1
|
Casado-Arroyo R, Bernardi M, Sabouret P, Franculli G, Tamargo J, Spadafora L, Lellouche N, Biondi-Zoccai G, Toth PP, Banach M. Investigative agents for atrial fibrillation: agonists and stimulants, progress and expectations. Expert Opin Investig Drugs 2024; 33:967-978. [PMID: 39096248 DOI: 10.1080/13543784.2024.2388583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2024] [Revised: 07/10/2024] [Accepted: 08/01/2024] [Indexed: 08/05/2024]
Abstract
INTRODUCTION Atrial fibrillation (AF) is the most common type of cardiac arrhythmia. Its prevalence has increased due to worldwide populations that are aging in combination with the growing incidence of risk factors associated. Recent advances in our understanding of AF pathophysiology and the identification of nodal players involved in AF-promoting atrial remodeling highlights potential opportunities for new therapeutic approaches. AREAS COVERED This detailed review summarizes recent developments in the field antiarrhythmic drugs in the field AF. EXPERT OPINION The current situation is far than optimal. Despite clear unmet needs in drug development in the field of AF treatment, the current development of new drugs is absent. The need for a molecule with absence of cardiac and non-cardiac toxicity in the short and long term is a limitation in the field. Improvement in the understanding of AF genetics, pathophysiology, molecular alterations, big data and artificial intelligence with the objective to provide a personalized AF treatment will be the cornerstone of AF treatment in the coming years.
Collapse
Affiliation(s)
- Ruben Casado-Arroyo
- Department of Cardiology, H.U.B.-Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium
| | - Marco Bernardi
- Department of Clinical, Internal Medicine, Anesthesiology and Cardiovascular Sciences, Sapienza University of Rome, Rome, Italy
| | - Pierre Sabouret
- Heart Institute, ACTION Study Group-CHU Pitié-Salpétrière Paris, Paris, France
- Collège National des Cardiologues Français (CNCF), Paris, France
| | - Giuseppe Franculli
- Department of Clinical, Internal Medicine, Anesthesiology and Cardiovascular Sciences, Sapienza University of Rome, Rome, Italy
| | - Juan Tamargo
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense, Instituto De Investigación Sanitaria Gregorio Marañón, Madrid, Spain
| | - Luigi Spadafora
- Department of Clinical, Internal Medicine, Anesthesiology and Cardiovascular Sciences, Sapienza University of Rome, Rome, Italy
| | - Nicolas Lellouche
- Service de Cardiologie, AP-HP, University Hospital Henri Mondor, Créteil, France
| | - Giuseppe Biondi-Zoccai
- Department of Medical-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Latina, Italy
- Maria Cecilia Hospital, GVM Care & Research, Cotignola, Italy
| | - Peter P Toth
- CGH Medical Center, Sterling, IL, USA
- Cicarrone Center for the Prevention of Cardiovascular Disease, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Maciej Banach
- Department of Preventive Cardiology and Lipidology, Medical University of Lodz Lodz Poland, Lodz, Poland
- Department of Cardiology and Congenital Diseases of Adults, Polish Mother's Memorial Hospital Research Institute Lodz Poland, Lodz, Poland
| |
Collapse
|
2
|
Mitrokhin V, Hadzi-Petrushev N, Kazanski V, Schileyko S, Kamkina O, Rodina A, Zolotareva A, Zolotarev V, Kamkin A, Mladenov M. The Role of K ACh Channels in Atrial Fibrillation. Cells 2024; 13:1014. [PMID: 38920645 PMCID: PMC11201540 DOI: 10.3390/cells13121014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2024] [Revised: 06/05/2024] [Accepted: 06/07/2024] [Indexed: 06/27/2024] Open
Abstract
This manuscript explores the intricate role of acetylcholine-activated inward rectifier potassium (KACh) channels in the pathogenesis of atrial fibrillation (AF), a common cardiac arrhythmia. It delves into the molecular and cellular mechanisms that underpin AF, emphasizing the vital function of KACh channels in modulating the atrial action potential and facilitating arrhythmogenic conditions. This study underscores the dual nature of KACh activation and its genetic regulation, revealing that specific variations in potassium channel genes, such as Kir3.4 and K2P3.1, significantly influence the electrophysiological remodeling associated with AF. Furthermore, this manuscript identifies the crucial role of the KACh-mediated current, IKACh, in sustaining arrhythmia through facilitating shorter re-entry circuits and stabilizing the re-entrant circuits, particularly in response to vagal nerve stimulation. Experimental findings from animal models, which could not induce AF in the absence of muscarinic activation, highlight the dependency of AF induction on KACh channel activity. This is complemented by discussions on therapeutic interventions, where KACh channel blockers have shown promise in AF management. Additionally, this study discusses the broader implications of KACh channel behavior, including its ubiquitous presence across different cardiac regions and species, contributing to a comprehensive understanding of AF dynamics. The implications of these findings are profound, suggesting that targeting KACh channels might offer new therapeutic avenues for AF treatment, particularly in cases resistant to conventional approaches. By integrating genetic, cellular, and pharmacological perspectives, this manuscript offers a holistic view of the potential mechanisms and therapeutic targets in AF, making a significant contribution to the field of cardiac arrhythmia research.
Collapse
Affiliation(s)
- Vadim Mitrokhin
- Institute of Physiology, Federal State Autonomous Educational Institution of Higher Education “N.I. Pirogov, Russian National Research Medical University” Ministry of Health, 117997 Moscow, Russia; (V.M.); (V.K.); (S.S.); (O.K.); (A.R.); (A.Z.); (V.Z.); (A.K.)
| | - Nikola Hadzi-Petrushev
- Institute of Biology, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, 1000 Skopje, North Macedonia;
| | - Viktor Kazanski
- Institute of Physiology, Federal State Autonomous Educational Institution of Higher Education “N.I. Pirogov, Russian National Research Medical University” Ministry of Health, 117997 Moscow, Russia; (V.M.); (V.K.); (S.S.); (O.K.); (A.R.); (A.Z.); (V.Z.); (A.K.)
| | - Stanislav Schileyko
- Institute of Physiology, Federal State Autonomous Educational Institution of Higher Education “N.I. Pirogov, Russian National Research Medical University” Ministry of Health, 117997 Moscow, Russia; (V.M.); (V.K.); (S.S.); (O.K.); (A.R.); (A.Z.); (V.Z.); (A.K.)
| | - Olga Kamkina
- Institute of Physiology, Federal State Autonomous Educational Institution of Higher Education “N.I. Pirogov, Russian National Research Medical University” Ministry of Health, 117997 Moscow, Russia; (V.M.); (V.K.); (S.S.); (O.K.); (A.R.); (A.Z.); (V.Z.); (A.K.)
| | - Anastasija Rodina
- Institute of Physiology, Federal State Autonomous Educational Institution of Higher Education “N.I. Pirogov, Russian National Research Medical University” Ministry of Health, 117997 Moscow, Russia; (V.M.); (V.K.); (S.S.); (O.K.); (A.R.); (A.Z.); (V.Z.); (A.K.)
| | - Alexandra Zolotareva
- Institute of Physiology, Federal State Autonomous Educational Institution of Higher Education “N.I. Pirogov, Russian National Research Medical University” Ministry of Health, 117997 Moscow, Russia; (V.M.); (V.K.); (S.S.); (O.K.); (A.R.); (A.Z.); (V.Z.); (A.K.)
| | - Valentin Zolotarev
- Institute of Physiology, Federal State Autonomous Educational Institution of Higher Education “N.I. Pirogov, Russian National Research Medical University” Ministry of Health, 117997 Moscow, Russia; (V.M.); (V.K.); (S.S.); (O.K.); (A.R.); (A.Z.); (V.Z.); (A.K.)
| | - Andre Kamkin
- Institute of Physiology, Federal State Autonomous Educational Institution of Higher Education “N.I. Pirogov, Russian National Research Medical University” Ministry of Health, 117997 Moscow, Russia; (V.M.); (V.K.); (S.S.); (O.K.); (A.R.); (A.Z.); (V.Z.); (A.K.)
| | - Mitko Mladenov
- Institute of Physiology, Federal State Autonomous Educational Institution of Higher Education “N.I. Pirogov, Russian National Research Medical University” Ministry of Health, 117997 Moscow, Russia; (V.M.); (V.K.); (S.S.); (O.K.); (A.R.); (A.Z.); (V.Z.); (A.K.)
- Institute of Biology, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, 1000 Skopje, North Macedonia;
| |
Collapse
|
3
|
Nguyen H, Glaaser IW, Slesinger PA. Direct modulation of G protein-gated inwardly rectifying potassium (GIRK) channels. Front Physiol 2024; 15:1386645. [PMID: 38903913 PMCID: PMC11187414 DOI: 10.3389/fphys.2024.1386645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 04/08/2024] [Indexed: 06/22/2024] Open
Abstract
Ion channels play a pivotal role in regulating cellular excitability and signal transduction processes. Among the various ion channels, G-protein-coupled inwardly rectifying potassium (GIRK) channels serve as key mediators of neurotransmission and cellular responses to extracellular signals. GIRK channels are members of the larger family of inwardly-rectifying potassium (Kir) channels. Typically, GIRK channels are activated via the direct binding of G-protein βγ subunits upon the activation of G-protein-coupled receptors (GPCRs). GIRK channel activation requires the presence of the lipid signaling molecule, phosphatidylinositol 4,5-bisphosphate (PIP2). GIRK channels are also modulated by endogenous proteins and other molecules, including RGS proteins, cholesterol, and SNX27 as well as exogenous compounds, such as alcohol. In the last decade or so, several groups have developed novel drugs and small molecules, such as ML297, GAT1508 and GiGA1, that activate GIRK channels in a G-protein independent manner. Here, we aim to provide a comprehensive overview focusing on the direct modulation of GIRK channels by G-proteins, PIP2, cholesterol, and novel modulatory compounds. These studies offer valuable insights into the underlying molecular mechanisms of channel function, and have potential implications for both basic research and therapeutic development.
Collapse
Affiliation(s)
| | | | - Paul A. Slesinger
- Nash Family Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, United States
| |
Collapse
|
4
|
Liu C, Chen IS, Tateyama M, Kubo Y. Structural determinants of the direct inhibition of GIRK channels by Sigma-1 receptor antagonist. J Biol Chem 2024; 300:107219. [PMID: 38522516 PMCID: PMC11031820 DOI: 10.1016/j.jbc.2024.107219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 03/05/2024] [Accepted: 03/18/2024] [Indexed: 03/26/2024] Open
Abstract
G-protein-gated inward rectifier K+ (GIRK) channels play a critical role in the regulation of the excitability of cardiomyocytes and neurons and include GIRK1, GIRK2, GIRK3 and GIRK4 subfamily members. BD1047 dihydrobromide (BD1047) is one of the representative antagonists of the multifunctional Sigma-1 receptor (S1R). In the analysis of the effect of BD1047 on the regulation of Gi-coupled receptors by S1R using GIRK channel as an effector, we observed that BD1047, as well as BD1063, directly inhibited GIRK currents even in the absence of S1R and in a voltage-independent manner. Thus, we aimed to clarify the effect of BD1047 on GIRK channels and identify the structural determinants. By electrophysiological recordings in Xenopus oocytes, we observed that BD1047 directly inhibited GIRK channel currents, producing a much stronger inhibition of GIRK4 compared to GIRK2. It also inhibited ACh-induced native GIRK current in isolated rat atrial myocytes. Chimeric and mutagenesis studies of GIRK2 and GIRK4 combined with molecular docking analysis demonstrated the importance of Leu77 and Leu84 within the cytoplasmic, proximal N-terminal region and Glu147 within the pore-forming region of GIRK4 for inhibition by BD1047. The activator of GIRK channels, ivermectin, competed with BD1047 at Leu77 on GIRK4. This study provides us with a novel inhibitor of GIRK channels and information for developing pharmacological treatments for GIRK4-associated diseases.
Collapse
Affiliation(s)
- Chang Liu
- Division of Biophysics and Neurobiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan; Program of Physiological Sciences, Field of Life Science, Department of Advanced Studies, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Japan.
| | - I-Shan Chen
- Division of Biophysics and Neurobiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan; Program of Physiological Sciences, Field of Life Science, Department of Advanced Studies, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Japan; Faculty of Medicine, Department of Pharmacology, Wakayama Medical University, Wakayama, Japan
| | - Michihiro Tateyama
- Division of Biophysics and Neurobiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan; Program of Physiological Sciences, Field of Life Science, Department of Advanced Studies, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Japan
| | - Yoshihiro Kubo
- Division of Biophysics and Neurobiology, Department of Molecular and Cellular Physiology, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Japan; Program of Physiological Sciences, Field of Life Science, Department of Advanced Studies, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Japan.
| |
Collapse
|
5
|
Dolejší E, Janoušková A, Jakubík J. Muscarinic Receptors in Cardioprotection and Vascular Tone Regulation. Physiol Res 2024; 73:S389-S400. [PMID: 38634650 PMCID: PMC11412339 DOI: 10.33549/physiolres.935270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024] Open
Abstract
Muscarinic acetylcholine receptors are metabotropic G-protein coupled receptors. Muscarinic receptors in the cardiovascular system play a central role in its regulation. Particularly M2 receptors slow down the heart rate by reducing the impulse conductivity through the atrioventricular node. In general, activation of muscarinic receptors has sedative effects on the cardiovascular system, including vasodilation, negative chronotropic and inotropic effects on the heart, and cardioprotective effects, including antifibrillatory effects. First, we review the signaling of individual subtypes of muscarinic receptors and their involvement in the physiology and pathology of the cardiovascular system. Then we review age and disease-related changes in signaling via muscarinic receptors in the cardiovascular system. Finally, we review molecular mechanisms involved in cardioprotection mediated by muscarinic receptors leading to negative chronotropic and inotropic and antifibrillatory effects on heart and vasodilation, like activation of acetylcholine-gated inward-rectifier K+-currents and endothelium-dependent and -independent vasodilation. We relate this knowledge with well-established cardioprotective treatments by vagal stimulation and muscarinic agonists. It is well known that estrogen exerts cardioprotective effects against atherosclerosis and ischemia-reperfusion injury. Recently, some sex hormones and neurosteroids have been shown to allosterically modulate muscarinic receptors. Thus, we outline possible treatment by steroid-based positive allosteric modulators of acetylcholine as a novel pharmacotherapeutic tactic. Keywords: Muscarinic receptors, Muscarinic agonists, Allosteric modulation, Cardiovascular system, Cardioprotection, Steroids.
Collapse
Affiliation(s)
- E Dolejší
- Laboratory of Neurochemistry, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic.
| | | | | |
Collapse
|
6
|
Abstract
BACKGROUND Atrial fibrillation (AF) is by far the most common cardiac arrhythmia. In about 3% of individuals, AF develops as a primary disorder without any identifiable trigger (idiopathic or historically termed lone AF). In line with the emerging field of autoantibody-related cardiac arrhythmias, the objective of this study was to explore whether autoantibodies targeting cardiac ion channels can underlie unexplained AF. METHODS Peptide microarray was used to screen patient samples for autoantibodies. We compared patients with unexplained AF (n=37 pre-existent AF; n=14 incident AF on follow-up) to age- and sex-matched controls (n=37). Electrophysiological properties of the identified autoantibody were then tested in vitro with the patch clamp technique and in vivo with an experimental mouse model of immunization. RESULTS A common autoantibody response against Kir3.4 protein was detected in patients with AF and even before the development of clinically apparent AF. Kir3.4 protein forms a heterotetramer that underlies the cardiac acetylcholine-activated inwardly rectifying K+ current, IKACh. Functional studies on human induced pluripotent stem cell-derived atrial cardiomyocytes showed that anti-Kir3.4 IgG purified from patients with AF shortened action potentials and enhanced the constitutive form of IKACh, both key mediators of AF. To establish a causal relationship, we developed a mouse model of Kir3.4 autoimmunity. Electrophysiological study in Kir3.4-immunized mice showed that Kir3.4 autoantibodies significantly reduced atrial effective refractory period and predisposed animals to a 2.8-fold increased susceptibility to AF. CONCLUSIONS To our knowledge, this is the first report of an autoimmune pathogenesis of AF with direct evidence of Kir3.4 autoantibody-mediated AF.
Collapse
Affiliation(s)
- Ange Maguy
- Institute of Physiology, University of Bern, Switzerland (A.M.)
| | | | - Jean-Claude Tardif
- Montreal Heart Institute, Université de Montréal, Canada (J.-C.T., D.B.)
| | - David Busseuil
- Montreal Heart Institute, Université de Montréal, Canada (J.-C.T., D.B.)
| | - Jin Li
- Department of Cardiology, University Heart Center, University Hospital Zurich, University of Zurich, Switzerland (J.L.)
