak systolic pressures, dP/dt(max) and dP/dt(min) . CONCLUSIONS AND IMPLICATIONS K201 significantly improved mechanical function of the heart during Ca(2+) overload. This suggests that K201 can limit the detrimental effects of elevated intracellular Ca(2+) and exert beneficial effects on cardiac contractile function, independent of systemic effects previously observed in vivo.
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Affiliation(s)
- A Kelly
- Institute of Cardiovascular & Medical Sciences, University of Glasgow, Glasgow, UK
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Elliott EB, Kelly A, Smith GL, Loughrey CM. Isolated rabbit working heart function during progressive inhibition of myocardial SERCA activity. Circ Res 2012; 110:1618-27. [PMID: 22556337 DOI: 10.1161/circresaha.111.262337] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE The extent to which sarcoplasmic reticulum Ca(2+)ATPase (SERCA) activity alone determines left ventricular (LV) pump function is unknown. OBJECTIVE To correlate SERCA activity with hemodynamic function of rabbit LV during thapsigargin perfusion. METHODS AND RESULTS Isolated rabbit hearts were perfused in working heart configuration, and LV pump function was assessed using a pressure-volume catheter. Rapid and complete (>95%) inhibition of SERCA was associated with a moderate decrease in cardiac function (to 70%-85% of control). Further decrease in cardiac function to 50%-75% of control occurred over the next ≈ 30 minutes despite no detectable further inhibition of SERCA activity. Analysis of the 20 seconds prior to pump failure revealed a rapid decrease in end diastolic volume. Intermediate levels of SERCA function (≈ 50% of control) had only minor hemodynamic effects. Parallel experiments in field-stimulated isolated ventricular cardiomyocytes monitored intracellular Ca(2+) and cell shortening. On perfusion with thapsigargin, Ca(2+) transient amplitude and cell shortening fell to ≈ 70% of control followed by increased diastolic Ca(2+) concentration and diastolic cell shortening to achieve a new steady state. CONCLUSIONS The relationship between SERCA activity and LV function in the rabbit is highly nonlinear. In the short term, only moderate effects on LV pump function were observed despite almost complete (>95%) reduction in SERCA activity. The terminal decline of function was associated with sudden sustained increase in diastolic tone comparable to the sustained contraction observed in isolated cardiomyocytes. Secondary increases of intracellular Ca(2+) and Na(+) following complete SERCA inhibition eventually limit contractile function and precipitate LV pump failure.
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Affiliation(s)
- Elspeth B Elliott
- Institute of Cardiovascular & Medical Sciences, West Medical Building, University of Glasgow, G12 8QQ, UK
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23
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Thomas NL, Williams AJ. Pharmacology of ryanodine receptors and Ca2+-induced Ca2+ release. ACTA ACUST UNITED AC 2012. [DOI: 10.1002/wmts.34] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Alternative strategies in arrhythmia therapy: evaluation of Na/Ca exchange as an anti-arrhythmic target. Pharmacol Ther 2011; 134:26-42. [PMID: 22197992 DOI: 10.1016/j.pharmthera.2011.12.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 11/22/2011] [Accepted: 11/22/2011] [Indexed: 01/08/2023]
Abstract
The search for alternative anti-arrhythmic strategies is fueled by an unmet medical need as well as by the opportunities arising from identification of novel targets and novel drugs. Na/Ca exchange is a potential target involved in several types of arrhythmias, such as those related to ischemia-reperfusion, heart failure and also some forms of genetic arrhythmias. Inhibition of Na/Ca exchange is theoretically not only anti-arrhythmic but also increases cellular Ca(2+) content. This could be an advantage in conditions of low inotropy, such as in heart failure, but may also worsen conditions such as the recovery from ischemia or relaxation abnormalities. With the available drugs such as KB-R7943 and SEA-0400 these theories have now been tested in a number of cellular and in vivo models. Experience is overall rather positive and seems less hampered by the potential drawbacks than expected. This may be because the currently available drugs are not highly selective, with additional benefit derived from concurrent effects. While this precludes a definite answer regarding the benefit of a pure NCX inhibitor, they indicate that Na/Ca exchange inhibition as part of a multi-target strategy is an avenue to be considered. Such studies will need further 'bench' work and testing in relevant preclinical models, including chronic disease.
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Kemi OJ, MacQuaide N, Hoydal MA, Ellingsen O, Smith GL, Wisloff U. Exercise training corrects control of spontaneous calcium waves in hearts from myocardial infarction heart failure rats. J Cell Physiol 2011; 227:20-6. [DOI: 10.1002/jcp.22771] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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26
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Stams TRG, Oros A, der Nagel RV, Beekman JDM, Chamberlin P, Dittrich HC, Vos MA. Effects of K201 on repolarization and arrhythmogenesis in anesthetized chronic atrioventricular block dogs susceptible to dofetilide-induced torsade de pointes. Eur J Pharmacol 2011; 672:126-34. [PMID: 22001562 DOI: 10.1016/j.ejphar.2011.09.180] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Revised: 09/21/2011] [Accepted: 09/24/2011] [Indexed: 11/16/2022]
Abstract
The novel antiarrhythmic drug K201 (4-[3-{1-(4-benzyl)piperidinyl}propionyl]-7-methoxy-2,3,4,5-tetrahydro-1,4-benzothiazepine monohydrochloride) is currently in development for treatment of atrial fibrillation. K201 not only controls intracellular calcium release by the ryanodine receptors, but also possesses a ventricular action that might predispose to torsade de pointes arrhythmias. The anti- and proarrhythmic effects of K201 were investigated in the anesthetized canine chronic atrioventricular block model. Two doses of K201 (0.1 and 0.3mg/kg/2 min followed by 0.01 and 0.03 mg/kg/30 min i.v.) were tested in 4 serial experiments in dogs with normally conducted sinus rhythm (n=10) and in torsade de pointes-susceptible dogs with chronic atrioventricular block. Susceptibility was assessed with dofetilide (0.025 mg/kg/5 min i.v.). Beat-to-beat variability of repolarization was quantified as short-term variability of left ventricular monophasic action potential duration. In dogs with normally conducted sinus rhythm, both doses of K201 prolonged ventricular repolarization whereas only the higher dose prolonged atrial repolarization. At chronic atrioventricular block, dofetilide induced torsade de pointes in 9 of 10 dogs. K201 did neither suppress nor prevent dofetilide-induced torsade de pointes. K201 dose-dependently prolonged ventricular repolarization. In contrary to the lower dose, the higher dose did increase beat-to-beat variability of repolarization (from 1.2 ± 0.3 to 2.9 ± 0.8 ms, P<0.05) and resulted in spontaneous, repetitive torsade de pointes arrhythmias in 1 of 7 dogs; Programmed electrical stimulation resulted in torsade de pointes in 2 more dogs. In conclusion, both doses of K201 showed a class III effect. No relevant antiarrhythmic effects against dofetilide-induced torsade de pointes were seen. Only at the higher dose a proarrhythmic signal was observed.
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Affiliation(s)
- Thom R G Stams
- Department of Medical Physiology, Division Heart and Lungs, University Medical Center Utrecht, Yalelaan 50, 3584 CM Utrecht, The Netherlands.