- Center for Translational and Experimental Cardiology, Department of Cardiology, University Hospital Zurich, University of Zurich, Schlieren, Switzerland (J.L.)
| |
Collapse
|
7
|
Meyer KM, Malhotra N, Kwak JS, El Refaey M. Relevance of KCNJ5 in Pathologies of Heart Disease. Int J Mol Sci 2023; 24:10849. [PMID: 37446026 PMCID: PMC10341679 DOI: 10.3390/ijms241310849] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/16/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023] Open
Abstract
Abnormalities in G-protein-gated inwardly rectifying potassium (GIRK) channels have been implicated in diseased states of the cardiovascular system; however, the role of GIRK4 (Kir3.4) in cardiac physiology and pathophysiology has yet to be completely understood. Within the heart, the KACh channel, consisting of two GIRK1 and two GIRK4 subunits, plays a major role in modulating the parasympathetic nervous system's influence on cardiac physiology. Being that GIRK4 is necessary for the functional KACh channel, KCNJ5, which encodes GIRK4, it presents as a therapeutic target for cardiovascular pathology. Human variants in KCNJ5 have been identified in familial hyperaldosteronism type III, long QT syndrome, atrial fibrillation, and sinus node dysfunction. Here, we explore the relevance of KCNJ5 in each of these diseases. Further, we address the limitations and complexities of discerning the role of KCNJ5 in cardiovascular pathophysiology, as identical human variants of KCNJ5 have been identified in several diseases with overlapping pathophysiology.
Collapse
Affiliation(s)
- Karisa M. Meyer
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University, Columbus, OH 43210, USA; (K.M.M.); (N.M.); (J.s.K.)
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Nipun Malhotra
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University, Columbus, OH 43210, USA; (K.M.M.); (N.M.); (J.s.K.)
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Jung seo Kwak
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University, Columbus, OH 43210, USA; (K.M.M.); (N.M.); (J.s.K.)
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| | - Mona El Refaey
- Department of Surgery, Division of Cardiac Surgery, The Ohio State University, Columbus, OH 43210, USA; (K.M.M.); (N.M.); (J.s.K.)
- The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA
| |
Collapse
|
8
|
Calvet C, Seebeck P. What to consider for ECG in mice-with special emphasis on telemetry. Mamm Genome 2023; 34:166-179. [PMID: 36749381 PMCID: PMC10290603 DOI: 10.1007/s00335-023-09977-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 01/16/2023] [Indexed: 02/08/2023]
Abstract
Genetically or surgically altered mice are commonly used as models of human cardiovascular diseases. Electrocardiography (ECG) is the gold standard to assess cardiac electrophysiology as well as to identify cardiac phenotypes and responses to pharmacological and surgical interventions. A variety of methods are used for mouse ECG acquisition under diverse conditions, making it difficult to compare different results. Non-invasive techniques allow only short-term data acquisition and are prone to stress or anesthesia related changes in cardiac activity. Telemetry offers continuous long-term acquisition of ECG data in conscious freely moving mice in their home cage environment. Additionally, it allows acquiring data 24/7 during different activities, can be combined with different challenges and most telemetry systems collect additional physiological parameters simultaneously. However, telemetry transmitters require surgical implantation, the equipment for data acquisition is relatively expensive and analysis of the vast number of ECG data is challenging and time-consuming. This review highlights the limits of non-invasive methods with respect to telemetry. In particular, primary screening using non-invasive methods can give a first hint; however, subtle cardiac phenotypes might be masked or compensated due to anesthesia and stress during these procedures. In addition, we detail the key differences between the mouse and human ECG. It is crucial to consider these differences when analyzing ECG data in order to properly translate the insights gained from murine models to human conditions.
Collapse
Affiliation(s)
- Charlotte Calvet
- Zurich Integrative Rodent Physiology (ZIRP), University of Zurich, Zurich, Switzerland
| | - Petra Seebeck
- Zurich Integrative Rodent Physiology (ZIRP), University of Zurich, Zurich, Switzerland
| |
Collapse
|
9
|
Peukert S, Gulgeze Efthymiou HB, Mo R, Peng Y, Ma F, Barbe G, Bebernitz G, Fridrich C, Buono C, Williams ET, Daniels T, Li L, Zhang X, Adachi Y, Abe M, Taggart AKP. Discovery of a brain-sparing GIRK1/4 inhibitor for pharmacological cardioversion of atrial fibrillation. Bioorg Med Chem Lett 2023; 85:129237. [PMID: 36924945 DOI: 10.1016/j.bmcl.2023.129237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 03/06/2023] [Accepted: 03/09/2023] [Indexed: 03/17/2023]
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia, and a significant risk factor for ischemic stroke and heart failure. Marketed anti-arrhythmic drugs can restore sinus rhythm, but with limited efficacy and significant toxicities, including potential to induce ventricular arrhythmia. Atrial-selective ion channel drugs are expected to restore and maintain sinus rhythm without risk of ventricular arrhythmia. One such atrial-selective channel target is GIRK1/4 (G-protein regulated inwardly rectifying potassium channel 1/4). Here we describe 14b, a potent GIRK1/4 inhibitor developed to cardiovert AF to sinus rhythm while minimizing central nervous system exposure - an issue with preceding GIRK1/4 clinical candidates.
Collapse
Affiliation(s)
- Stefan Peukert
- Novartis Institutes for Biomedical Research, 181 Massachusetts Avenue, Cambridge, MA 02139, USA.
| | | | - Ruowei Mo
- Novartis Institutes for Biomedical Research, 181 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Yunshan Peng
- Novartis Institutes for Biomedical Research, 181 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Fupeng Ma
- Novartis Institutes for Biomedical Research, 181 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Guillaume Barbe
- Novartis Institutes for Biomedical Research, 181 Massachusetts Avenue, Cambridge, MA 02139, USA
| | | | - Cary Fridrich
- Novartis Institutes for Biomedical Research, 181 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Chiara Buono
- Novartis Institutes for Biomedical Research, 181 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Eric T Williams
- Novartis Institutes for Biomedical Research, 181 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Thomas Daniels
- Novartis Institutes for Biomedical Research, 181 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Lisha Li
- Novartis Institutes for Biomedical Research, 181 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Xia Zhang
- Novartis Institutes for Biomedical Research, 181 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Yuichiro Adachi
- Novartis Institutes for Biomedical Research, 181 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Mie Abe
- Former Novartis Employee, USA
| | - Andrew K P Taggart
- Novartis Institutes for Biomedical Research, 181 Massachusetts Avenue, Cambridge, MA 02139, USA
| |
Collapse
|
10
|
Manoj P, Kim JA, Kim S, Li T, Sewani M, Chelu MG, Li N. Sinus node dysfunction: current understanding and future directions. Am J Physiol Heart Circ Physiol 2023; 324:H259-H278. [PMID: 36563014 PMCID: PMC9886352 DOI: 10.1152/ajpheart.00618.2022] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/20/2022] [Accepted: 12/21/2022] [Indexed: 12/24/2022]
Abstract
The sinoatrial node (SAN) is the primary pacemaker of the heart. Normal SAN function is crucial in maintaining proper cardiac rhythm and contraction. Sinus node dysfunction (SND) is due to abnormalities within the SAN, which can affect the heartbeat frequency, regularity, and the propagation of electrical pulses through the cardiac conduction system. As a result, SND often increases the risk of cardiac arrhythmias. SND is most commonly seen as a disease of the elderly given the role of degenerative fibrosis as well as other age-dependent changes in its pathogenesis. Despite the prevalence of SND, current treatment is limited to pacemaker implantation, which is associated with substantial medical costs and complications. Emerging evidence has identified various genetic abnormalities that can cause SND, shedding light on the molecular underpinnings of SND. Identification of these molecular mechanisms and pathways implicated in the pathogenesis of SND is hoped to identify novel therapeutic targets for the development of more effective therapies for this disease. In this review article, we examine the anatomy of the SAN and the pathophysiology and epidemiology of SND. We then discuss in detail the most common genetic mutations correlated with SND and provide our perspectives on future research and therapeutic opportunities in this field.
Collapse
Affiliation(s)
- Pavan Manoj
- School of Public Health, Texas A&M University, College Station, Texas
| | - Jitae A Kim
- Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Stephanie Kim
- Department of BioSciences, Rice University, Houston, Texas
| | - Tingting Li
- Section of Cardiovascular Research, Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Maham Sewani
- Department of BioSciences, Rice University, Houston, Texas
| | - Mihail G Chelu
- Division of Cardiology, Department of Medicine, Baylor College of Medicine, Houston, Texas
| | - Na Li
- Section of Cardiovascular Research, Department of Medicine, Baylor College of Medicine, Houston, Texas
| |
Collapse
|
11
|
Fan W, Sun X, Yang C, Wan J, Luo H, Liao B. Pacemaker activity and ion channels in the sinoatrial node cells: MicroRNAs and arrhythmia. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2023; 177:151-167. [PMID: 36450332 DOI: 10.1016/j.pbiomolbio.2022.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 11/13/2022] [Accepted: 11/25/2022] [Indexed: 11/29/2022]
Abstract
The primary pacemaking activity of the heart is determined by a spontaneous action potential (AP) within sinoatrial node (SAN) cells. This unique AP generation relies on two mechanisms: membrane clocks and calcium clocks. Nonhomologous arrhythmias are caused by several functional and structural changes in the myocardium. MicroRNAs (miRNAs) are essential regulators of gene expression in cardiomyocytes. These miRNAs play a vital role in regulating the stability of cardiac conduction and in the remodeling process that leads to arrhythmias. Although it remains unclear how miRNAs regulate the expression and function of ion channels in the heart, these regulatory mechanisms may support the development of emerging therapies. This study discusses the spread and generation of AP in the SAN as well as the regulation of miRNAs and individual ion channels. Arrhythmogenicity studies on ion channels will provide a research basis for miRNA modulation as a new therapeutic target.
Collapse
Affiliation(s)
- Wei Fan
- Department of Cardiovascular Surgery, Affiliated Hospital of Southwest Medical University, 25 Taiping Street, Jiangyang District, Luzhou, Sichuan Province, 646000, China
| | - Xuemei Sun
- Department of Pharmacy, Affiliated Hospital of Southwest Medical University, 25 Taiping Street, Jiangyang District, Luzhou, Sichuan Province, 646000, China
| | - Chao Yang
- Department of Cardiovascular Surgery, Affiliated Hospital of Southwest Medical University, 25 Taiping Street, Jiangyang District, Luzhou, Sichuan Province, 646000, China
| | - Juyi Wan
- Department of Cardiovascular Surgery, Affiliated Hospital of Southwest Medical University, 25 Taiping Street, Jiangyang District, Luzhou, Sichuan Province, 646000, China.
| | - Hongli Luo
- Department of Pharmacy, Affiliated Hospital of Southwest Medical University, 25 Taiping Street, Jiangyang District, Luzhou, Sichuan Province, 646000, China.
| | - Bin Liao
- Department of Cardiovascular Surgery, Affiliated Hospital of Southwest Medical University, 25 Taiping Street, Jiangyang District, Luzhou, Sichuan Province, 646000, China.
| |
Collapse
|
12
|
Campos-Ríos A, Rueda-Ruzafa L, Lamas JA. The Relevance of GIRK Channels in Heart Function. MEMBRANES 2022; 12:1119. [PMID: 36363674 PMCID: PMC9698958 DOI: 10.3390/membranes12111119] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/06/2022] [Accepted: 11/07/2022] [Indexed: 06/16/2023]
Abstract
Among the large number of potassium-channel families implicated in the control of neuronal excitability, G-protein-gated inwardly rectifying potassium channels (GIRK/Kir3) have been found to be a main factor in heart control. These channels are activated following the modulation of G-protein-coupled receptors and, although they have been implicated in different neurological diseases in both human and animal studies of the central nervous system, the therapeutic potential of different subtypes of these channel families in cardiac conditions has remained untapped. As they have emerged as a promising potential tool to treat a variety of conditions that disrupt neuronal homeostasis, many studies have started to focus on these channels as mediators of cardiac dynamics, thus leading to research into their implication in cardiovascular conditions. Our aim is to review the latest advances in GIRK modulation in the heart and their role in the cardiovascular system.
Collapse
Affiliation(s)
- Ana Campos-Ríos
- CINBIO, Laboratory of Neuroscience, University of Vigo, 36310 Vigo, Spain
- Laboratory of Neuroscience, Galicia Sur Health Research Institute (IISGS), 15706 Vigo, Spain
| | - Lola Rueda-Ruzafa
- Department of Nursing Science, Physiotherapy and Medicine, Faculty of Health Sciences, University of Almeria, 04120 Almeria, Spain
| | - José Antonio Lamas
- CINBIO, Laboratory of Neuroscience, University of Vigo, 36310 Vigo, Spain
- Laboratory of Neuroscience, Galicia Sur Health Research Institute (IISGS), 15706 Vigo, Spain
| |
Collapse
|
13
|
Sung DJ, Jeon YK, Choi J, Kim B, Golpasandi S, Park SW, Oh SB, Bae YM. Protective effect of low-intensity treadmill exercise against acetylcholine-calcium chloride-induced atrial fibrillation in mice. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2022; 26:313-323. [PMID: 36039732 PMCID: PMC9437371 DOI: 10.4196/kjpp.2022.26.5.313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 06/15/2023]
Abstract
Atrial fibrillation (AF) is the most common supraventricular arrhythmia, and it corresponds highly with exercise intensity. Here, we induced AF in mice using acetylcholine (ACh)-CaCl2 for 7 days and aimed to determine the appropriate exercise intensity (no, low, moderate, high) to protect against AF by running the mice at different intensities for 4 weeks before the AF induction by ACh-CaCl2. We examined the AF-induced atrial remodeling using electrocardiogram, patch-clamp, and immunohistochemistry. After the AF induction, heart rate, % increase of heart rate, and heart weight/body weight ratio were significantly higher in all the four AF groups than in the normal control; highest in the high-ex AF and lowest in the low-ex (lower than the no-ex AF), which indicates that low-ex treated the AF. Consistent with these changes, G protein-gated inwardly rectifying K+ currents, which were induced by ACh, increased in an exercise intensity-dependent manner and were lower in the low-ex AF than the no-ex AF. The peak level of Ca2+ current (at 0 mV) increased also in an exercise intensity-dependent manner and the inactivation time constants were shorter in all AF groups except for the low-ex AF group, in which the time constant was similar to that of the control. Finally, action potential duration was shorter in all the four AF groups than in the normal control; shortest in the high-ex AF and longest in the low-ex AF. Taken together, we conclude that low-intensity exercise protects the heart from AF, whereas high-intensity exercise might exacerbate AF.
Collapse
Affiliation(s)
- Dong-Jun Sung
- Department of Sport and Health Studies, College of Biomedical and Health Science, Konkuk University, Chungju 27478, Korea
- Sports Convergence Institute, Chungju 27478, Korea
- Center for Metabolic Diseases, Konkuk University, Chungju 27478, Korea
| | - Yong-Kyun Jeon
- Department of Physical Education at the Graduate School of Education, Dankook University, Yongin 16890, Korea
| | - Jaeil Choi
- Department of Physical Education at the Graduate School of Education, Dankook University, Yongin 16890, Korea
| | - Bokyung Kim
- Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, Chungju 27478, Korea
| | - Shadi Golpasandi
- Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, Chungju 27478, Korea
| | - Sang Woong Park
- Department of Emergency Medical Services, College of Health Sciences, Eulji University, Seongam 13135, Korea
| | - Seung-Bum Oh
- Department of Sport and Health Studies, College of Biomedical and Health Science, Konkuk University, Chungju 27478, Korea
| | - Young Min Bae
- Department of Physiology, KU Open Innovation Center, Research Institute of Medical Science, Konkuk University School of Medicine, Chungju 27478, Korea
| |
Collapse
|
14
|
MT9, a natural peptide from black mamba venom antagonizes the muscarinic type 2 receptor and reverses the M2R-agonist-induced relaxation in rat and human arteries. Biomed Pharmacother 2022; 150:113094. [PMID: 35658242 DOI: 10.1016/j.biopha.2022.113094] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 04/25/2022] [Accepted: 05/04/2022] [Indexed: 11/20/2022] Open
Abstract
All five muscarinic receptors have important physiological roles. The endothelial M2 and M3 subtypes regulate arterial tone through direct coupling to Gq or Gi/o proteins. Yet, we lack selective pharmacological drugs to assess the respective contribution of muscarinic receptors to a given function. We used mamba snake venoms to identify a selective M2R ligand to investigate its contribution to arterial contractions. Using a bio-guided screening binding assay, we isolated MT9 from the black mamba venom, a three-finger toxin active on the M2R subtype. After sequencing and chemical synthesis of MT9, we characterized its structure by X-ray diffraction and determined its pharmacological characteristics by binding assays, functional tests, and ex vivo experiments on rat and human arteries. Although MT9 belongs to the three-finger fold toxins family, it is phylogenetically apart from the previously discovered muscarinic toxins, suggesting that two groups of peptides evolved independently and in a convergent way to target muscarinic receptors. The affinity of MT9 for the M2R is 100 times stronger than that for the four other muscarinic receptors. It also antagonizes the M2R/Gi pathways in cell-based assays. MT9 acts as a non-competitive antagonist against acetylcholine or arecaine, with low nM potency, for the activation of isolated rat mesenteric arteries. These results were confirmed on human internal mammary arteries. In conclusion, MT9 is the first fully characterized M2R-specific natural toxin. It should provide a tool for further understanding of the effect of M2R in various arteries and may position itself as a new drug candidate in cardio-vascular diseases.