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Elliott EB, Hasumi H, Otani N, Matsuda T, Matsuda R, Kaneko N, Smith GL, Loughrey CM. K201 (JTV-519) alters the spatiotemporal properties of diastolic Ca(2+) release and the associated diastolic contraction during β-adrenergic stimulation in rat ventricular cardiomyocytes. Basic Res Cardiol 2011; 106:1009-22. [PMID: 21901290 PMCID: PMC3228956 DOI: 10.1007/s00395-011-0218-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Revised: 07/24/2011] [Accepted: 08/20/2011] [Indexed: 11/25/2022]
Abstract
K201 has previously been shown to reduce diastolic contractions in vivo during β-adrenergic stimulation and elevated extracellular calcium concentration ([Ca2+]o). The present study characterised the effect of K201 on electrically stimulated and spontaneous diastolic sarcoplasmic reticulum (SR)-mediated Ca2+ release and contractile events in isolated rat cardiomyocytes during β-adrenergic stimulation and elevated [Ca2+]o. Parallel experiments using confocal microscopy examined spontaneous diastolic Ca2+ release events at an enhanced spatiotemporal resolution. 1.0 μmol/L K201 in the presence of 150 nmol/L isoproterenol (ISO) and 4.75 mmol/L [Ca2+]o significantly decreased the amplitude of diastolic contractions to ~16% of control levels. The stimulated free Ca2+ transient amplitude was significantly reduced, but stimulated cell shortening was not significantly altered. When intracellular buffering was taken into account, K201 led to an increase in action potential-induced SR Ca2+ release. Myofilament sensitivity to Ca2+ was not changed by K201. Confocal microscopy revealed diastolic events composed of multiple Ca2+ waves (2–3) originating at various points along the cardiomyocyte length during each diastolic period. 1.0 μmol/L K201 significantly reduced the (a) frequency of diastolic events and (b) initiation points/diastolic interval in the remaining diastolic events to 61% and 71% of control levels respectively. 1.0 μmol/L K201 can reduce the probability of spontaneous diastolic Ca2+ release and their associated contractions which may limit the propensity for the contractile dysfunction observed in vivo.
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Affiliation(s)
- E. B. Elliott
- Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, University Place, Glasgow, G12 8TA UK
| | - H. Hasumi
- Department of Cardiovascular Medicine, Dokkyo Medical University School of Medicine, 880 Kitakobayashi, Mibu, Tochigi Japan
| | - N. Otani
- Department of Cardiovascular Medicine, Dokkyo Medical University School of Medicine, 880 Kitakobayashi, Mibu, Tochigi Japan
| | - T. Matsuda
- Department of Cardiovascular Medicine, Dokkyo Medical University School of Medicine, 880 Kitakobayashi, Mibu, Tochigi Japan
| | - R. Matsuda
- Department of Preventative Medical Sciences for the Heart, Dokkyo Medical University School of Medicine, 880 Kitakobayashi, Mibu, Tochigi Japan
| | - N. Kaneko
- Utsunomiya Memorial Hospital, Utsunomiya, Japan
| | - G. L. Smith
- Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, University Place, Glasgow, G12 8TA UK
| | - Christopher M. Loughrey
- Institute of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, University Place, Glasgow, G12 8TA UK
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Two candidates at the heart of dysfunction: The ryanodine receptor and calcium/calmodulin protein kinase II as potential targets for therapeutic intervention—An in vivo perspective. Pharmacol Ther 2011; 131:204-20. [DOI: 10.1016/j.pharmthera.2011.02.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Accepted: 02/17/2011] [Indexed: 11/19/2022]
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Galimberti ES, Knollmann BC. Efficacy and potency of class I antiarrhythmic drugs for suppression of Ca2+ waves in permeabilized myocytes lacking calsequestrin. J Mol Cell Cardiol 2011; 51:760-8. [PMID: 21798265 DOI: 10.1016/j.yjmcc.2011.07.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 05/31/2011] [Accepted: 07/05/2011] [Indexed: 02/08/2023]
Abstract
Ca(2+) waves can trigger ventricular arrhythmias such as catecholaminergic-polymorphic ventricular tachycardia (CPVT). Drugs that prevent Ca(2+) waves may have antiarrhythmic properties. Here, we use permeabilized ventricular myocytes from a CPVT mouse model lacking calsequestrin (casq2) to screen all clinically available class I antiarrhythmic drugs and selected other antiarrhythmic agents for activity against Ca(2+) waves. Casq2-/- myocytes were imaged in line-scan mode and the following Ca(2+) wave parameters analyzed: wave incidence, amplitude, frequency, and propagation speed. IC(50) (potency) and maximum inhibition (efficacy) were calculated for each drug. Drugs fell into 3 distinct categories. Category 1 drugs (flecainide and R-propafenone) suppressed wave parameters with the highest potency (IC(50)<10 μM) and efficacy (>50% maximum wave inhibition). Category 2 drugs (encainide, quinidine, lidocaine, and verapamil) had intermediate potency (IC(50) 20-40 μM) and efficacy (20-40% maximum wave inhibition). Category 3 drugs (procainamide, disopyramide, mexiletine, cibenzoline, and ranolazine) had no significant effects on Ca(2+) waves at the highest concentration tested (100 μM). Propafenone was stereoselective, with R-propafenone suppressing waves more potently than S-propafenone (IC(50): R-propafenone 2 ± 0.2 μM vs. S-propafenone 54 ± 18 μM). Both flecainide and R-propafenone decreased Ca(2+) spark mass and converted propagated Ca(2+) waves into non-propagated wavelets and frequent sparks, suggesting that reduction in spark mass, not spark frequency, was responsible for wave suppression. Among all class I antiarrhythmic drugs, flecainide and R-propafenone inhibit Ca(2+) waves with the highest potency and efficacy. Permeabilized casq2-/- myocytes are a simple in-vitro assay for finding drugs with activity against Ca(2+) waves. This article is part of a Special Issue entitled 'Possible Editorial'.
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Affiliation(s)
- Eleonora Savio Galimberti
- Division of Clinical Pharmacology and Oates Institute for Experimental Therapeutics, Vanderbilt University School of Medicine, Nashville, USA
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Workman AJ, Smith GL, Rankin AC. Mechanisms of termination and prevention of atrial fibrillation by drug therapy. Pharmacol Ther 2011; 131:221-41. [PMID: 21334377 DOI: 10.1016/j.pharmthera.2011.02.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Accepted: 02/09/2011] [Indexed: 01/13/2023]
Abstract
Atrial fibrillation (AF) is a disorder of the rhythm of electrical activation of the cardiac atria. It is the most common cardiac arrhythmia, has multiple aetiologies, and increases the risk of death from stroke. Pharmacological therapy is the mainstay of treatment for AF, but currently available anti-arrhythmic drugs have limited efficacy and safety. An improved understanding of how anti-arrhythmic drugs affect the electrophysiological mechanisms of AF initiation and maintenance, in the setting of the different cardiac diseases that predispose to AF, is therefore required. A variety of animal models of AF has been developed, to represent and control the pathophysiological causes and risk factors of AF, and to permit the measurement of detailed and invasive parameters relating to the associated electrophysiological mechanisms of AF. The purpose of this review is to examine, consolidate and compare available relevant data on in-vivo electrophysiological mechanisms of AF suppression by currently approved and investigational anti-arrhythmic drugs in such models. These include the Vaughan Williams class I-IV drugs, namely Na(+) channel blockers, β-adrenoceptor antagonists, action potential prolonging drugs, and Ca(2+) channel blockers; the "upstream therapies", e.g., angiotensin converting enzyme inhibitors, statins and fish oils; and a variety of investigational drugs such as "atrial-selective" multiple ion channel blockers, gap junction-enhancers, and intracellular Ca(2+)-handling modulators. It is hoped that this will help to clarify the main electrophysiological mechanisms of action of different and related drug types in different disease settings, and the likely clinical significance and potential future exploitation of such mechanisms.
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Affiliation(s)
- A J Workman
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, 126 University Place, Glasgow G12 8TA, United Kingdom.
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Neumann JT, Diaz-Sylvester PL, Fleischer S, Copello JA. CGP-37157 inhibits the sarcoplasmic reticulum Ca²+ ATPase and activates ryanodine receptor channels in striated muscle. Mol Pharmacol 2010; 79:141-7. [PMID: 20923851 DOI: 10.1124/mol.110.067165] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
7-Chloro-5-(2-chlorophenyl)-1,5-dihydro-4,1-benzothiazepin-2(3H)-one [CGP-37157 (CGP)], a benzothiazepine derivative of clonazepam, is commonly used as a blocker of the mitochondrial Na+/Ca²+ exchanger. However, evidence suggests that CGP could also affect other targets, such as L-type Ca²+ channels and plasmalemma Na+/Ca²+ exchanger. Here, we tested the possibility of a direct modulation of ryanodine receptor channels (RyRs) and/or sarco/endoplasmic reticulum Ca²+-stimulated ATPase (SERCA) by CGP. In the presence of ruthenium red (inhibitor of RyRs), CGP decreased SERCA-mediated Ca²+ uptake of cardiac and skeletal sarcoplasmic reticulum (SR) microsomes (IC₅₀ values of 6.6 and 9.9 μM, respectively). The CGP effects on SERCA activity correlated with a decreased V(max) of ATPase activity of SERCA-enriched skeletal SR fractions. CGP (≥ 5 μM) also increased RyR-mediated Ca²+ leak from skeletal SR microsomes. Planar bilayer studies confirmed that both cardiac and skeletal RyRs are directly activated by CGP (EC(50) values of 9.4 and 12.0 μM, respectively). In summary, we found that CGP inhibits SERCA and activates RyR channels. Hence, the action of CGP on cellular Ca²+ homeostasis reported in the literature of cardiac, skeletal muscle, and other nonmuscle systems requires further analysis to take into account the contribution of all CGP-sensitive Ca²+ transporters.