Collapse
|
15
|
Fu F, Pietropaolo M, Cui L, Pandit S, Li W, Tarnavski O, Shetty SS, Liu J, Lussier JM, Murakami Y, Grewal PK, Deyneko G, Turner GM, Taggart AKP, Waters MG, Coughlin S, Adachi Y. Lack of authentic atrial fibrillation in commonly used murine atrial fibrillation models. PLoS One 2022; 17:e0256512. [PMID: 34995278 PMCID: PMC8741011 DOI: 10.1371/journal.pone.0256512] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Accepted: 12/23/2021] [Indexed: 12/19/2022] Open
Abstract
The mouse is a useful preclinical species for evaluating disease etiology due to the availability of a wide variety of genetically modified strains and the ability to perform disease-modifying manipulations. In order to establish an atrial filtration (AF) model in our laboratory, we profiled several commonly used murine AF models. We initially evaluated a pharmacological model of acute carbachol (CCh) treatment plus atrial burst pacing in C57BL/6 mice. In an effort to observe micro-reentrant circuits indicative of authentic AF, we employed optical mapping imaging in isolated mouse hearts. While CCh reduced atrial refractoriness and increased atrial tachyarrhythmia vulnerability, the left atrial (LA) excitation patterns were rather regular without reentrant circuits or wavelets. Therefore, the atrial tachyarrhythmia resembled high frequency atrial flutter, not typical AF per se. We next examined both a chronic angiotensin II (Ang II) infusion model and the surgical model of transverse aortic constriction (TAC), which have both been reported to induce atrial and ventricular structural changes that serve as a substrates for micro-reentrant AF. Although we observed some extent of atrial remodeling such as fibrosis or enlarged LA diameter, burst pacing-induced atrial tachyarrhythmia vulnerability did not differ from control mice in either model. This again suggested that an AF-like pathophysiology is difficult to demonstrate in the mouse. To continue searching for a valid murine AF model, we studied mice with a cardiac-specific deficiency (KO) in liver kinase B1 (Cardiac-LKB1), which has been reported to exhibit spontaneous AF. Indeed, the electrocardiograms (ECG) of conscious Cardiac-LKB1 KO mice exhibited no P waves and had irregular RR intervals, which are characteristics of AF. Histological evaluation of Cardiac-LKB1 KO mice revealed dilated and fibrotic atria, again consistent with AF. However, atrial electrograms and optical mapping revealed that electrical activity was limited to the sino-atrial node area with no electrical conduction into the atrial myocardium beyond. Thus, Cardiac-LKB1 KO mice have severe atrial myopathy or atrial standstill, but not AF. In summary, the atrial tachyarrhythmias we observed in the four murine models were distinct from typical human AF, which often exhibits micro- or macro-reentrant atrial circuits. Our results suggest that the four murine AF models we examined may not reflect human AF well, and raise a cautionary note for use of those murine models to study AF.
Collapse
Affiliation(s)
- Fumin Fu
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Michael Pietropaolo
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Lei Cui
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Shilpa Pandit
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Weiyan Li
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Oleg Tarnavski
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Suraj S. Shetty
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Jing Liu
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Jennifer M. Lussier
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Yutaka Murakami
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Prabhjit K. Grewal
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Galina Deyneko
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Gordon M. Turner
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Andrew K. P. Taggart
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - M. Gerard Waters
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Shaun Coughlin
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
| | - Yuichiro Adachi
- Cardiovascular and Metabolic Diseases, Novartis Institutes for BioMedical Research, Inc. Cambridge, Massachusetts, United State of America
- * E-mail:
| |
Collapse
|
16
|
Linz B, Thostrup AH, Saljic A, Rombouts K, Hertel JN, Hohl M, Milnes J, Tfelt-Hansen J, Linz D, Jespersen T. Pharmacological inhibition of acetylcholine-regulated potassium current (IK,ACh) prevents atrial arrhythmogenic changes in a rat model of repetitive obstructive respiratory events. Heart Rhythm O2 2021; 3:97-104. [PMID: 35243441 PMCID: PMC8859790 DOI: 10.1016/j.hroo.2021.11.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Background In obstructive sleep apnea (OSA), intermittent hypoxemia and intrathoracic pressure fluctuations may increase atrial fibrillation (AF) susceptibility by cholinergic activation. Objective To investigate short-term atrial electrophysiological consequences of obstructive respiratory events, simulated by intermittent negative upper airway pressure (INAP), and the role of atrial acetylcholine-regulated potassium current (IK,ACh) activated by the M2 receptor. Methods In sedated (2% isoflurane), spontaneously breathing rats, INAP was applied noninvasively by a negative pressure device for 1 minute, followed by a resting period of 4 minutes. INAP was applied repeatedly throughout 70 minutes, followed by a 2-hour recovery period. Atrial effective refractory period (AERP) and AF inducibility were determined throughout the protocol. To study INAP-induced IK,ACh activation, protein levels of protein kinase C (PKCƐ) were determined in membrane and cytosolic fractions of left atrial (LA) tissue by Western blotting. Moreover, an IK,ACh inhibitor (XAF-1407: 1 mg/kg) and a muscarinic receptor inhibitor (atropine: 1 μg/kg) were investigated. Results In vehicle-treated rats, repetitive INAP shortened AERP (37 ± 3 ms vs baseline 44 ± 3 ms; P = .001) and increased LA membrane PKCƐ content relative to cytosolic levels. Upon INAP recovery, ratio of PKCƐ membrane to cytosol content normalized and INAP-induced AERP shortening reversed. Both XAF-1407 and atropine increased baseline AERP (control vs XAF-1407: 61 ± 4 ms; P > .001 and control vs atropine: 58 ± 3 ms; P = .011) and abolished INAP-associated AERP shortening. Conclusion Short-term simulated OSA is associated with a progressive, but transient, AERP shortening and a PKCƐ translocation to LA membrane. Pharmacological IK,ACh and muscarinic receptor inhibition prevented transient INAP-induced AERP shortening, suggesting an involvement of IK,ACh in the transient arrhythmogenic AF substrate in OSA.
Collapse
|
17
|
Jost N, Christ T, Magyar J. New Strategies for the Treatment of Atrial Fibrillation. Pharmaceuticals (Basel) 2021; 14:ph14090926. [PMID: 34577626 PMCID: PMC8466466 DOI: 10.3390/ph14090926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 09/07/2021] [Accepted: 09/08/2021] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia in the clinical practice. It significantly contributes to the morbidity and mortality of the elderly population. Over the past 25-30 years intense effort in basic research has advanced the understanding of the relationship between the pathophysiology of AF and atrial remodelling. Nowadays it is clear that the various forms of atrial remodelling (electrical, contractile and structural) play crucial role in initiating and maintaining the persistent and permanent types of AF. Unlike in ventricular fibrillation, in AF rapid ectopic firing originating from pulmonary veins and re-entry mechanism may induce and maintain (due to atrial remodelling) this complex cardiac arrhythmia. The present review presents and discusses in detail the latest knowledge on the role of remodelling in AF. Special attention is paid to novel concepts and pharmacological targets presumably relevant to the drug treatment of atrial fibrillation.
Collapse
Affiliation(s)
- Norbert Jost
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, 6725 Szeged, Hungary
- Department of Pharmacology and Pharmacotherapy, Interdisciplinary Excellence Centre, University of Szeged, 6725 Szeged, Hungary
- ELKH-SZTE Research Group for Cardiovascular Pharmacology, Eötvös Loránd Research Network, 6725 Szeged, Hungary
- Correspondence:
| | - Torsten Christ
- Institute of Experimental Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany;
- DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - János Magyar
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary;
- Department of Sport Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| |
Collapse
|
18
|
Anderson A, Vo BN, de Velasco EMF, Hopkins CR, Weaver CD, Wickman K. Characterization of VU0468554, a New Selective Inhibitor of Cardiac G Protein-Gated Inwardly Rectifying K + Channels. Mol Pharmacol 2021; 100:540-547. [PMID: 34503975 DOI: 10.1124/molpharm.121.000311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 09/01/2021] [Indexed: 11/22/2022] Open
Abstract
G protein-gated inwardly rectifying K+ (GIRK) channels are critical mediators of excitability in the heart and brain. Enhanced GIRK-channel activity has been implicated in the pathogenesis of supraventricular arrhythmias, including atrial fibrillation. The lack of selective pharmacological tools has impeded efforts to investigate the therapeutic potential of cardiac GIRK-channel interventions in arrhythmias. Here, we characterize a recently identified GIRK-channel inhibitor, VU0468554. Using whole-cell electrophysiological approaches and primary cultures of sinoatrial nodal cells and hippocampal neurons, we show that VU0468554 more effectively inhibits the cardiac GIRK channel than the neuronal GIRK channel. Concentration-response experiments suggest that VU0468554 inhibits Gβγ-activated GIRK channels in noncompetitive and potentially uncompetitive fashion. In contrast, VU0468554 competitively inhibits GIRK-channel activation by ML297, a GIRK-channel activator containing the same chemical scaffold as VU0468554. In the isolated heart model, VU0468554 partially reversed carbachol-induced bradycardia in hearts from wild-type mice but not Girk4-/- mice. Collectively, these data suggest that VU0468554 represents a promising new pharmacological tool for targeting cardiac GIRK channels with therapeutic implications for relevant cardiac arrhythmias. SIGNIFICANCE STATEMENT: Although cardiac GIRK-channel inhibition shows promise for the treatment of supraventricular arrhythmias, the absence of subtype-selective channel inhibitors has hindered exploration into this therapeutic strategy. This study utilizes whole-cell patch-clamp electrophysiology to characterize the new GIRK-channel inhibitor VU0468554 in human embryonic kidney 293T cells and primary cultures. We report that VU0468554 exhibits a favorable pharmacodynamic profile for cardiac over neuronal GIRK channels and partially reverses GIRK-mediated bradycardia in the isolated mouse heart model.
Collapse
Affiliation(s)
- Allison Anderson
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Baovi N Vo
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Ezequiel Marron Fernandez de Velasco
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Corey R Hopkins
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - C David Weaver
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| | - Kevin Wickman
- Graduate Program in Pharmacology (A.A., B.N.V.) and Department of Pharmacology (E.M.F.d.V., K.W.), University of Minnesota, Minneapolis, Minnesota; Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.); and Departments of Pharmacology and Chemistry and Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee (C.D.W.)
| |
Collapse
|
19
|
Kir Channel Molecular Physiology, Pharmacology, and Therapeutic Implications. Handb Exp Pharmacol 2021; 267:277-356. [PMID: 34345939 DOI: 10.1007/164_2021_501] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
For the past two decades several scholarly reviews have appeared on the inwardly rectifying potassium (Kir) channels. We would like to highlight two efforts in particular, which have provided comprehensive reviews of the literature up to 2010 (Hibino et al., Physiol Rev 90(1):291-366, 2010; Stanfield et al., Rev Physiol Biochem Pharmacol 145:47-179, 2002). In the past decade, great insights into the 3-D atomic resolution structures of Kir channels have begun to provide the molecular basis for their functional properties. More recently, computational studies are beginning to close the time domain gap between in silico dynamic and patch-clamp functional studies. The pharmacology of these channels has also been expanding and the dynamic structural studies provide hope that we are heading toward successful structure-based drug design for this family of K+ channels. In the present review we focus on placing the physiology and pharmacology of this K+ channel family in the context of atomic resolution structures and in providing a glimpse of the promising future of therapeutic opportunities.
Collapse
|
20
|
Odening KE, Gomez AM, Dobrev D, Fabritz L, Heinzel FR, Mangoni ME, Molina CE, Sacconi L, Smith G, Stengl M, Thomas D, Zaza A, Remme CA, Heijman J. ESC working group on cardiac cellular electrophysiology position paper: relevance, opportunities, and limitations of experimental models for cardiac electrophysiology research. Europace 2021; 23:1795-1814. [PMID: 34313298 DOI: 10.1093/europace/euab142] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 05/19/2021] [Indexed: 12/19/2022] Open
Abstract
Cardiac arrhythmias are a major cause of death and disability. A large number of experimental cell and animal models have been developed to study arrhythmogenic diseases. These models have provided important insights into the underlying arrhythmia mechanisms and translational options for their therapeutic management. This position paper from the ESC Working Group on Cardiac Cellular Electrophysiology provides an overview of (i) currently available in vitro, ex vivo, and in vivo electrophysiological research methodologies, (ii) the most commonly used experimental (cellular and animal) models for cardiac arrhythmias including relevant species differences, (iii) the use of human cardiac tissue, induced pluripotent stem cell (hiPSC)-derived and in silico models to study cardiac arrhythmias, and (iv) the availability, relevance, limitations, and opportunities of these cellular and animal models to recapitulate specific acquired and inherited arrhythmogenic diseases, including atrial fibrillation, heart failure, cardiomyopathy, myocarditis, sinus node, and conduction disorders and channelopathies. By promoting a better understanding of these models and their limitations, this position paper aims to improve the quality of basic research in cardiac electrophysiology, with the ultimate goal to facilitate the clinical translation and application of basic electrophysiological research findings on arrhythmia mechanisms and therapies.
Collapse
Affiliation(s)
- Katja E Odening
- Translational Cardiology, Department of Cardiology, Inselspital, Bern University Hospital, Bern, Switzerland.,Institute of Physiology, University of Bern, Bern, Switzerland
| | - Ana-Maria Gomez
- Signaling and cardiovascular pathophysiology-UMR-S 1180, Inserm, Université Paris-Saclay, 92296 Châtenay-Malabry, France
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | - Larissa Fabritz
- Institute of Cardiovascular Sciences, University of Birmingham, Birmingham, UK.,Department of Cardiology, University Hospital Birmingham NHS Trust, Birmingham, UK
| | - Frank R Heinzel
- Department of Internal Medicine and Cardiology, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Berlin, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site, Berlin, Germany
| | - Matteo E Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Cristina E Molina
- Institute of Experimental Cardiovascular Research, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.,German Centre for Cardiovascular Research (DZHK), Partner Site, Hamburg/Kiel/Lübeck, Germany
| | - Leonardo Sacconi
- National Institute of Optics and European Laboratory for Non Linear Spectroscopy, Italy.,Institute for Experimental Cardiovascular Medicine, University Freiburg, Germany
| | - Godfrey Smith
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK
| | - Milan Stengl
- Department of Physiology, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czech Republic
| | - Dierk Thomas
- Department of Cardiology, University Hospital Heidelberg, Heidelberg, Germany; Heidelberg Center for Heart Rhythm Disorders (HCR), University Hospital Heidelberg, Heidelberg, Germany.,German Centre for Cardiovascular Research (DZHK), Partner Site, Heidelberg/Mannheim, Germany
| | - Antonio Zaza
- Department of Biotechnology and Bioscience, University of Milano-Bicocca, Milano, Italy
| | - Carol Ann Remme
- Department of Experimental Cardiology, Amsterdam UMC, location AMC, Amsterdam, The Netherlands
| | - Jordi Heijman
- Department of Cardiology, CARIM School for Cardiovascular Diseases, Maastricht University, Maastricht, The Netherlands
| |
Collapse
|
21
|
Enhanced atrial internal-external neural remodeling facilitates atrial fibrillation in the chronic obstructive sleep apnea model. PLoS One 2021; 16:e0247308. [PMID: 33606818 PMCID: PMC7895341 DOI: 10.1371/journal.pone.0247308] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 02/04/2021] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Autonomic imbalance plays a crucial role in obstructive sleep apnea (OSA) associated atrial fibrillation (AF). Here, we investigated the potential neural mechanism of AF induced by OSA. METHODS Ten dogs were divided into control group (n = 5) and OSA group (n = 5). The chronic OSA model was established by repeat apnea-ventilation cycles for 4 hours a day for 12 weeks. During the process of model establishment, arterial blood gases, atrial effective refractory period (AERP), AF inducibility, normalized low-frequency power (LFnu), normalized high-frequency power (HFnu), and LFnu/ HFnu were evaluated at baseline, 4th week, 8th week, and 12th week. Nerve activities of left stellate ganglion (LSG) and left vagal nerve(LVN) were recorded. Tyrosine hydroxylase(TH), choline acetyltransferase(CHAT), PGP9.5, nerve growth factor(NGF), and c-Fos were detected in the left atrium, LSG, and LVN by immunohistochemistry and western blot. Moreover, high-frequency stimulations of LSG and LVN were conducted to observe the AF inducibility. RESULTS Compared with the control group, the OSA group showed significantly enhanced neural activity of the LSG, increased AF inducibility, and shortened AERP. LFnu and LFnu/HFnu were markedly increased in the OSA group, while no significant difference in HFnu was observed. TH-positive and PGP9.5-positive nerve densities were significantly increased in the LSG and left atrium. Additionally, the protein levels of NGF, c-Fos, and PGP9.5 were upregulated both in the LSG and left atrium. AF inducibility was markedly increased under LSG stimulation without a stimulus threshold change in the OSA group. CONCLUSIONS OSA significantly enhanced LSG and left atrial neural remodeling, and hyperactivity of LSG may accelerate left atrial neural remodeling to increase AF inducibility.