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Affiliation(s)
- Jake T Neumann
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, Illinois, USA
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Ryanodine receptor calcium channels and their partners as drug targets. Biochem Pharmacol 2010; 79:1535-43. [DOI: 10.1016/j.bcp.2010.01.014] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Revised: 01/14/2010] [Accepted: 01/14/2010] [Indexed: 11/22/2022]
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Ryanodine receptor studies using genetically engineered mice. FEBS Lett 2010; 584:1956-65. [PMID: 20214899 DOI: 10.1016/j.febslet.2010.03.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Revised: 02/24/2010] [Accepted: 03/03/2010] [Indexed: 11/20/2022]
Abstract
Ryanodine receptors (RyR) regulate intracellular Ca(2+) release in many cell types and have been implicated in a number of inherited human diseases. Over the past 15 years genetically engineered mouse models have been developed to elucidate the role that RyRs play in physiology and pathophysiology. To date these models have implicated RyRs in fundamental biological processes including excitation-contraction coupling and long term plasticity as well as diseases including malignant hyperthermia, cardiac arrhythmias, heart failure, and seizures. In this review we summarize the RyR mouse models and how they have enhanced our understanding of the RyR channels and their roles in cellular physiology and disease.
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Thomas NL, Maxwell C, Mukherjee S, Williams AJ. Ryanodine receptor mutations in arrhythmia: The continuing mystery of channel dysfunction. FEBS Lett 2010; 584:2153-60. [PMID: 20132818 DOI: 10.1016/j.febslet.2010.01.057] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 01/27/2010] [Accepted: 01/29/2010] [Indexed: 11/13/2022]
Abstract
Mutations in RyR2 are causative of an inherited disorder which often results in sudden cardiac death. Dysfunctional channel behaviour has been the subject of many investigations varying from single channel analysis through to complex animal models. This review discusses recent advances in the field, describes the controversy surrounding the exact consequences of RyR2 mutation and how the disparate data may be reconciled. This heterogeneity of function with respect to the effects of polymorphisms, phosphorylation, cytosolic and luminal Ca(2+) as well as inter-domain interactions may have important implications for the recent pharmaceutical therapies which have been put forward. We surmise that a comprehensive characterisation of mutations on a case-by-case basis may be beneficial for the development of specifically targeted therapies.
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Affiliation(s)
- N Lowri Thomas
- Department of Cardiology, Wales Heart Research Institute, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.