Collapse
|
22
|
Exercise and Athletic Activity in Atrial Fibrillation. Card Electrophysiol Clin 2021; 13:173-182. [PMID: 33516395 DOI: 10.1016/j.ccep.2020.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Moderate-intensity exercise improves cardiovascular outcomes. However, mounting clinical evidence demonstrates that long-term, high-intensity endurance training predisposes male and veteran athletes to an increased risk of atrial fibrillation (AF), a risk that is not observed across both genders. Although increased mortality associated with AF in the general population is not shared by athletes, clinically significant morbidities exist (eg, reduced exercise capacity, athletic performance, and quality of life). Additional research is needed to fill current gaps in knowledge pertaining to the natural history, pathophysiologic mechanisms, and management strategies of AF in the athlete.
Collapse
|
23
|
Zhang H, Zhang S, Wang W, Wang K, Shen W. A Mathematical Model of the Mouse Atrial Myocyte With Inter-Atrial Electrophysiological Heterogeneity. Front Physiol 2020; 11:972. [PMID: 32848887 PMCID: PMC7425199 DOI: 10.3389/fphys.2020.00972] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 07/16/2020] [Indexed: 12/20/2022] Open
Abstract
Biophysically detailed mathematical models of cardiac electrophysiology provide an alternative to experimental approaches for investigating possible ionic mechanisms underlying the genesis of electrical action potentials and their propagation through the heart. The aim of this study was to develop a biophysically detailed mathematical model of the action potentials of mouse atrial myocytes, a popular experimental model for elucidating molecular and cellular mechanisms of arrhythmogenesis. Based on experimental data from isolated mouse atrial cardiomyocytes, a set of mathematical equations for describing the biophysical properties of membrane ion channel currents, intracellular Ca2+ handling, and Ca2+-calmodulin activated protein kinase II and β-adrenergic signaling pathways were developed. Wherever possible, membrane ion channel currents were modeled using Markov chain formalisms, allowing detailed representation of channel kinetics. The model also considered heterogeneous electrophysiological properties between the left and the right atrial cardiomyocytes. The developed model was validated by its ability to reproduce the characteristics of action potentials and Ca2+ transients, matching quantitatively to experimental data. Using the model, the functional roles of four K+ channel currents in atrial action potential were evaluated by channel block simulations, results of which were quantitatively in agreement with existent experimental data. To conclude, this newly developed model of mouse atrial cardiomyocytes provides a powerful tool for investigating possible ion channel mechanisms of atrial electrical activity at the cellular level and can be further used to investigate mechanisms underlying atrial arrhythmogenesis.
Collapse
Affiliation(s)
- Henggui Zhang
- Department of Physics and Astronomy, Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom.,Peng Cheng Laboratory, Shenzhen, China
| | - Shanzhuo Zhang
- Department of Physics and Astronomy, Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom.,School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Wei Wang
- Department of Physics and Astronomy, Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom.,Peng Cheng Laboratory, Shenzhen, China.,Shenzhen Key Laboratory of Visual Object Detection and Recognition, Harbin Institute of Technology, Shenzhen, China
| | - Kuanquan Wang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
| | - Weijian Shen
- Department of Physics and Astronomy, Biological Physics Group, School of Physics & Astronomy, The University of Manchester, Manchester, United Kingdom
| |
Collapse
|
24
|
Fenner MF, Carstensen H, Dalgas Nissen S, Melis Hesselkilde E, Scott Lunddahl C, Adler Hess Jensen M, Loft-Andersen AV, Sattler SM, Platonov P, El-Haou S, Jackson C, Tang R, Kirby R, Ford J, Schotten U, Milnes J, Svane Sørensen U, Jespersen T, Buhl R. Effect of selective I K,ACh inhibition by XAF-1407 in an equine model of tachypacing-induced persistent atrial fibrillation. Br J Pharmacol 2020; 177:3778-3794. [PMID: 32436234 DOI: 10.1111/bph.15100] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 03/20/2020] [Accepted: 05/01/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND AND PURPOSE Inhibition of the G-protein gated ACh-activated inward rectifier potassium current, IK,ACh may be an effective atrial selective treatment strategy for atrial fibrillation (AF). Therefore, the anti-arrhythmic and electrophysiological properties of a novel putatively potent and highly specific IK,ACh inhibitor, XAF-1407 (3-methyl-1-[5-phenyl-4-[4-(2-pyrrolidin-1-ylethoxymethyl)-1-piperidyl]thieno[2,3-d]pyrimidin-6-yl]azetidin-3-ol), were characterised for the first time in vitro and investigated in horses with persistent AF. EXPERIMENTAL APPROACH The pharmacological ion channel profile of XAF-1407 was investigated using cell lines expressing relevant ion channels. In addition, eleven horses were implanted with implantable cardioverter defibrillators enabling atrial tachypacing into self-sustained AF. The electrophysiological effects of XAF-1407 were investigated after serial cardioversions over a period of 1 month. Cardioversion success, drug-induced changes of atrial tissue refractoriness, and ventricular electrophysiology were assessed at baseline (day 0) and days 3, 5, 11, 17, and 29 after AF induction. KEY RESULTS XAF-1407 potently and selectively inhibited Kir 3.1/3.4 and Kir 3.4/3.4, underlying the IK,ACh current. XAF-1407 treatment in horses prolonged atrial effective refractory period as well as decreased atrial fibrillatory rate significantly (~20%) and successfully cardioverted AF, although with a decreasing efficacy over time. XAF-1407 shortened atrioventricular-nodal refractoriness, without effect on QRS duration. QTc prolongation (4%) within 15 min of drug infusion was observed, however, without any evidence of ventricular arrhythmia. CONCLUSION AND IMPLICATIONS XAF-1407 efficiently cardioverted sustained tachypacing-induced AF of short duration in horses without notable side effects. This supports IK,ACh inhibition as a potentially safe treatment of paroxysmal AF in horses, suggesting potential clinical value for other species including humans.
Collapse
Affiliation(s)
- Merle Friederike Fenner
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Helena Carstensen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Sarah Dalgas Nissen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Eva Melis Hesselkilde
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Christine Scott Lunddahl
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Maja Adler Hess Jensen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Ameli Victoria Loft-Andersen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Stefan Michael Sattler
- Department of Cardiology, The Heart Centre, Copenhagen University Hospital, Copenhagen, Denmark.,Department of Medicine I, University Hospital Munich, Campus Grosshadern, Ludwig-Maximilians University Munich (LMU), Munich, Germany
| | - Pyotr Platonov
- Arrhythmia Clinic, Skåne University Hospital and Department of Cardiology, Clinical Sciences, Lund University, Lund, Sweden
| | | | | | | | | | | | - Ulrich Schotten
- Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands
| | | | | | - Thomas Jespersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rikke Buhl
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| |
Collapse
|
25
|
Anderson A, Masuho I, Marron Fernandez de Velasco E, Nakano A, Birnbaumer L, Martemyanov KA, Wickman K. GPCR-dependent biasing of GIRK channel signaling dynamics by RGS6 in mouse sinoatrial nodal cells. Proc Natl Acad Sci U S A 2020; 117:14522-14531. [PMID: 32513692 PMCID: PMC7322085 DOI: 10.1073/pnas.2001270117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
How G protein-coupled receptors (GPCRs) evoke specific biological outcomes while utilizing a limited array of G proteins and effectors is poorly understood, particularly in native cell systems. Here, we examined signaling evoked by muscarinic (M2R) and adenosine (A1R) receptor activation in the mouse sinoatrial node (SAN), the cardiac pacemaker. M2R and A1R activate a shared pool of cardiac G protein-gated inwardly rectifying K+ (GIRK) channels in SAN cells from adult mice, but A1R-GIRK responses are smaller and slower than M2R-GIRK responses. Recordings from mice lacking Regulator of G protein Signaling 6 (RGS6) revealed that RGS6 exerts a GPCR-dependent influence on GIRK-dependent signaling in SAN cells, suppressing M2R-GIRK coupling efficiency and kinetics and A1R-GIRK signaling amplitude. Fast kinetic bioluminescence resonance energy transfer assays in transfected HEK cells showed that RGS6 prefers Gαo over Gαi as a substrate for its catalytic activity and that M2R signals preferentially via Gαo, while A1R does not discriminate between inhibitory G protein isoforms. The impact of atrial/SAN-selective ablation of Gαo or Gαi2 was consistent with these findings. Gαi2 ablation had minimal impact on M2R-GIRK and A1R-GIRK signaling in SAN cells. In contrast, Gαo ablation decreased the amplitude and slowed the kinetics of M2R-GIRK responses, while enhancing the sensitivity and prolonging the deactivation rate of A1R-GIRK signaling. Collectively, our data show that differences in GPCR-G protein coupling preferences, and the Gαo substrate preference of RGS6, shape A1R- and M2R-GIRK signaling dynamics in mouse SAN cells.
Collapse
Affiliation(s)
- Allison Anderson
- Department of Pharmacology, University of Minnesota, Minneapolis, MN 55455
| | - Ikuo Masuho
- Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458
| | | | - Atsushi Nakano
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, CA 90095
| | - Lutz Birnbaumer
- Neurobiology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709
- Biomedical Research Institute, Catholic University of Argentina, C1107AAZ Buenos Aires, Argentina
| | | | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, MN 55455;
| |
Collapse
|
26
|
Kuß J, Stallmeyer B, Goldstein M, Rinné S, Pees C, Zumhagen S, Seebohm G, Decher N, Pott L, Kienitz MC, Schulze-Bahr E. Familial Sinus Node Disease Caused by a Gain of GIRK (G-Protein Activated Inwardly Rectifying K + Channel) Channel Function. CIRCULATION-GENOMIC AND PRECISION MEDICINE 2020; 12:e002238. [PMID: 30645171 DOI: 10.1161/circgen.118.002238] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Inherited forms of sinus node dysfunction (SND) clinically include bradycardia, sinus arrest, and chronotropic incompetence and may serve as disease models to understand sinus node physiology and impulse generation. Recently, a gain-of-function mutation in the G-protein gene GNB2 led to enhanced activation of the GIRK (G-protein activated inwardly rectifying K+ channel). Thus, human cardiac GIRK channels are important for heart rate regulation and subsequently, genes encoding their subunits Kir3.1 and Kir3.4 ( KCNJ3 and KCNJ5) are potential candidates for inherited SND in human. METHODS We performed a combined approach of targeted sequencing of KCNJ3 and KCNJ5 in 52 patients with idiopathic SND and subsequent whole exome sequencing of additional family members in a genetically affected patient. A putative novel disease-associated gene variant was functionally analyzed by voltage-clamp experiments using various heterologous cell expression systems (Xenopus oocytes, CHO cells, and rat atrial cardiomyocytes). RESULTS In a 3-generation family with SND we identified a novel variant in KCNJ5 which leads to an amino acid substitution (p.Trp101Cys) in the first transmembrane domain of the Kir3.4 subunit of the cardiac GIRK channel. The identified variant cosegregated with the disease in the family and was absent in the Exome Variant Server and Exome Aggregation Consortium databases. Expression of mutant Kir3.4 (±native Kir3.1) in different heterologous cell expression systems resulted in increased GIRK currents ( IK,ACh) and a reduced inward rectification which was not compensated by intracellular spermidine. Moreover, in silico modeling of heterotetrameric mutant GIRK channels indicates a structurally altered binding site for spermine. CONCLUSIONS For the first time, an inherited gain-of-function mutation in the human GIRK3.4 causes familial human SND. The increased activity of GIRK channels is likely to lead to a sustained hyperpolarization of pacemaker cells and thereby reduces heart rate. Modulation of human GIRK channels may pave a way for further treatment of cardiac pacemaking.
Collapse
Affiliation(s)
- Johanna Kuß
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Germany (J.K., B.S., S.Z., G.S., E.S.-B.)
| | - Birgit Stallmeyer
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Germany (J.K., B.S., S.Z., G.S., E.S.-B.)
| | - Matthias Goldstein
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, Germany (M.G., S.R., N.D.)
| | - Susanne Rinné
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, Germany (M.G., S.R., N.D.)
| | - Christiane Pees
- Department of Pediatric Cardiology, University Children's Hospital Vienna, Austria (C.P.)
| | - Sven Zumhagen
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Germany (J.K., B.S., S.Z., G.S., E.S.-B.)
| | - Guiscard Seebohm
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Germany (J.K., B.S., S.Z., G.S., E.S.-B.)
| | - Niels Decher
- Institute of Physiology and Pathophysiology, Vegetative Physiology, University of Marburg, Germany (M.G., S.R., N.D.)
| | - Lutz Pott
- Department of Cardiovascular Medicine, Institute of Physiology, Ruhr-University Bochum, Germany (L.P., M.-C.K.)
| | - Marie-Cécile Kienitz
- Department of Cardiovascular Medicine, Institute of Physiology, Ruhr-University Bochum, Germany (L.P., M.-C.K.)
| | - Eric Schulze-Bahr
- Department of Cardiovascular Medicine, Institute for Genetics of Heart Diseases (IfGH), University Hospital Münster, Germany (J.K., B.S., S.Z., G.S., E.S.-B.)
| |
Collapse
|
27
|
Yamada N, Asano Y, Fujita M, Yamazaki S, Inanobe A, Matsuura N, Kobayashi H, Ohno S, Ebana Y, Tsukamoto O, Ishino S, Takuwa A, Kioka H, Yamashita T, Hashimoto N, Zankov DP, Shimizu A, Asakura M, Asanuma H, Kato H, Nishida Y, Miyashita Y, Shinomiya H, Naiki N, Hayashi K, Makiyama T, Ogita H, Miura K, Ueshima H, Komuro I, Yamagishi M, Horie M, Kawakami K, Furukawa T, Koizumi A, Kurachi Y, Sakata Y, Minamino T, Kitakaze M, Takashima S. Mutant KCNJ3 and KCNJ5 Potassium Channels as Novel Molecular Targets in Bradyarrhythmias and Atrial Fibrillation. Circulation 2020; 139:2157-2169. [PMID: 30764634 DOI: 10.1161/circulationaha.118.036761] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Bradyarrhythmia is a common clinical manifestation. Although the majority of cases are acquired, genetic analysis of families with bradyarrhythmia has identified a growing number of causative gene mutations. Because the only ultimate treatment for symptomatic bradyarrhythmia has been invasive surgical implantation of a pacemaker, the discovery of novel therapeutic molecular targets is necessary to improve prognosis and quality of life. METHODS We investigated a family containing 7 individuals with autosomal dominant bradyarrhythmias of sinus node dysfunction, atrial fibrillation with slow ventricular response, and atrioventricular block. To identify the causative mutation, we conducted the family-based whole exome sequencing and genome-wide linkage analysis. We characterized the mutation-related mechanisms based on the pathophysiology in vitro. After generating a transgenic animal model to confirm the human phenotypes of bradyarrhythmia, we also evaluated the efficacy of a newly identified molecular-targeted compound to upregulate heart rate in bradyarrhythmias by using the animal model. RESULTS We identified one heterozygous mutation, KCNJ3 c.247A>C, p.N83H, as a novel cause of hereditary bradyarrhythmias in this family. KCNJ3 encodes the inwardly rectifying potassium channel Kir3.1, which combines with Kir3.4 (encoded by KCNJ5) to form the acetylcholine-activated potassium channel ( IKACh channel) with specific expression in the atrium. An additional study using a genome cohort of 2185 patients with sporadic atrial fibrillation revealed another 5 rare mutations in KCNJ3 and KCNJ5, suggesting the relevance of both genes to these arrhythmias. Cellular electrophysiological studies revealed that the KCNJ3 p.N83H mutation caused a gain of IKACh channel function by increasing the basal current, even in the absence of m2 muscarinic receptor stimulation. We generated transgenic zebrafish expressing mutant human KCNJ3 in the atrium specifically. It is interesting to note that the selective IKACh channel blocker NIP-151 repressed the increased current and improved bradyarrhythmia phenotypes in the mutant zebrafish. CONCLUSIONS The IKACh channel is associated with the pathophysiology of bradyarrhythmia and atrial fibrillation, and the mutant IKACh channel ( KCNJ3 p.N83H) can be effectively inhibited by NIP-151, a selective IKACh channel blocker. Thus, the IKACh channel might be considered to be a suitable pharmacological target for patients who have bradyarrhythmia with a gain-of-function mutation in the IKACh channel.
Collapse
Affiliation(s)
- Noriaki Yamada
- Departments of Cardiovascular Medicine (N.Y., Y.A., A.T., H. Kioka, Y.M., H.S., Y.S.), Osaka University Graduate School of Medicine, Suita, Japan
| | - Yoshihiro Asano
- Departments of Cardiovascular Medicine (N.Y., Y.A., A.T., H. Kioka, Y.M., H.S., Y.S.), Osaka University Graduate School of Medicine, Suita, Japan
| | - Masashi Fujita
- Department of Onco-cardiology, Osaka International Cancer Institute, Japan (M.F.)
| | - Satoru Yamazaki
- Departments of Cell Biology (S.Y.), National Cerebral and Cardiovascular Center, Suita, Japan
| | - Atsushi Inanobe
- Pharmacology (A.I., Y.K.), Osaka University Graduate School of Medicine, Suita, Japan
| | - Norio Matsuura
- Departments of Health and Environmental Sciences (N.M.), Kyoto University Graduate School of Medicine, Japan
| | - Hatasu Kobayashi
- Department of Biomedical Sciences, College of Life and Health Sciences Chubu University, Kasugai, Japan (H. Kobayashi)
| | - Seiko Ohno
- Bioscience and Genetics (S.O.), National Cerebral and Cardiovascular Center, Suita, Japan.,Center for Epidemiologic Research in Asia (S.O., K.M., H.U., M.H.), Shiga University of Medical Science, Otsu, Japan
| | - Yusuke Ebana
- Life Science and Bioethics Research Center (Y.E.), Tokyo Medical and Dental University, Japan
| | - Osamu Tsukamoto
- Medical Biochemistry (O.T., H. Kato, Y.N., S.T.), Osaka University Graduate School of Medicine, Suita, Japan
| | - Saki Ishino
- Center of Medical Innovation and Translational Research (S.I.), Osaka University Graduate School of Medicine, Suita, Japan
| | - Ayako Takuwa
- Departments of Cardiovascular Medicine (N.Y., Y.A., A.T., H. Kioka, Y.M., H.S., Y.S.), Osaka University Graduate School of Medicine, Suita, Japan
| | - Hidetaka Kioka
- Departments of Cardiovascular Medicine (N.Y., Y.A., A.T., H. Kioka, Y.M., H.S., Y.S.), Osaka University Graduate School of Medicine, Suita, Japan
| | - Toru Yamashita
- Pharmaceuticals Division, Nissan Chemical Corporation, Tokyo, Japan (T.Y., N.H.)
| | - Norio Hashimoto
- Pharmaceuticals Division, Nissan Chemical Corporation, Tokyo, Japan (T.Y., N.H.)
| | - Dimitar P Zankov
- Division of Molecular Medical Biochemistry, Department of Biochemistry and Molecular Biology (D.P.Z., A.S., H.O.), Shiga University of Medical Science, Otsu, Japan
| | - Akio Shimizu
- Division of Molecular Medical Biochemistry, Department of Biochemistry and Molecular Biology (D.P.Z., A.S., H.O.), Shiga University of Medical Science, Otsu, Japan
| | - Masanori Asakura
- Cardiovascular Division, Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan (M.A.)
| | - Hiroshi Asanuma
- Department of Internal Medicine, Meiji University of Integrative Medicine, Nantan, Japan (H.A.)
| | - Hisakazu Kato
- Medical Biochemistry (O.T., H. Kato, Y.N., S.T.), Osaka University Graduate School of Medicine, Suita, Japan
| | - Yuya Nishida
- Medical Biochemistry (O.T., H. Kato, Y.N., S.T.), Osaka University Graduate School of Medicine, Suita, Japan
| | - Yohei Miyashita
- Departments of Cardiovascular Medicine (N.Y., Y.A., A.T., H. Kioka, Y.M., H.S., Y.S.), Osaka University Graduate School of Medicine, Suita, Japan
| | - Haruki Shinomiya
- Departments of Cardiovascular Medicine (N.Y., Y.A., A.T., H. Kioka, Y.M., H.S., Y.S.), Osaka University Graduate School of Medicine, Suita, Japan
| | - Nobu Naiki
- Departments of Cardiovascular Medicine (N.N., M.H.), Shiga University of Medical Science, Otsu, Japan
| | - Kenshi Hayashi
- Department of Cardiovascular and Internal Medicine, Kanazawa University Graduate School of Medicine, Kanazawa, Japan (K.H., M.Y.)
| | - Takeru Makiyama
- Cardiovascular Medicine (T. Makiyama), Kyoto University Graduate School of Medicine, Japan
| | - Hisakazu Ogita
- Division of Molecular Medical Biochemistry, Department of Biochemistry and Molecular Biology (D.P.Z., A.S., H.O.), Shiga University of Medical Science, Otsu, Japan
| | - Katsuyuki Miura
- Center for Epidemiologic Research in Asia (S.O., K.M., H.U., M.H.), Shiga University of Medical Science, Otsu, Japan.,Public Health (K.M., H.U.), Shiga University of Medical Science, Otsu, Japan
| | - Hirotsugu Ueshima
- Center for Epidemiologic Research in Asia (S.O., K.M., H.U., M.H.), Shiga University of Medical Science, Otsu, Japan.,Public Health (K.M., H.U.), Shiga University of Medical Science, Otsu, Japan
| | - Issei Komuro
- Department of Cardiovascular Medicine, The University of Tokyo Graduate School of Medicine, Japan (I.K.)
| | - Masakazu Yamagishi
- Department of Cardiovascular and Internal Medicine, Kanazawa University Graduate School of Medicine, Kanazawa, Japan (K.H., M.Y.).,Department of Human Sciences, Osaka University of Human Sciences, Settsu, Japan (M.Y.)
| | - Minoru Horie
- Center for Epidemiologic Research in Asia (S.O., K.M., H.U., M.H.), Shiga University of Medical Science, Otsu, Japan.,Departments of Cardiovascular Medicine (N.N., M.H.), Shiga University of Medical Science, Otsu, Japan
| | - Koichi Kawakami
- Division of Molecular and Developmental Biology, National Institute of Genetics, Mishima, Japan (K.K.).,Department of Genetics, SOKENDAI (The Graduate University for Advanced Studies), Mishima, Japan (K.K.)
| | - Tetsushi Furukawa
- Department of Bioinformational Pharmacology (T.F.), Tokyo Medical and Dental University, Japan
| | - Akio Koizumi
- Public Interest Foundation Kyoto Hokenkai, Japan (A.K.)
| | - Yoshihisa Kurachi
- Pharmacology (A.I., Y.K.), Osaka University Graduate School of Medicine, Suita, Japan
| | - Yasushi Sakata
- Departments of Cardiovascular Medicine (N.Y., Y.A., A.T., H. Kioka, Y.M., H.S., Y.S.), Osaka University Graduate School of Medicine, Suita, Japan
| | - Tetsuo Minamino
- Department of Cardiorenal and Cerebrovascular Medicine, Faculty of Medicine, Kagawa University, Japan (T. Minamino)
| | - Masafumi Kitakaze
- Clinical Medicine and Development (M.K.), National Cerebral and Cardiovascular Center, Suita, Japan
| | - Seiji Takashima
- Medical Biochemistry (O.T., H. Kato, Y.N., S.T.), Osaka University Graduate School of Medicine, Suita, Japan
| |
Collapse
|
28
|
Zhou Q, Chen B, Chen X, Wang Y, Ji J, Kizaibek M, Wang X, Wu L, Hu Z, Gao X, Wu N, Huang D, Xu X, Lu W, Cai X, Yang Y, Ye J, Wei Q, Shen J, Cao P. Arnebiae Radix prevents atrial fibrillation in rats by ameliorating atrial remodeling and cardiac function. JOURNAL OF ETHNOPHARMACOLOGY 2020; 248:112317. [PMID: 31629862 DOI: 10.1016/j.jep.2019.112317] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 07/27/2019] [Accepted: 10/16/2019] [Indexed: 06/10/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Arnebiae Radix, a common herbal medicine in China, is often utilized to treat blood-heat syndrome and has been reported to exert an effect on the heart. AIM OF THE STUDY The combination of acetylcholine (Ach) and CaCl2 has been widely used to induce atrial fibrillation (AF) in animals. However, whether Arnebiae Radix displays any preventive action on Ach-CaCl2 induced AF in rats remains uncertain. In our study, we attempted to investigate the protective effects of Arnebiae Radix on Ach-CaCl2 induced AF compared to amiodarone, which was employed as the positive control. MATERIALS AND METHODS To establish the AF model, SD rats were treated with a mixture of 0.1 mL/100 g Ach-CaCl2 (60 μg/mL Ach and 10 mg/mL CaCl2) by tail vein injection for 7 days. Rats were also given a gavage of Arnebiae Radix (0.18 g/mL) one week before or concurrently with the establishment of the AF model. At the end of the experimental period, the induction, duration and timing of AF were monitored using electrocardiogram recordings. Left atrial tissues were stained to observe the level of fibrosis. Electrophysiological measurements were used to examine atrial size and function. RESULTS In Ach-CaCl2-induced AF rats, Arnebiae Radix decreased AF induction, duration and susceptibility to AF. In addition, Arnebiae Radix significantly reduced atrial fibrosis and inhibited atrial enlargement induced by Ach-CaCl2. Moreover, there was an apparent improvement in cardiac function in the Arnebiae Radix-treated group. CONCLUSIONS Our findings indicate that Arnebiae Radix treatment can attenuate Ach-CaCl2-induced atrial injury and serve as an effective therapeutic strategy for the treatment of AF in the future.
Collapse
Affiliation(s)
- Qian Zhou
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Bin Chen
- Nanjing Research Institute for Comprehensive Utilization of Wild Plants, Nanjing, 210042, Jiangsu, China
| | - Xiaodong Chen
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Yue Wang
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Jiawen Ji
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Murat Kizaibek
- Traditional Kazakh Medicine Research Institute of Ili Kazakh Autonomous Prefecture, Traditional Chinese Medicine Hospital of Ili Kazakh Autonomous Prefecture, Yining, Xinjiang, 835000, China
| | - Xindong Wang
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Lixing Wu
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Zhengli Hu
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Xin Gao
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Na Wu
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Dan Huang
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Xiaojin Xu
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Wuguang Lu
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Xueting Cai
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Yang Yang
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Juan Ye
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Qingyun Wei
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China
| | - Jianping Shen
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China.
| | - Peng Cao
- Affiliated Hospital of Integrated Traditional Chinese and Western Medicine, Nanjing University of Chinese Medicine, Nanjing, 210028, Jiangsu, China; College of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 210023, Jiangsu, China.
| |
Collapse
|
29
|
Chadda KR, Fazmin IT, Ahmad S, Valli H, Edling CE, Huang CLH, Jeevaratnam K. Arrhythmogenic mechanisms of obstructive sleep apnea in heart failure patients. Sleep 2019; 41:5054592. [PMID: 30016501 DOI: 10.1093/sleep/zsy136] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 07/13/2018] [Indexed: 01/01/2023] Open
Abstract
Heart failure (HF) affects 23 million people worldwide and results in 300000 annual deaths. It is associated with many comorbidities, such as obstructive sleep apnea (OSA), and risk factors for both conditions overlap. Eleven percent of HF patients have OSA and 7.7% of OSA patients have left ventricular ejection fraction <50% with arrhythmias being a significant comorbidity in HF and OSA patients. Forty percent of HF patients develop atrial fibrillation (AF) and 30%-50% of deaths from cardiac causes in HF patients are from sudden cardiac death. OSA is prevalent in 32%-49% of patients with AF and there is a dose-dependent relationship between OSA severity and resistance to anti-arrhythmic therapies. HF and OSA lead to various downstream arrhythmogenic mechanisms, including metabolic derangement, remodeling, inflammation, and autonomic imbalance. (1) Metabolic derangement and production of reactive oxidative species increase late Na+ currents, decrease outward K+ currents and downregulate connexin-43 and cell-cell coupling. (2) remodeling also features downregulated K+ currents in addition to decreased Na+/K+ ATPase currents, altered Ca2+ homeostasis, and increased density of If current. (3) Chronic inflammation leads to downregulation of both Nav1.5 channels and K+ channels, altered Ca2+ homeostasis and reduced cellular coupling from alterations of connexin expression. (4) Autonomic imbalance causes arrhythmias by evoking triggered activity through increased Ca2+ transients and reduction of excitation wavefront wavelength. Thus, consideration of these multiple pathophysiological pathways (1-4) will enable the development of novel therapeutic strategies that can be targeted against arrhythmias in the context of complex disease, such as the comorbidities of HF and OSA.
Collapse
Affiliation(s)
- Karan R Chadda
- Faculty of Health and Medical Science, University of Surrey, Guildford, United Kingdom.,Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, United Kingdom
| | - Ibrahim T Fazmin
- Faculty of Health and Medical Science, University of Surrey, Guildford, United Kingdom.,Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, United Kingdom
| | - Shiraz Ahmad
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, United Kingdom
| | - Haseeb Valli
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, United Kingdom
| | - Charlotte E Edling
- Faculty of Health and Medical Science, University of Surrey, Guildford, United Kingdom
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, United Kingdom.,Department of Biochemistry, Hopkins Building, University of Cambridge, Cambridge, United Kingdom
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Science, University of Surrey, Guildford, United Kingdom.,Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, United Kingdom
| |
Collapse
|
30
|
Association of Autoantibodies against M2-Muscarinic Acetylcholine Receptor with Atrial Fibrosis in Atrial Fibrillation Patients. Cardiol Res Pract 2019; 2019:8271871. [PMID: 30863630 PMCID: PMC6378765 DOI: 10.1155/2019/8271871] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 01/01/2019] [Indexed: 01/22/2023] Open
Abstract
Objectives To investigate the association of serum autoantibodies against M2-muscarinic acetylcholine receptor (anti-M2-R) with atrial fibrosis in long-standing persistent atrial fibrillation (AF) patients. Methods Twenty-four long-standing persistent AF patients, scheduled to undergo hybrid ablation surgery, were enrolled in the study. Twenty-six patients with sinus rhythm, scheduled to undergo coronary artery bypass grafting surgery, were enrolled into the non-AF group. We detected serum anti-M2-R levels. Left atrial appendages were subjected to histological and molecular biological assays. Patients in the AF group received follow-up for two years. Results The AF group showed significantly higher serum anti-M2-R levels compared to the non-AF group (496.2 ± 232.5 vs. 86.3 ± 25.7 pmol/L, p < 0.001). The AF group exhibited severe fibrosis in the left atrial appendages, as indicated by increased collagen volume fraction (45.2 ± 4.7% vs. 27.6 ± 8.3%, p < 0.001), and higher levels of collagen I (0.52 ± 0.04 vs. 0.24 ± 0.06, p < 0.001) and collagen III (0.51 ± 0.07 vs. 0.36 ± 0.09, p < 0.001). TGF-β1 and CTGF were also upregulated in the AF group. A positive correlation between serum anti-M2-R levels and fibrosis of the left atrial appendage and fibrogenic indexes was observed. Conclusions Serum anti-M2-R levels are higher in AF patients and are associated with the severity of atrial fibrosis. In addition, serum anti-M2-R levels are positively correlated to TGF-β1 and CTGF expression in the left atrial appendage.
Collapse
|
31
|
Yuan D, Zheng P, Tan C, Huang SH, Li D, Huang J. Influence of Continuous Training on Atrial Myocytes I K1 and I KAch and on Induction of Atrial Fibrillation in a Rabbit Model. Cardiol Res Pract 2018; 2018:3795608. [PMID: 30662768 PMCID: PMC6313976 DOI: 10.1155/2018/3795608] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 11/01/2018] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Elucidation of mechanisms underlying continuous training-related atrial fibrillation (AF) may inform formulation of novel therapeutic approaches and training method selection. This study was aimed at assessing mechanisms underlying continuous training-induced AF in an animal model. METHODS Healthy New Zealand rabbits were divided into three groups (n=8 each), namely, control (C), and moderate intensity (M), and high intensity (H) continuous training according to treadmill speed. Atrial size andintrinsic and resting heart rates were measured by transthoracic echocardiography before, and 8 and 12 weeks after training. Using a Langendorff perfusion system, AF was induced by S1S2 stimulation and the induction rate was recorded. Atrial IK1 and IKAch ion current densities were recorded using whole-cell patch-clamp technique in isolated atrial myocytes. Changes in atrial Kir2.1, Kir2.2, Kir3.1, and Kir3.4 mRNA expression were assessed by reverse transcriptase-coupled polymerase chain reaction. RESULTS After 8 and 12 weeks, Groups M and H vs. Group C had greater (all P < 0.05) atrial anteroposterior diameter; greater incidence of AF (60% and 90% vs. 45%, respectively; P < 0.05, also between Groups H and M); and greater atrial IKAch current density. In Group H, Kir2.1 and Kir2.2 mRNA expression in the left and right atria was increased (P < 0.05, vs. Groups C and M) as was left atrial Kir3.1 and Kir3.4 mRNA expression (P < 0.05, vs. Group C). CONCLUSION In a rabbit model, continuous training enlarges atrial diameter leading to atrial structural and electrical remodeling and increased AF incidence.