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Sedej S, Heinzel FR, Walther S, Dybkova N, Wakula P, Groborz J, Gronau P, Maier LS, Vos MA, Lai FA, Napolitano C, Priori SG, Kockskämper J, Pieske B. Na+-dependent SR Ca2+ overload induces arrhythmogenic events in mouse cardiomyocytes with a human CPVT mutation. Cardiovasc Res 2010; 87:50-9. [PMID: 20080988 DOI: 10.1093/cvr/cvq007] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS Mutations in the cardiac ryanodine receptor Ca(2+) release channel, RyR2, underlie catecholaminergic polymorphic ventricular tachycardia (CPVT), an inherited life-threatening arrhythmia. CPVT is triggered by spontaneous RyR2-mediated sarcoplasmic reticulum (SR) Ca(2+) release in response to SR Ca(2+) overload during beta-adrenergic stimulation. However, whether elevated SR Ca(2+) content--in the absence of protein kinase A activation--affects RyR2 function and arrhythmogenesis in CPVT remains elusive. METHODS AND RESULTS Isolated murine ventricular myocytes harbouring a human RyR2 mutation (RyR2(R4496C+/-)) associated with CPVT were investigated in the absence and presence of 1 micromol/L JTV-519 (RyR2 stabilizer) followed by 100 micromol/L ouabain intervention to increase cytosolic [Na(+)] and SR Ca(2+) load. Changes in membrane potential and intracellular [Ca(2+)] were monitored with whole-cell patch-clamping and confocal Ca(2+) imaging, respectively. At baseline, action potentials (APs), Ca(2+) transients, fractional SR Ca(2+) release, and SR Ca(2+) load were comparable in wild-type (WT) and RyR2(R4496C+/-) myocytes. Ouabain evoked significant increases in diastolic [Ca(2+)], peak systolic [Ca(2+)], fractional SR Ca(2+) release, and SR Ca(2+) content that were quantitatively similar in WT and RyR2(R4496C+/-) myocytes. Ouabain also induced arrhythmogenic events, i.e. spontaneous Ca(2+) waves, delayed afterdepolarizations and spontaneous APs, in both groups. However, the ouabain-induced increase in the frequency of arrhythmogenic events was dramatically larger in RyR2(R4496C+/-) when compared with WT myocytes. JTV-519 greatly reduced the frequency of ouabain-induced arrhythmogenic events. CONCLUSION The elevation of SR Ca(2+) load--in the absence of beta-adrenergic stimulation--is sufficient to increase the propensity for triggered arrhythmias in RyR2(R4496C+/-) cardiomyocytes. Stabilization of RyR2 by JTV-519 effectively reduces these triggered arrhythmias.
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Affiliation(s)
- Simon Sedej
- Division of Cardiology, Medical University of Graz, Auenbruggerplatz 15, Graz A-8036, Austria
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Hirose M, Stuyvers BD, Dun W, ter Keurs HEDJ, Boyden PA. Function of Ca(2+) release channels in Purkinje cells that survive in the infarcted canine heart: a mechanism for triggered Purkinje ectopy. Circ Arrhythm Electrophysiol 2009; 1:387-95. [PMID: 19753099 DOI: 10.1161/circep.107.758110] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Triggered Purkinje ectopy can lead to the initiation of serious ventricular arrhythmias in post-myocardial infarction patients. In the canine model, Purkinje cells from the subendocardial border of the healing infarcted heart can initiate ventricular arrhythmias. Intracellular Ca(2+) abnormalities underlie these arrhythmias, yet the subcellular reasons for these abnormalities remain unknown. METHODS AND RESULTS Using 2D confocal microscopy, we directly quantify and compare typical spontaneous Ca(2+) events in specific subcellular regions of normal Purkinje cells with those Purkinje cells from the subendocardium of the 48-hour infarcted canine heart (IZPCs). The Ca(2+) event rate was higher in the subsarcolemmal region of IZPCs when compared with normal Purkinje cells; IZPC amplitudes were higher, yet the spatial extents of these events were similar. The amplitude of caffeine-releasable Ca(2+) in either the subsarcolemmal or core regions of IZPCs did not differ from normal Purkinje cells, suggesting that Ca(2+) overload was not related to the frequency change. In permeabilized Purkinje cells from both groups, the event rate was related to free [Ca(2+)] in both subsarcolemmal and core, but in IZPCs, this event rate was significantly increased at each free Ca(2+), suggesting an enhanced sensitivity to Ca(2+) release. Furthermore, decays of wide long lasting Ca(2+) release events in IZPC's core were significantly accelerated compared with those in normal Purkinje cells. JTV519 (K201) suppressed IZPC cell wide Ca(2+) waves as well as normalized the enhanced event rate and its response to free Ca(2+). CONCLUSIONS Increased spontaneous Ca(2+) release events in IZPCs are due to uniform regionally increased Ca(2+) release channel sensitivity to Ca(2+) without a change in sarcoplasmic reticulum content. In addition, Ca(2+) reuptake in IZPCs is accelerated. These properties would lower the threshold of Ca(2+) release channels, setting the stage for the highly frequent arrhythmogenic cell wide Ca(2+) waves observed in IZPCs.