Collapse
Affiliation(s)
- Dou Yuan
- Department of Thoracic and Cardiovascular Surgery, Cheng Du Shang Jin Nan Fu Hospital, West China Hospital of Sichuan University, Chengdu, China
| | - Ping Zheng
- Clinical Department of Strategic Support Force Aerospace Systems in Beijing Space City, Beijing, China
| | - Chen Tan
- Department of Cardiology, HeBei Yan Da Hospital, Langfang, China
| | - Si Hui Huang
- Department of Cardiology, Peking University First Hospital, Beijing, China
| | - Dan Li
- Department of Ultrasound, PLA Army General Hopsital, Beijing, China
| | - Jian Huang
- Fuwai Heart Disease Hospital, CAMS and PUMC, Beijing, China
| |
Collapse
|
32
|
Yang Q, Lv Q, Feng M, Liu M, Feng Y, Lin S, Yang J, Hu J. Taurine Prevents the Electrical Remodeling in Ach-CaCl 2 Induced Atrial Fibrillation in Rats. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 975 Pt 2:821-830. [PMID: 28849502 DOI: 10.1007/978-94-024-1079-2_64] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
OBJECTIVE To study the preventive actions and mechanism of taurine on the electrical remodeling in atrial fibrillation (AF) rats. METHODS Male Wistar rats were injected with the mixture of acetylcholine (Ach) (66 μg/mL)-CaCl2 (10 mg/mL) (i.v.) for 7 days to establish AF model. Taurine was administered in drinking water 1 week before or at the same time of AF model establishment. The duration of AF was monitored by recording ECG of rats during the model establishment. At the end of the experiment, left atrial appendages were cut down to measure the effective refractory period (ERP) by S1-S2 double stimulation method; atrial tissues were collected in order to detect the concentration of K+ and taurine by flame atomic absorption spectrometry and ELISA respectively; total RNA were extracted from the atrium, gene expressions of Kv1.5, Kv4.3, Kir2.1, Kir3.4 were detected by semi-quantitative RT-PCR. RESULTS Taurine administration effectively shortened the AF duration of rats and prolonged atrial ERP than the model and taurine depleted rats. In addition, atrial K+ level in taurine treated groups was significantly reduced nearly to the normal level. Moreover, the mRNA expression levels of Kir3.4 and Kv1.5 were significantly increased in the taurine preventive treated groups. CONCLUSIONS Taurine can prevent the atrial electrical remodeling and decrease the duration of AF in rats by reducing the atrial K+ concentration and up-regulating mRNA expression levels of Kir3.4 and Kv1.5.
Collapse
Affiliation(s)
- Qunhui Yang
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China
| | - Qiufeng Lv
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China
| | - Man Feng
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China
| | - Mei Liu
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China
| | - Ying Feng
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China
| | - Shumei Lin
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China
| | - Jiancheng Yang
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China
| | - Jianmin Hu
- Liaoning Provincial Key Laboratory of Zoonosis, College of Animal Science and Veterinary Medicine, Shenyang Agricultural University, Shenyang, Liaoning, 110866, People's Republic of China.
| |
Collapse
|
33
|
Salazar-Fajardo PD, Aréchiga-Figueroa IA, López-Serrano AL, Rodriguez-Elias JC, Alamilla J, Sánchez-Chapula JA, Tristani-Firouzi M, Navarro-Polanco RA, Moreno-Galindo EG. The voltage-sensitive cardiac M 2 muscarinic receptor modulates the inward rectification of the G protein-coupled, ACh-gated K + current. Pflugers Arch 2018; 470:1765-1776. [PMID: 30155776 DOI: 10.1007/s00424-018-2196-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 07/28/2018] [Accepted: 08/13/2018] [Indexed: 11/25/2022]
Abstract
The acetylcholine (ACh)-gated inwardly rectifying K+ current (IKACh) plays a vital role in cardiac excitability by regulating heart rate variability and vulnerability to atrial arrhythmias. These crucial physiological contributions are determined principally by the inwardly rectifying nature of IKACh. Here, we investigated the relative contribution of two distinct mechanisms of IKACh inward rectification measured in atrial myocytes: a rapid component due to KACh channel block by intracellular Mg2+ and polyamines; and a time- and concentration-dependent mechanism. The time- and ACh concentration-dependent inward rectification component was eliminated when IKACh was activated by GTPγS, a compound that bypasses the muscarinic-2 receptor (M2R) and directly stimulates trimeric G proteins to open KACh channels. Moreover, the time-dependent component of IKACh inward rectification was also eliminated at ACh concentrations that saturate the receptor. These observations indicate that the time- and concentration-dependent rectification mechanism is an intrinsic property of the receptor, M2R; consistent with our previous work demonstrating that voltage-dependent conformational changes in the M2R alter the receptor affinity for ACh. Our analysis of the initial and time-dependent components of IKACh indicate that rapid Mg2+-polyamine block accounts for 60-70% of inward rectification, with M2R voltage sensitivity contributing 30-40% at sub-saturating ACh concentrations. Thus, while both inward rectification mechanisms are extrinsic to the KACh channel, to our knowledge, this is the first description of extrinsic inward rectification of ionic current attributable to an intrinsic voltage-sensitive property of a G protein-coupled receptor.
Collapse
Affiliation(s)
- Pedro D Salazar-Fajardo
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, C.P, 28045, Colima, COL, Mexico
| | - Iván A Aréchiga-Figueroa
- CONACyT, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, SLP, Mexico
| | - Ana Laura López-Serrano
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, C.P, 28045, Colima, COL, Mexico
| | - Julio C Rodriguez-Elias
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, C.P, 28045, Colima, COL, Mexico
| | - Javier Alamilla
- CONACyT, Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, COL, Mexico
| | - José A Sánchez-Chapula
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, C.P, 28045, Colima, COL, Mexico
| | - Martin Tristani-Firouzi
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, 84112, USA.
| | - Ricardo A Navarro-Polanco
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, C.P, 28045, Colima, COL, Mexico.
| | - Eloy G Moreno-Galindo
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Av. 25 de Julio 965, Colonia Villa San Sebastián, C.P, 28045, Colima, COL, Mexico.
| |
Collapse
|
34
|
Lee SW, Anderson A, Guzman PA, Nakano A, Tolkacheva EG, Wickman K. Atrial GIRK Channels Mediate the Effects of Vagus Nerve Stimulation on Heart Rate Dynamics and Arrhythmogenesis. Front Physiol 2018; 9:943. [PMID: 30072916 PMCID: PMC6060443 DOI: 10.3389/fphys.2018.00943] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 06/27/2018] [Indexed: 01/09/2023] Open
Abstract
Diminished parasympathetic influence is central to the pathogenesis of cardiovascular diseases, including heart failure and hypertension. Stimulation of the vagus nerve has shown promise in treating cardiovascular disease, prompting renewed interest in understanding the signaling pathway(s) that mediate the vagal influence on cardiac physiology. Here, we evaluated the contribution of G protein-gated inwardly rectifying K+ (GIRK/Kir3) channels to the effect of vagus nerve stimulation (VNS) on heart rate (HR), HR variability (HRV), and arrhythmogenesis in anesthetized mice. As parasympathetic fibers innervate both atria and ventricle, and GIRK channels contribute to the cholinergic impact on atrial and ventricular myocytes, we collected in vivo electrocardiogram recordings from mice lacking either atrial or ventricular GIRK channels, during VNS. VNS decreased HR and increased HRV in control mice, in a muscarinic receptor-dependent manner. This effect was preserved in mice lacking ventricular GIRK channels, but was nearly completely absent in mice lacking GIRK channels in the atria. In addition, atrial-specific ablation of GIRK channels conferred resistance to arrhythmic episodes induced by VNS. These data indicate that atrial GIRK channels are the primary mediators of the impact of VNS on HR, HRV, and arrhythmogenesis in the anesthetized mouse.
Collapse
Affiliation(s)
- Steven W. Lee
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Allison Anderson
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
| | - Pilar A. Guzman
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, United States
| | - Atsushi Nakano
- Department of Molecular, Cell, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA, United States
| | - Elena G. Tolkacheva
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
| |
Collapse
|
35
|
Abstract
Atrial fibrillation (AF) is the most common sustained arrhythmia and is associated with pronounced morbidity and mortality. Its prevalence, expected to further increase for the forthcoming years, and associated frequent hospitalizations turn AF into a major health problem. Structural and electrical atrial remodelling underlie the substrate for AF, but the exact mechanisms driving this remodelling remain incompletely understood. Recent studies have shown that microRNAs (miRNA), short non-coding RNAs that regulate gene expression, may be involved in the pathophysiology of AF. MiRNAs have been implicated in AF-induced ion channel remodelling and fibrosis. MiRNAs could therefore provide insight into AF pathophysiology or become novel targets for therapy with miRNA mimics or anti-miRNAs. Moreover, circulating miRNAs have been suggested as a new class of diagnostic and prognostic biomarkers of AF. However, the origin and function of miRNAs in tissue and plasma frequently remain unknown and studies investigating the role of miRNAs in AF vary in design and focus and even present contradicting results. Here, we provide a systematic review of the available clinical and functional studies investigating the tissue and plasma miRNAs in AF and will thereafter discuss the potential of miRNAs as biomarkers or novel therapeutic targets in AF.
Collapse
|
36
|
Calvo D, Filgueiras-Rama D, Jalife J. Mechanisms and Drug Development in Atrial Fibrillation. Pharmacol Rev 2018; 70:505-525. [PMID: 29921647 PMCID: PMC6010660 DOI: 10.1124/pr.117.014183] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation is a highly prevalent cardiac arrhythmia and the most important cause of embolic stroke. Although genetic studies have identified an increasing assembly of AF-related genes, the impact of these genetic discoveries is yet to be realized. In addition, despite more than a century of research and speculation, the molecular and cellular mechanisms underlying AF have not been established, and therapy for AF, particularly persistent AF, remains suboptimal. Current antiarrhythmic drugs are associated with a significant rate of adverse events, particularly proarrhythmia, which may explain why many highly symptomatic AF patients are not receiving any rhythm control therapy. This review focuses on recent advances in AF research, including its epidemiology, genetics, and pathophysiological mechanisms. We then discuss the status of antiarrhythmic drug therapy for AF today, reviewing molecular mechanisms, and the possible clinical use of some of the new atrial-selective antifibrillatory agents, as well as drugs that target atrial remodeling, inflammation and fibrosis, which are being tested as upstream therapies to prevent AF perpetuation. Altogether, the objective is to highlight the magnitude and endemic dimension of AF, which requires a significant effort to develop new and effective antiarrhythmic drugs, but also improve AF prevention and treatment of risk factors that are associated with AF complications.
Collapse
Affiliation(s)
- David Calvo
- Department of Cardiology, Arrhythmia Unit, Hospital Universitario Central de Asturias and Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain (D.C.); Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain (D.F.-R., J.J.); Department of Cardiology, Arrhythmia Unit, Hospital Clínico Universitario San Carlos, Madrid, Spain (D.F.-R.); Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain (D.F.-R., J.J.); and Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan (J.J.)
| | - David Filgueiras-Rama
- Department of Cardiology, Arrhythmia Unit, Hospital Universitario Central de Asturias and Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain (D.C.); Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain (D.F.-R., J.J.); Department of Cardiology, Arrhythmia Unit, Hospital Clínico Universitario San Carlos, Madrid, Spain (D.F.-R.); Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain (D.F.-R., J.J.); and Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan (J.J.)
| | - José Jalife
- Department of Cardiology, Arrhythmia Unit, Hospital Universitario Central de Asturias and Instituto de Investigación Sanitaria del Principado de Asturias, Oviedo, Spain (D.C.); Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain (D.F.-R., J.J.); Department of Cardiology, Arrhythmia Unit, Hospital Clínico Universitario San Carlos, Madrid, Spain (D.F.-R.); Centro de Investigación Biomédica en Red de Enfermedades Cardiovasculares (CIBERCV), Madrid, Spain (D.F.-R., J.J.); and Center for Arrhythmia Research, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan (J.J.)
| |
Collapse
|
37
|
Skarsfeldt MA, Bomholtz SH, Lundegaard PR, Lopez-Izquierdo A, Tristani-Firouzi M, Bentzen BH. Atrium-specific ion channels in the zebrafish-A role of I KACh in atrial repolarization. Acta Physiol (Oxf) 2018; 223:e13049. [PMID: 29412518 DOI: 10.1111/apha.13049] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 01/26/2018] [Accepted: 01/29/2018] [Indexed: 12/16/2022]
Abstract
AIM The zebrafish has emerged as a novel model for investigating cardiac physiology and pathology. The aim of this study was to investigate the atrium-specific ion channels responsible for shaping the atrial cardiac action potential in zebrafish. METHODS Using quantitative polymerase chain reaction, we assessed the expression level of atrium-specific potassium channels. The functional role of these channels was studied by patch clamp experiments on isolated atrial and ventricular cardiomyocytes and by optical mapping of explanted adult zebrafish hearts. Finally, surface ECGs were recorded to establish possible in vivo roles of atrial ion channels. RESULTS In isolated adult zebrafish hearts, we identified the expression of kcnk3, kcnk9, kcnn1, kcnn2, kcnn3, kcnj3 and kcnj5, the genes that encode the atrium-specific K2P , KCa 2.x and Kir 3.1/4 (KACh ) ion channels. The electrophysiological data indicate that the acetylcholine-activated inward-rectifying current, IKACh, plays a major role in the zebrafish atrium, whereas K2P 3.1/9.1 and KCa 2.x channels do not appear to be involved in regulating the action potential in the zebrafish heart. CONCLUSION We demonstrate that the acetylcholine-activated inward-rectifying current (IKACh ) current plays a major role in the zebrafish atrium and that the zebrafish could potentially be a cost-effective and reliable model for pharmacological testing of atrium-specific IKACh modulating compounds.
Collapse
Affiliation(s)
- M. A. Skarsfeldt
- Department of Biomedical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen N Denmark
- Nora Eccles Harrison Cardiovascular Research and Training Institute; University of Utah; Salt Lake City UT USA
| | - S. H. Bomholtz
- Department of Biomedical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen N Denmark
| | - P. R. Lundegaard
- Department of Biomedical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen N Denmark
| | - A. Lopez-Izquierdo
- Nora Eccles Harrison Cardiovascular Research and Training Institute; University of Utah; Salt Lake City UT USA
| | - M. Tristani-Firouzi
- Nora Eccles Harrison Cardiovascular Research and Training Institute; University of Utah; Salt Lake City UT USA
| | - B. H. Bentzen
- Department of Biomedical Sciences; Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen N Denmark
| |
Collapse
|
38
|
Kulkarni K, Xie X, Fernandez de Velasco EM, Anderson A, Martemyanov KA, Wickman K, Tolkacheva EG. The influences of the M2R-GIRK4-RGS6 dependent parasympathetic pathway on electrophysiological properties of the mouse heart. PLoS One 2018; 13:e0193798. [PMID: 29668674 PMCID: PMC5905881 DOI: 10.1371/journal.pone.0193798] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 02/20/2018] [Indexed: 02/07/2023] Open
Abstract
A large body of work has established the prominent roles of the atrial M2R-IKACh signaling pathway, and the negative regulatory protein RGS6, in modulating critical aspects of parasympathetic influence on cardiac function, including pace-making, heart rate (HR) variability (HRV), and atrial arrhythmogenesis. Despite increasing evidence of its innervation of the ventricles, and the expression of M2R, IKACh channel subunits, and RGS6 in ventricle, the effects of parasympathetic modulation on ventricular electrophysiology are less clear. The main objective of our study was to investigate the contribution of M2R-IKACh signaling pathway elements in murine ventricular electrophysiology, using in-vivo ECG measurements, isolated whole-heart optical mapping and constitutive knockout mice lacking IKACh (Girk4–/–) or RGS6 (Rgs6-/-). Consistent with previous findings, mice lacking GIRK4 exhibited diminished HR and HRV responses to the cholinergic agonist carbachol (CCh), and resistance to CCh-induced arrhythmic episodes. In line with its role as a negative regulator of atrial M2R-IKACh signaling, loss of RGS6 correlated with a mild resting bradycardia, enhanced HR and HRV responses to CCh, and increased propensity for arrhythmic episodes. Interestingly, ventricles from mice lacking GIRK4 or RGS6 both exhibited increased action potential duration (APD) at baseline, and APD was prolonged by CCh across all genotypes. Similarly, CCh significantly increased the slope of APD restitution in all genotypes. There was no impact of genotype or CCh on either conduction velocity or heterogeneity. Our data suggests that altered parasympathetic signaling through the M2R-IKACh pathway can affect ventricular electrophysiological properties distinct from its influence on atrial physiology.