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Affiliation(s)
- Masanori Hirose
- Department of Pharmacology, Center for Molecular Therapeutics, Columbia University, New York, NY, USA
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MacMillan D, McCarron JG. Regulation by FK506 and rapamycin of Ca2+ release from the sarcoplasmic reticulum in vascular smooth muscle: the role of FK506 binding proteins and mTOR. Br J Pharmacol 2009; 158:1112-20. [PMID: 19785652 DOI: 10.1111/j.1476-5381.2009.00369.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE The sarcoplasmic reticulum (SR), regulates the cytoplasmic Ca(2+) concentration ([Ca(2+)](cyto)) in vascular smooth muscle. Release from the SR is controlled by two intracellular receptor/channel complexes, the ryanodine receptor (RyR) and the inositol 1,4,5-trisphosphate receptor (IP(3)R). These receptors may be regulated by the accessory FK506-binding protein (FKBP) either directly, by binding to the channel, or indirectly via FKBP modulation of two targets, the phosphatase, calcineurin or the kinase, mammalian target of rapamycin (mTOR). EXPERIMENTAL APPROACH Single portal vein myocytes were voltage-clamped in whole cell configuration and [Ca(2+)](cyto) measured using fluo-3. IP(3)Rs were activated by photolysis of caged IP(3) and RyRs activated by hydrostatic application of caffeine. KEY RESULTS FK506 which displaces FKBP from each receptor (to inhibit calcineurin) increased the [Ca(2+)](cyto) rise evoked by activation of either RyR or IP(3)R. Rapamycin which displaces FKBP (to inhibit mTOR) also increased the amplitude of the caffeine-evoked, but reduced the IP(3)-evoked [Ca(2+)](cyto) rise. None of the phosphatase inhibitors, cypermethrin, okadaic acid or calcineurin inhibitory peptide, altered either caffeine- or IP(3)-evoked [Ca(2+)](cyto) release; calcineurin did not contribute to FK506-mediated potentiation of RyR- or IP(3)R-mediated Ca(2+) release. The mTOR inhibitor LY294002, like rapamycin, decreased IP(3)-evoked Ca(2+) release. CONCLUSIONS AND IMPLICATIONS Ca(2+) release in portal vein myocytes, via RyR, was modulated directly by FKBP binding to the channel; neither calcineurin nor mTOR contributed to this regulation. However, IP(3)R-mediated Ca(2+) release, while also modulated directly by FKBP may be additionally regulated by mTOR. Rapamycin inhibition of IP(3)-mediated Ca(2+) release may be explained by mTOR inhibition.
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Affiliation(s)
- D MacMillan
- Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, UK
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Toischer K, Lehnart SE, Tenderich G, Milting H, Körfer R, Schmitto JD, Schöndube FA, Kaneko N, Loughrey CM, Smith GL, Hasenfuss G, Seidler T. K201 improves aspects of the contractile performance of human failing myocardium via reduction in Ca2+ leak from the sarcoplasmic reticulum. Basic Res Cardiol 2009; 105:279-87. [PMID: 19718543 PMCID: PMC2807967 DOI: 10.1007/s00395-009-0057-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Revised: 08/06/2009] [Accepted: 08/20/2009] [Indexed: 11/30/2022]
Abstract
In heart failure, intracellular Ca2+ leak from cardiac ryanodine receptors (RyR2s) leads to a loss of Ca2+ from the sarcoplasmic reticulum (SR) potentially contributing to decreased function. Experimental data suggest that the 1,4-benzothiazepine K201 (JTV-519) may stabilise RyR2s and thereby reduce detrimental intracellular Ca2+ leak. Whether K201 exerts beneficial effects in human failing myocardium is unknown. Therefore, we have studied the effects of K201 on muscle preparations from failing human hearts. K201 (0.3 microM; extracellular [Ca2+]e 1.25 mM) showed no effects on contractile function and micromolar concentrations resulted in negative inotropic effects (K201 1 microM; developed tension -9.8 +/- 2.5% compared to control group; P < 0.05). Interestingly, K201 (0.3 microM) increased the post-rest potentiation (PRP) of failing myocardium after 120 s, indicating an increased SR Ca2+ load. At high [Ca2+]e concentrations (5 mmol/L), K201 increased PRP already at shorter rest intervals (30 s). Strikingly, treatment with K201 (0.3 microM) prevented diastolic dysfunction (diastolic tension at 5 mmol/L [Ca2+]e normalised to 1 mmol/L [Ca2+]e: control 1.26 +/- 0.06, K201 1.01 +/- 0.03, P < 0.01). In addition at high [Ca2+]e) K201 (0.3 microM) treatment significantly improved systolic function [developed tension +27 +/- 8% (K201 vs. control); P < 0.05]. The beneficial effects on diastolic and systolic functions occurred throughout the physiological frequency range of the human heart rate from 1 to 3 Hz. Upon elevated intracellular Ca2+ concentration, systolic and diastolic contractile functions of terminally failing human myocardium are improved by K201.