Collapse
Affiliation(s)
- Kanchan Kulkarni
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Xueyi Xie
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, United States of America
| | | | - Allison Anderson
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Kirill A. Martemyanov
- Department of Neuroscience, The Scripps Research Institute, Jupiter, Florida, United States of America
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Elena G. Tolkacheva
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota, United States of America
- * E-mail:
| |
Collapse
|
39
|
Abstract
BACKGROUND Atrial fibrillation (AF) is initiated through arrhythmic atrial excitation from outside the sinus node or remodeling of atrial tissue that allows reentry of excitation. Angiotensin II (AngII) has been implicated in the initiation and maintenance of AF through changes in Ca2+ handling and production of reactive oxygen species (ROS). OBJECTIVE We aimed to determine the role of p21-activated kinase 1 (Pak1), a downstream target in the AngII signaling cascade, in atrial electrophysiology and arrhythmia. METHODS Wild-type and Pak1-/- mice were used to determine atrial function in vivo on the organ and cellular level by quantification of electrophysiological and Ca2+ handling properties. RESULTS We demonstrate that reduced Pak1 activity increases the inducibility of atrial arrhythmia in vivo and in vitro. On the cellular level, Pak1-/- atrial myocytes (AMs) exhibit increased basal and AngII (1 μM)-induced ROS production, sensitivity to the NADPH oxidase-2 (NOX2) inhibitors gp91ds-tat and apocynin (1 μM), and enhanced membrane translocation of Ras-related C3 substrate 1 (Rac1) that is part of the multimolecular NOX2 complex. Upon stimulation with AngII, Pak1-/- AMs exhibit an exaggerated increase in the intracellular Calcium concentration ([Ca2+]i) and arrhythmic events that were sensitive to sodium-calcium exchanger (NCX) inhibitors (KB-R7943 and SEA0400; 1 μM) and suppressed in AMs from NOX2-deficient (gp91phox-/-) mice. Pak1 stimulation (FTY720; 200 nM) in wild-type AMs and AMs from a canine model of ventricular tachypacing-induced AF prevented AngII-induced arrhythmic Ca2+ overload by attenuating NCX activity in a NOX2-dependent manner. CONCLUSION The experimental results support that Pak1 stimulation can attenuate NCX-dependent Ca2+ overload and prevent triggered arrhythmic activity by suppressing NOX2-dependent ROS production.
Collapse
|
40
|
Expression and relevance of the G protein-gated K + channel in the mouse ventricle. Sci Rep 2018; 8:1192. [PMID: 29352184 PMCID: PMC5775354 DOI: 10.1038/s41598-018-19719-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 01/08/2018] [Indexed: 12/31/2022] Open
Abstract
The atrial G protein-gated inwardly rectifying K+ (GIRK) channel is a critical mediator of parasympathetic influence on cardiac physiology. Here, we probed the details and relevance of the GIRK channel in mouse ventricle. mRNAs for the atrial GIRK channel subunits (GIRK1, GIRK4), M2 muscarinic receptor (M2R), and RGS6, a negative regulator of atrial GIRK-dependent signaling, were detected in mouse ventricle at relatively low levels. The cholinergic agonist carbachol (CCh) activated small GIRK currents in adult wild-type ventricular myocytes that exhibited relatively slow kinetics and low CCh sensitivity; these currents were absent in ventricular myocytes from Girk1-/- or Girk4-/- mice. While loss of GIRK channels attenuated the CCh-induced shortening of action potential duration and suppression of ventricular myocyte excitability, selective ablation of GIRK channels in ventricle had no effect on heart rate, heart rate variability, or electrocardiogram parameters at baseline or after CCh injection. Additionally, loss of ventricular GIRK channels did not impact susceptibility to ventricular arrhythmias. These data suggest that the mouse ventricular GIRK channel is a GIRK1/GIRK4 heteromer, and show that while it contributes to the cholinergic suppression of ventricular myocyte excitability, this influence does not substantially impact cardiac physiology or ventricular arrhythmogenesis in the mouse.
Collapse
|
41
|
Nobles M, Montaigne D, Sebastian S, Birnbaumer L, Tinker A. Differential effects of inhibitory G protein isoforms on G protein-gated inwardly rectifying K + currents in adult murine atria. Am J Physiol Cell Physiol 2018; 314:C616-C626. [PMID: 29342363 DOI: 10.1152/ajpcell.00271.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
G protein-gated inwardly rectifying K+ (GIRK) channels are the major inwardly rectifying K+ currents in cardiac atrial myocytes and an important determinant of atrial electrophysiology. Inhibitory G protein α-subunits can both mediate activation via acetylcholine but can also suppress basal currents in the absence of agonist. We studied this phenomenon using whole cell patch clamping in murine atria from mice with global genetic deletion of Gαi2, combined deletion of Gαi1/Gαi3, and littermate controls. We found that mice with deletion of Gαi2 had increased basal and agonist-activated currents, particularly in the right atria while in contrast those with Gαi1/Gαi3 deletion had reduced currents. Mice with global genetic deletion of Gαi2 had decreased action potential duration. Tissue preparations of the left atria studied with a multielectrode array from Gαi2 knockout mice showed a shorter effective refractory period, with no change in conduction velocity, than littermate controls. Transcriptional studies revealed increased expression of GIRK channel subunit genes in Gαi2 knockout mice. Thus different G protein isoforms have differential effects on GIRK channel behavior and paradoxically Gαi2 act to increase basal and agonist-activated GIRK currents. Deletion of Gαi2 is potentially proarrhythmic in the atria.
Collapse
Affiliation(s)
- Muriel Nobles
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry , London , United Kingdom
| | - David Montaigne
- Centre Hospitalier Régional Universitaire de Lille , Lille , France.,Université Lille 2 , Lille , France.,Institut National de la Santé et de la Recherche Médicale, U1011, Lille , France.,European Genomic Institute for Diabetes , Lille , France.,Institut Pasteur de Lille , Lille , France
| | - Sonia Sebastian
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry , London , United Kingdom
| | - Lutz Birnbaumer
- Division of Intramural Research, National Institute of Environmental Health Sciences , Research Triangle Park, North Carolina.,Institute of Biomedical Research, Catholic University of Argentina , Buenos Aires , Argentina
| | - Andrew Tinker
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry , London , United Kingdom
| |
Collapse
|
42
|
Heijman J, Kirchner D, Kunze F, Chrétien EM, Michel-Reher MB, Voigt N, Knaut M, Michel MC, Ravens U, Dobrev D. Muscarinic type-1 receptors contribute to I K,ACh in human atrial cardiomyocytes and are upregulated in patients with chronic atrial fibrillation. Int J Cardiol 2017; 255:61-68. [PMID: 29290419 DOI: 10.1016/j.ijcard.2017.12.050] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 12/13/2017] [Accepted: 12/19/2017] [Indexed: 01/06/2023]
Abstract
BACKGROUND Basal and acetylcholine-gated inward-rectifier K+-currents (IK1 and IK,ACh, respectively) are altered in atrial fibrillation (AF). Gi-protein-coupled muscarinic (M) receptors type-2 are considered the predominant receptors activating IK,ACh. Although a role for Gq-coupled non-M2-receptor subtypes has been suggested, the precise regulation of IK,ACh by multiple M-receptor subtypes in the human atrium is unknown. Here, we investigated M1-receptor-mediated IK,ACh regulation and its remodeling in chronic AF (cAF). METHODS AND RESULTS M1-receptor mRNA and protein abundance were increased in atrial cardiomyocyte fractions and atrial homogenates from cAF patients, whereas M2-receptor levels were unchanged. The regulation of IK,ACh by M1-receptors was investigated in right-atrial cardiomyocytes using two applications of the M-receptor agonist carbachol (CCh, 2μM), with pharmacological interventions during the second application. CCh application produced a rapid current increase (Peak-IK,ACh), which declined to a quasi-steady-state level (Qss-IK,ACh). In sinus rhythm (Ctl) the selective M1-receptor antagonists pirenzepine (10nM) and muscarinic toxin-7 (MT-7, 10nM) significantly inhibited CCh-activated Peak-IK,ACh, whereas in cAF they significantly reduced both Peak- and Qss-IK,ACh, with no effects on basal inward-rectifier currents in either group. Conversely, the selective M1-receptor agonist McN-A-343 (100μM) induced a current similar to the CCh-activated current in Ctl atrial cardiomyocytes pretreated with pertussis toxin to inhibit M2-receptor-mediated Gi-protein signaling, which was abolished by MT-7. Computational modeling indicated that M1- and M2-receptors redundantly activate IK,ACh to abbreviate APD, albeit with predominant effects of M2-receptors. CONCLUSION Our data suggest that Gq-coupled M1-receptors also regulate human atrial IK,ACh and that their relative contribution to IK,ACh activation is increased in cAF patients. We provide novel insights about the role of non-M2-receptors in human atrial cardiomyocytes, which may have important implications for understanding AF pathophysiology.
Collapse
Affiliation(s)
- Jordi Heijman
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany; Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Dorit Kirchner
- Department of Pharmacology and Toxicology, Carl Gustav Carus Medical Faculty, Dresden University of Technology, Dresden, Germany
| | - Franziska Kunze
- Department of Pharmacology and Toxicology, Carl Gustav Carus Medical Faculty, Dresden University of Technology, Dresden, Germany
| | - Eva Maria Chrétien
- Department of Pharmacology and Toxicology, Carl Gustav Carus Medical Faculty, Dresden University of Technology, Dresden, Germany
| | | | - Niels Voigt
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany
| | - Michael Knaut
- Heart Surgery, Heart Center Dresden, Carl Gustav Carus Medical Faculty, Dresden University of Technology, Dresden, Germany
| | - Martin C Michel
- Department of Pharmacology, Johannes Gutenberg University, Mainz, Germany
| | - Ursula Ravens
- Department of Pharmacology and Toxicology, Carl Gustav Carus Medical Faculty, Dresden University of Technology, Dresden, Germany; Institute of Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Freiburg, Germany
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, Faculty of Medicine, University Duisburg-Essen, Essen, Germany; Department of Pharmacology and Toxicology, Carl Gustav Carus Medical Faculty, Dresden University of Technology, Dresden, Germany.
| |
Collapse
|
43
|
Bébarová M, Horáková Z, Kula R. Addictive drugs, arrhythmias, and cardiac inward rectifiers. Europace 2017; 19:346-355. [PMID: 27302393 DOI: 10.1093/europace/euw071] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 02/20/2016] [Indexed: 12/30/2022] Open
Abstract
In many addictive drugs including alcohol and nicotine, proarrhythmic effects were reported. This review provides an overview of the current knowledge in this field (with a focus on the inward rectifier potassium currents) to promote the lacking data and appeal for their completion, thus, to improve understanding of the proarrhythmic potential of addictive drugs.
Collapse
|
44
|
Jeevaratnam K, Chadda KR, Huang CLH, Camm AJ. Cardiac Potassium Channels: Physiological Insights for Targeted Therapy. J Cardiovasc Pharmacol Ther 2017; 23:119-129. [PMID: 28946759 PMCID: PMC5808825 DOI: 10.1177/1074248417729880] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The development of novel drugs specifically directed at the ion channels underlying particular features of cardiac action potential (AP) initiation, recovery, and refractoriness would contribute to an optimized approach to antiarrhythmic therapy that minimizes potential cardiac and extracardiac toxicity. Of these, K+ channels contribute numerous and diverse currents with specific actions on different phases in the time course of AP repolarization. These features and their site-specific distribution make particular K+ channel types attractive therapeutic targets for the development of pharmacological agents attempting antiarrhythmic therapy in conditions such as atrial fibrillation. However, progress in the development of such temporally and spatially selective antiarrhythmic drugs against particular ion channels has been relatively limited, particularly in view of our incomplete understanding of the complex physiological roles and interactions of the various ionic currents. This review summarizes the physiological properties of the main cardiac potassium channels and the way in which they modulate cardiac electrical activity and then critiques a number of available potential antiarrhythmic drugs directed at them.
Collapse
Affiliation(s)
- Kamalan Jeevaratnam
- 1 Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,2 School of Medicine, Perdana University-Royal College of Surgeons Ireland, Serdang, Selangor Darul Ehsan, Malaysia
| | - Karan R Chadda
- 1 Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,3 Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Christopher L-H Huang
- 3 Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.,4 Division of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - A John Camm
- 5 Cardiac Clinical Academic Group, St George's Hospital Medical School, University of London, Cranmer Terrace, London, United Kingdom
| |
Collapse
|
45
|
Juhász V, Hornyik T, Benák A, Nagy N, Husti Z, Pap R, Sághy L, Virág L, Varró A, Baczkó I. Comparison of the effects of I K,ACh, I Kr, and I Na block in conscious dogs with atrial fibrillation and on action potentials in remodeled atrial trabeculae. Can J Physiol Pharmacol 2017; 96:18-25. [PMID: 28892643 DOI: 10.1139/cjpp-2017-0342] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and a major cause of morbidity and mortality. Traditional antiarrhythmic agents used for restoration of sinus rhythm have limited efficacy in long-term AF and they may possess ventricular proarrhythmic adverse effects, especially in patients with structural heart disease. The acetylcholine receptor-activated potassium channel (IK,ACh) represents an atrial selective target for future AF management. We investigated the effects of the IK,ACh blocker tertiapin-Q (TQ), a derivative of the honeybee toxin tertiapin, on chronic atrial tachypacing-induced AF in conscious dogs, without the influence of anesthetics that modulate a number of cardiac ion channels. Action potentials (APs) were recorded from right atrial trabeculae isolated from dogs with AF. TQ significantly and dose-dependently reduced AF incidence and AF episode duration, prolonged atrial effective refractory period, and prolonged AP duration. The reference drugs propafenone and dofetilide, both used in the clinical management of AF, exerted similar effects against AF in vivo. Dofetilide prolonged atrial AP duration, whereas propafenone increased atrial conduction time. TQ and propafenone did not affect the QT interval, whereas dofetilide prolonged the QT interval. Our results show that inhibition of IK,ACh may represent a novel, atrial-specific target for the management of AF in chronic AF.
Collapse
Affiliation(s)
- Viktor Juhász
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Tibor Hornyik
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Attila Benák
- b 2nd Department of Internal Medicine and Cardiology Centre, University of Szeged, Szeged, Hungary
| | - Norbert Nagy
- c MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - Zoltán Husti
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Róbert Pap
- b 2nd Department of Internal Medicine and Cardiology Centre, University of Szeged, Szeged, Hungary
| | - László Sághy
- b 2nd Department of Internal Medicine and Cardiology Centre, University of Szeged, Szeged, Hungary
| | - László Virág
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - András Varró
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary.,c MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - István Baczkó
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| |
Collapse
|
46
|
Ravens U. Atrial-selective K + channel blockers: potential antiarrhythmic drugs in atrial fibrillation? Can J Physiol Pharmacol 2017; 95:1313-1318. [PMID: 28738160 DOI: 10.1139/cjpp-2017-0024] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In the wake of demographic change in Western countries, atrial fibrillation has reached an epidemiological scale, yet current strategies for drug treatment of the arrhythmia lack sufficient efficacy and safety. In search of novel medications, atrial-selective drugs that specifically target atrial over other cardiac functions have been developed. Here, I will address drugs acting on potassium (K+) channels that are either predominantly expressed in atria or possess electrophysiological properties distinct in atria from ventricles. These channels include the ultra-rapidly activating, delayed outward-rectifying Kv1.5 channel conducting IKur, the acetylcholine-activated inward-rectifying Kir3.1/Kir3.4 channel conducting IK,ACh, the Ca2+-activated K+ channels of small conductance (SK) conducting ISK, and the two-pore domain K+ (K2P) channels (tandem of P domains, weak inward-rectifying K+ channels (TWIK-1), TWIK-related acid-sensitive K+ channels (TASK-1 and TASK-3)) that are responsible for voltage-independent background currents ITWIK-1, ITASK-1, and ITASK-3. Direct drug effects on these channels are described and their putative value in treatment of atrial fibrillation is discussed. Although many potential drug targets have emerged in the process of unravelling details of the pathophysiological mechanisms responsible for atrial fibrillation, we do not know whether novel antiarrhythmic drugs will be more successful when modulating many targets or a single specific one. The answer to this riddle can only be solved in a clinical context.
Collapse
Affiliation(s)
- Ursula Ravens
- Institute of Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, University of Freiburg, Germany; Institute of Physiology, Medical Faculty Carl Gustav Carus, TU Dresden, Germany.,Institute of Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, University of Freiburg, Germany; Institute of Physiology, Medical Faculty Carl Gustav Carus, TU Dresden, Germany
| |
Collapse
|
47
|
Marczenke M, Piccini I, Mengarelli I, Fell J, Röpke A, Seebohm G, Verkerk AO, Greber B. Cardiac Subtype-Specific Modeling of K v1.5 Ion Channel Deficiency Using Human Pluripotent Stem Cells. Front Physiol 2017; 8:469. [PMID: 28729840 PMCID: PMC5498524 DOI: 10.3389/fphys.2017.00469] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Accepted: 06/19/2017] [Indexed: 12/31/2022] Open
Abstract
The ultrarapid delayed rectifier K+ current (IKur), mediated by Kv1.5 channels, constitutes a key component of the atrial action potential. Functional mutations in the underlying KCNA5 gene have been shown to cause hereditary forms of atrial fibrillation (AF). Here, we combine targeted genetic engineering with cardiac subtype-specific differentiation of human induced pluripotent stem cells (hiPSCs) to explore the role of Kv1.5 in atrial hiPSC-cardiomyocytes. CRISPR/Cas9-mediated mutagenesis of integration-free hiPSCs was employed to generate a functional KCNA5 knockout. This model as well as isogenic wild-type control hiPSCs could selectively be differentiated into ventricular or atrial cardiomyocytes at high efficiency, based on the specific manipulation of retinoic acid signaling. Investigation of electrophysiological properties in Kv1.5-deficient cardiomyocytes compared to isogenic controls revealed a strictly atrial-specific disease phentoype, characterized by cardiac subtype-specific field and action potential prolongation and loss of 4-aminopyridine sensitivity. Atrial Kv1.5-deficient cardiomyocytes did not show signs of arrhythmia under adrenergic stress conditions or upon inhibiting additional types of K+ current. Exposure of bulk cultures to carbachol lowered beating frequencies and promoted chaotic spontaneous beating in a stochastic manner. Low-frequency, electrical stimulation in single cells caused atrial and mutant-specific early afterdepolarizations, linking the loss of KCNA5 function to a putative trigger mechanism in familial AF. These results clarify for the first time the role of Kv1.5 in atrial hiPSC-cardiomyocytes and demonstrate the feasibility of cardiac subtype-specific disease modeling using engineered hiPSCs.