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Affiliation(s)
- Karl Toischer
- Abteilung Kardiologie und Pneumologie, Georg-August-Universität, Göttingen, Germany.
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Kaneko N, Matsuda R, Hata Y, Shimamoto K. Pharmacological characteristics and clinical applications of K201. ACTA ACUST UNITED AC 2009; 4:126-31. [PMID: 19442077 PMCID: PMC2841427 DOI: 10.2174/157488409788184972] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
K201 is a 1,4-benzothiazepine derivative that is a promising new drug with a strong cardioprotective effect. We initially discovered K201 as an effective suppressant of sudden cardiac cell death due to calcium overload. K201 is a non-specific blocker of sodium, potassium and calcium channels, and its cardioprotective effect is more marked than those of nicorandil, prazosine, propranolol, verapamil and diltiazem. Recently, K201 has also been shown to have activities indicated for treatment of atrial fibrillation, ventricular fibrillation, heart failure and ischemic heart disease, including action as a multiple-channel blocker, inhibition of diastolic Ca(2+) release from the sarcoplasmic reticulum, suppression of spontaneous Ca(2+) sparks and Ca(2+) waves, blockage of annexin V and provision of myocardial protection, and improvement of norepinephrine-induced diastolic dysfunction. Here, we describe the pharmacological characteristics and clinical applications of K201.
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Affiliation(s)
- Noboru Kaneko
- Department of Cardiology and Pneumology, Dokkyo Medical University, Tochigi, Japan.
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Blayney LM, Lai FA. Ryanodine receptor-mediated arrhythmias and sudden cardiac death. Pharmacol Ther 2009; 123:151-77. [PMID: 19345240 PMCID: PMC2704947 DOI: 10.1016/j.pharmthera.2009.03.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Accepted: 03/03/2009] [Indexed: 12/25/2022]
Abstract
The cardiac ryanodine receptor-Ca2+ release channel (RyR2) is an essential sarcoplasmic reticulum (SR) transmembrane protein that plays a central role in excitation–contraction coupling (ECC) in cardiomyocytes. Aberrant spontaneous, diastolic Ca2+ leak from the SR due to dysfunctional RyR2 contributes to the formation of delayed after-depolarisations, which are thought to underlie the fatal arrhythmia that occurs in both heart failure (HF) and in catecholaminergic polymorphic ventricular tachycardia (CPVT). CPVT is an inherited disorder associated with mutations in either the RyR2 or a SR luminal protein, calsequestrin. RyR2 shows normal function at rest in CPVT but the RyR2 dysfunction is unmasked by physical exercise or emotional stress, suggesting abnormal RyR2 activation as an underlying mechanism. Several potential mechanisms have been advanced to explain the dysfunctional RyR2 observed in HF and CPVT, including enhanced RyR2 phosphorylation status, altered RyR2 regulation at luminal/cytoplasmic sites and perturbed RyR2 intra/inter-molecular interactions. This review considers RyR2 dysfunction in the context of the structural and functional modulation of the channel, and potential therapeutic strategies to stabilise RyR2 function in cardiac pathology.
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Affiliation(s)
- Lynda M Blayney
- Wales Heart Research Institute, Cardiff University School of Medicine, Cardiff CF144XN, UK.
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