Collapse
Affiliation(s)
- Maike Marczenke
- Human Stem Cell Pluripotency Laboratory, Max Planck Institute for Molecular BiomedicineMünster, Germany.,Chemical Genomics Centre of the Max Planck SocietyDortmund, Germany
| | - Ilaria Piccini
- Human Stem Cell Pluripotency Laboratory, Max Planck Institute for Molecular BiomedicineMünster, Germany.,Department of Cardiovascular Medicine, Institute of Genetics of Heart Diseases, University of Münster Medical SchoolMünster, Germany
| | - Isabella Mengarelli
- Department of Clinical and Experimental Cardiology, Academic Medical Center, University of AmsterdamAmsterdam, Netherlands
| | - Jakob Fell
- Human Stem Cell Pluripotency Laboratory, Max Planck Institute for Molecular BiomedicineMünster, Germany.,Chemical Genomics Centre of the Max Planck SocietyDortmund, Germany
| | - Albrecht Röpke
- Institute of Human Genetics, University of MünsterMünster, Germany
| | - Guiscard Seebohm
- Department of Cardiovascular Medicine, Institute of Genetics of Heart Diseases, University of Münster Medical SchoolMünster, Germany
| | - Arie O Verkerk
- Department of Clinical and Experimental Cardiology, Academic Medical Center, University of AmsterdamAmsterdam, Netherlands.,Department of Medical Biology, Academic Medical Center, University of AmsterdamAmsterdam, Netherlands
| | - Boris Greber
- Human Stem Cell Pluripotency Laboratory, Max Planck Institute for Molecular BiomedicineMünster, Germany.,Chemical Genomics Centre of the Max Planck SocietyDortmund, Germany
| |
Collapse
|
48
|
Bao Y, Willis BC, Frasier CR, Lopez-Santiago LF, Lin X, Ramos-Mondragón R, Auerbach DS, Chen C, Wang Z, Anumonwo J, Valdivia HH, Delmar M, Jalife J, Isom LL. Scn2b Deletion in Mice Results in Ventricular and Atrial Arrhythmias. Circ Arrhythm Electrophysiol 2017; 9:CIRCEP.116.003923. [PMID: 27932425 DOI: 10.1161/circep.116.003923] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 11/07/2016] [Indexed: 11/16/2022]
Abstract
BACKGROUND Mutations in SCN2B, encoding voltage-gated sodium channel β2-subunits, are associated with human cardiac arrhythmias, including atrial fibrillation and Brugada syndrome. Because of this, we propose that β2-subunits play critical roles in the establishment or maintenance of normal cardiac electric activity in vivo. METHODS AND RESULTS To understand the pathophysiological roles of β2 in the heart, we investigated the cardiac phenotype of Scn2b null mice. We observed reduced sodium and potassium current densities in ventricular myocytes, as well as conduction slowing in the right ventricular outflow tract region. Functional reentry, resulting from the interplay between slowed conduction, prolonged repolarization, and increased incidence of premature ventricular complexes, was found to underlie the mechanism of spontaneous polymorphic ventricular tachycardia. Scn5a transcript levels were similar in Scn2b null and wild-type ventricles, as were levels of Nav1.5 protein, suggesting that similar to the previous work in neurons, the major function of β2-subunits in the ventricle is to chaperone voltage-gated sodium channel α-subunits to the plasma membrane. Interestingly, Scn2b deletion resulted in region-specific effects in the heart. Scn2b null atria had normal levels of sodium current density compared with wild type. Scn2b null hearts were more susceptible to atrial fibrillation, had increased levels of fibrosis, and higher repolarization dispersion than wild-type littermates. CONCLUSIONS Genetic deletion of Scn2b in mice results in ventricular and atrial arrhythmias, consistent with reported SCN2B mutations in human patients.
Collapse
Affiliation(s)
- Yangyang Bao
- From the Department of Pharmacology, University of Michigan Medical School, Ann Arbor (Y.B., C.R.F., L.F.L.-S., C.C., L.L.I.); Center for Arrhythmia Research and Department of Medicine/Cardiovascular Medicine, University of Michigan, Ann Arbor (B.C.W., R.R.-M., J.A., H.H.V., J.J.); Leon H. Charney Division of Cardiology, New York University School of Medicine, NY (X.L., M.D.); Department of Pharmacology and Physiology, University of Rochester Medical Center, NY (D.S.A.); and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis (Z.W.)
| | - B Cicero Willis
- From the Department of Pharmacology, University of Michigan Medical School, Ann Arbor (Y.B., C.R.F., L.F.L.-S., C.C., L.L.I.); Center for Arrhythmia Research and Department of Medicine/Cardiovascular Medicine, University of Michigan, Ann Arbor (B.C.W., R.R.-M., J.A., H.H.V., J.J.); Leon H. Charney Division of Cardiology, New York University School of Medicine, NY (X.L., M.D.); Department of Pharmacology and Physiology, University of Rochester Medical Center, NY (D.S.A.); and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis (Z.W.)
| | - Chad R Frasier
- From the Department of Pharmacology, University of Michigan Medical School, Ann Arbor (Y.B., C.R.F., L.F.L.-S., C.C., L.L.I.); Center for Arrhythmia Research and Department of Medicine/Cardiovascular Medicine, University of Michigan, Ann Arbor (B.C.W., R.R.-M., J.A., H.H.V., J.J.); Leon H. Charney Division of Cardiology, New York University School of Medicine, NY (X.L., M.D.); Department of Pharmacology and Physiology, University of Rochester Medical Center, NY (D.S.A.); and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis (Z.W.)
| | - Luis F Lopez-Santiago
- From the Department of Pharmacology, University of Michigan Medical School, Ann Arbor (Y.B., C.R.F., L.F.L.-S., C.C., L.L.I.); Center for Arrhythmia Research and Department of Medicine/Cardiovascular Medicine, University of Michigan, Ann Arbor (B.C.W., R.R.-M., J.A., H.H.V., J.J.); Leon H. Charney Division of Cardiology, New York University School of Medicine, NY (X.L., M.D.); Department of Pharmacology and Physiology, University of Rochester Medical Center, NY (D.S.A.); and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis (Z.W.)
| | - Xianming Lin
- From the Department of Pharmacology, University of Michigan Medical School, Ann Arbor (Y.B., C.R.F., L.F.L.-S., C.C., L.L.I.); Center for Arrhythmia Research and Department of Medicine/Cardiovascular Medicine, University of Michigan, Ann Arbor (B.C.W., R.R.-M., J.A., H.H.V., J.J.); Leon H. Charney Division of Cardiology, New York University School of Medicine, NY (X.L., M.D.); Department of Pharmacology and Physiology, University of Rochester Medical Center, NY (D.S.A.); and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis (Z.W.)
| | - Roberto Ramos-Mondragón
- From the Department of Pharmacology, University of Michigan Medical School, Ann Arbor (Y.B., C.R.F., L.F.L.-S., C.C., L.L.I.); Center for Arrhythmia Research and Department of Medicine/Cardiovascular Medicine, University of Michigan, Ann Arbor (B.C.W., R.R.-M., J.A., H.H.V., J.J.); Leon H. Charney Division of Cardiology, New York University School of Medicine, NY (X.L., M.D.); Department of Pharmacology and Physiology, University of Rochester Medical Center, NY (D.S.A.); and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis (Z.W.)
| | - David S Auerbach
- From the Department of Pharmacology, University of Michigan Medical School, Ann Arbor (Y.B., C.R.F., L.F.L.-S., C.C., L.L.I.); Center for Arrhythmia Research and Department of Medicine/Cardiovascular Medicine, University of Michigan, Ann Arbor (B.C.W., R.R.-M., J.A., H.H.V., J.J.); Leon H. Charney Division of Cardiology, New York University School of Medicine, NY (X.L., M.D.); Department of Pharmacology and Physiology, University of Rochester Medical Center, NY (D.S.A.); and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis (Z.W.)
| | - Chunling Chen
- From the Department of Pharmacology, University of Michigan Medical School, Ann Arbor (Y.B., C.R.F., L.F.L.-S., C.C., L.L.I.); Center for Arrhythmia Research and Department of Medicine/Cardiovascular Medicine, University of Michigan, Ann Arbor (B.C.W., R.R.-M., J.A., H.H.V., J.J.); Leon H. Charney Division of Cardiology, New York University School of Medicine, NY (X.L., M.D.); Department of Pharmacology and Physiology, University of Rochester Medical Center, NY (D.S.A.); and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis (Z.W.)
| | - Zhenxun Wang
- From the Department of Pharmacology, University of Michigan Medical School, Ann Arbor (Y.B., C.R.F., L.F.L.-S., C.C., L.L.I.); Center for Arrhythmia Research and Department of Medicine/Cardiovascular Medicine, University of Michigan, Ann Arbor (B.C.W., R.R.-M., J.A., H.H.V., J.J.); Leon H. Charney Division of Cardiology, New York University School of Medicine, NY (X.L., M.D.); Department of Pharmacology and Physiology, University of Rochester Medical Center, NY (D.S.A.); and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis (Z.W.)
| | - Justus Anumonwo
- From the Department of Pharmacology, University of Michigan Medical School, Ann Arbor (Y.B., C.R.F., L.F.L.-S., C.C., L.L.I.); Center for Arrhythmia Research and Department of Medicine/Cardiovascular Medicine, University of Michigan, Ann Arbor (B.C.W., R.R.-M., J.A., H.H.V., J.J.); Leon H. Charney Division of Cardiology, New York University School of Medicine, NY (X.L., M.D.); Department of Pharmacology and Physiology, University of Rochester Medical Center, NY (D.S.A.); and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis (Z.W.)
| | - Héctor H Valdivia
- From the Department of Pharmacology, University of Michigan Medical School, Ann Arbor (Y.B., C.R.F., L.F.L.-S., C.C., L.L.I.); Center for Arrhythmia Research and Department of Medicine/Cardiovascular Medicine, University of Michigan, Ann Arbor (B.C.W., R.R.-M., J.A., H.H.V., J.J.); Leon H. Charney Division of Cardiology, New York University School of Medicine, NY (X.L., M.D.); Department of Pharmacology and Physiology, University of Rochester Medical Center, NY (D.S.A.); and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis (Z.W.)
| | - Mario Delmar
- From the Department of Pharmacology, University of Michigan Medical School, Ann Arbor (Y.B., C.R.F., L.F.L.-S., C.C., L.L.I.); Center for Arrhythmia Research and Department of Medicine/Cardiovascular Medicine, University of Michigan, Ann Arbor (B.C.W., R.R.-M., J.A., H.H.V., J.J.); Leon H. Charney Division of Cardiology, New York University School of Medicine, NY (X.L., M.D.); Department of Pharmacology and Physiology, University of Rochester Medical Center, NY (D.S.A.); and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis (Z.W.)
| | - José Jalife
- From the Department of Pharmacology, University of Michigan Medical School, Ann Arbor (Y.B., C.R.F., L.F.L.-S., C.C., L.L.I.); Center for Arrhythmia Research and Department of Medicine/Cardiovascular Medicine, University of Michigan, Ann Arbor (B.C.W., R.R.-M., J.A., H.H.V., J.J.); Leon H. Charney Division of Cardiology, New York University School of Medicine, NY (X.L., M.D.); Department of Pharmacology and Physiology, University of Rochester Medical Center, NY (D.S.A.); and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis (Z.W.)
| | - Lori L Isom
- From the Department of Pharmacology, University of Michigan Medical School, Ann Arbor (Y.B., C.R.F., L.F.L.-S., C.C., L.L.I.); Center for Arrhythmia Research and Department of Medicine/Cardiovascular Medicine, University of Michigan, Ann Arbor (B.C.W., R.R.-M., J.A., H.H.V., J.J.); Leon H. Charney Division of Cardiology, New York University School of Medicine, NY (X.L., M.D.); Department of Pharmacology and Physiology, University of Rochester Medical Center, NY (D.S.A.); and Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis (Z.W.).
| |
Collapse
|
49
|
Chiamvimonvat N, Chen-Izu Y, Clancy CE, Deschenes I, Dobrev D, Heijman J, Izu L, Qu Z, Ripplinger CM, Vandenberg JI, Weiss JN, Koren G, Banyasz T, Grandi E, Sanguinetti MC, Bers DM, Nerbonne JM. Potassium currents in the heart: functional roles in repolarization, arrhythmia and therapeutics. J Physiol 2017; 595:2229-2252. [PMID: 27808412 DOI: 10.1113/jp272883] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 10/11/2016] [Indexed: 12/19/2022] Open
Abstract
This is the second of the two White Papers from the fourth UC Davis Cardiovascular Symposium Systems Approach to Understanding Cardiac Excitation-Contraction Coupling and Arrhythmias (3-4 March 2016), a biennial event that brings together leading experts in different fields of cardiovascular research. The theme of the 2016 symposium was 'K+ channels and regulation', and the objectives of the conference were severalfold: (1) to identify current knowledge gaps; (2) to understand what may go wrong in the diseased heart and why; (3) to identify possible novel therapeutic targets; and (4) to further the development of systems biology approaches to decipher the molecular mechanisms and treatment of cardiac arrhythmias. The sessions of the Symposium focusing on the functional roles of the cardiac K+ channel in health and disease, as well as K+ channels as therapeutic targets, were contributed by Ye Chen-Izu, Gideon Koren, James Weiss, David Paterson, David Christini, Dobromir Dobrev, Jordi Heijman, Thomas O'Hara, Crystal Ripplinger, Zhilin Qu, Jamie Vandenberg, Colleen Clancy, Isabelle Deschenes, Leighton Izu, Tamas Banyasz, Andras Varro, Heike Wulff, Eleonora Grandi, Michael Sanguinetti, Donald Bers, Jeanne Nerbonne and Nipavan Chiamvimonvat as speakers and panel discussants. This article summarizes state-of-the-art knowledge and controversies on the functional roles of cardiac K+ channels in normal and diseased heart. We endeavour to integrate current knowledge at multiple scales, from the single cell to the whole organ levels, and from both experimental and computational studies.
Collapse
Affiliation(s)
- Nipavan Chiamvimonvat
- Department of Internal Medicine, University of California, Davis, Genome and Biomedical Science Facility, Rm 6315, Davis, CA, 95616, USA.,Department of Veterans Affairs, Northern California Health Care System, Mather, CA, 95655, USA
| | - Ye Chen-Izu
- Department of Internal Medicine, University of California, Davis, Genome and Biomedical Science Facility, Rm 6315, Davis, CA, 95616, USA.,Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA.,Department of Biomedical Engineering, University of California, Davis, Genome and Biomedical Science Facility, Rm 2303, Davis, CA, 95616, USA
| | - Colleen E Clancy
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Isabelle Deschenes
- Department of Physiology and Biophysics, and Biomedical Engineering, Case Western Reserve University, Cleveland, OH, 44109, USA.,Heart and Vascular Research Center, MetroHealth Medical Center, Cleveland, OH, 44109, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Hufelandstrasse 55, 45122, Essen, Germany
| | - Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Leighton Izu
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Zhilin Qu
- Division of Cardiology, Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, 3645 MRL, Los Angeles, CA, 90095, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Jamie I Vandenberg
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, NSW, 2010, Australia
| | - James N Weiss
- Division of Cardiology, Cardiovascular Research Laboratory, David Geffen School of Medicine at UCLA, 3645 MRL, Los Angeles, CA, 90095, USA
| | - Gideon Koren
- Cardiovascular Research Center, Rhode Island Hospital and the Cardiovascular Institute, The Warren Alpert Medical School of Brown University, Providence, RI, 02903, USA
| | - Tamas Banyasz
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Michael C Sanguinetti
- Department of Internal Medicine, University of Utah, Nora Eccles Harrison Cardiovascular Research & Training Institute, Salt Lake City, UT, 84112, USA
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, Genome and Biomedical Science Facility, Rm 3503, Davis, CA, 95616, USA
| | - Jeanne M Nerbonne
- Departments of Developmental Biology and Internal Medicine, Cardiovascular Division, Washington University Medical School, St Louis, MO, 63110, USA
| |
Collapse
|
50
|
Abstract
Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.
Collapse
Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| |
Collapse
|