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Lang D, Ni H, Medvedev RY, Liu F, Alvarez-Baron CP, Tyan L, Turner DGP, Warden A, Morotti S, Schrauth TA, Rickert C, Proenza C, Chanda B, Kamp TJ, Robertson GA, Grandi E, Glukhov AV. WITHDRAWN: Caveolar Compartmentalization is Required for Stable Rhythmicity of Sinus Nodal Cells and is Disrupted in Heart Failure. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.14.589457. [PMID: 38659841 PMCID: PMC11042225 DOI: 10.1101/2024.04.14.589457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
The authors have withdrawn their manuscript owing to technical concerns merged during peer review. Therefore, the authors do not wish this work to be cited as a reference. If you have any questions, please contact the corresponding author.
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Lei M, Salvage SC, Jackson AP, Huang CLH. Cardiac arrhythmogenesis: roles of ion channels and their functional modification. Front Physiol 2024; 15:1342761. [PMID: 38505707 PMCID: PMC10949183 DOI: 10.3389/fphys.2024.1342761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 01/22/2024] [Indexed: 03/21/2024] Open
Abstract
Cardiac arrhythmias cause significant morbidity and mortality and pose a major public health problem. They arise from disruptions in the normally orderly propagation of cardiac electrophysiological activation and recovery through successive cardiomyocytes in the heart. They reflect abnormalities in automaticity, initiation, conduction, or recovery in cardiomyocyte excitation. The latter properties are dependent on surface membrane electrophysiological mechanisms underlying the cardiac action potential. Their disruption results from spatial or temporal instabilities and heterogeneities in the generation and propagation of cellular excitation. These arise from abnormal function in their underlying surface membrane, ion channels, and transporters, as well as the interactions between them. The latter, in turn, form common regulatory targets for the hierarchical network of diverse signaling mechanisms reviewed here. In addition to direct molecular-level pharmacological or physiological actions on these surface membrane biomolecules, accessory, adhesion, signal transduction, and cytoskeletal anchoring proteins modify both their properties and localization. At the cellular level of excitation-contraction coupling processes, Ca2+ homeostatic and phosphorylation processes affect channel activity and membrane excitability directly or through intermediate signaling. Systems-level autonomic cellular signaling exerts both acute channel and longer-term actions on channel expression. Further upstream intermediaries from metabolic changes modulate the channels both themselves and through modifying Ca2+ homeostasis. Finally, longer-term organ-level inflammatory and structural changes, such as fibrotic and hypertrophic remodeling, similarly can influence all these physiological processes with potential pro-arrhythmic consequences. These normal physiological processes may target either individual or groups of ionic channel species and alter with particular pathological conditions. They are also potentially alterable by direct pharmacological action, or effects on longer-term targets modifying protein or cofactor structure, expression, or localization. Their participating specific biomolecules, often clarified in experimental genetically modified models, thus constitute potential therapeutic targets. The insights clarified by the physiological and pharmacological framework outlined here provide a basis for a recent modernized drug classification. Together, they offer a translational framework for current drug understanding. This would facilitate future mechanistically directed therapeutic advances, for which a number of examples are considered here. The latter are potentially useful for treating cardiac, in particular arrhythmic, disease.
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Affiliation(s)
- Ming Lei
- Department of Pharmacology, University of Oxford, Oxford, United Kingdom
| | - Samantha C. Salvage
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Antony P. Jackson
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Christopher L.-H. Huang
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
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Pereira CH, Bare DJ, Rosas PC, Dias FAL, Banach K. The role of P21-activated kinase (Pak1) in sinus node function. J Mol Cell Cardiol 2023; 179:90-101. [PMID: 37086972 PMCID: PMC10294268 DOI: 10.1016/j.yjmcc.2023.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 04/11/2023] [Accepted: 04/11/2023] [Indexed: 04/24/2023]
Abstract
Sinoatrial node (SAN) dysfunction (SND) and atrial arrhythmia frequently occur simultaneously with a hazard ratio of 4.2 for new onset atrial fibrillation (AF) in SND patients. In the atrial muscle attenuated activity of p21-activated kinase 1 (Pak1) increases the risk for AF by enhancing NADPH oxidase 2 dependent production of reactive oxygen species (ROS). However, the role of Pak1 dependent ROS regulation in SAN function has not yet been determined. We hypothesize that Pak1 activity maintains SAN activity by regulating the expression of the hyperpolarization activated cyclic nucleotide gated cation channel (HCN). To determine Pak1 dependent changes in heart rate (HR) regulation we quantified the intrinsic sinus rhythm in wild type (WT) and Pak1 deficient (Pak1-/-) mice of both sexes in vivo and in isolated Langendorff perfused hearts. Pak1-/- hearts displayed an attenuated HR in vivo after autonomic blockage and in isolated hearts. The contribution of the Ca2+ clock to pacemaker activity remained unchanged, but Ivabradine (3 μM), a blocker of HCN channels that are a membrane clock component, eliminated the differences in SAN activity between WT and Pak1-/- hearts. Reduced HCN4 expression was confirmed in Pak1-/- right atria. The reduced HCN activity in Pak1-/- could be rescued by class II HDAC inhibition (LMK235), ROS scavenging (TEMPOL) or attenuation of Extracellular Signal-Regulated Kinase (ERK) 1/2 activity (SCH772984). No sex specific differences in Pak1 dependent SAN regulation were determined. Our results establish Pak1 as a class II HDAC regulator and a potential therapeutic target to attenuate SAN bradycardia and AF susceptibility.
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Affiliation(s)
- Carlos H Pereira
- Dept. of Internal Medicine/Cardiology, Rush University Medical Center, 1750 W. Harrison St., Chicago, IL 60612, USA; Biological Science Center, Department of Physiology, Av. Cel Francisco H. dos Santos 100, 19031 Centro Politécnico-Curitiba, Brazil.
| | - Dan J Bare
- Dept. of Physiology & Biophysics, The Ohio State University, 5018 Graves Hall, 333 W.10th Ave., Columbus, OH 4321, USA.
| | - Paola C Rosas
- Dept. of Pharmacy Practice, College of Pharmacy, 833 S Wood St., Chicago, IL 60612, USA.
| | - Fernando A L Dias
- Biological Science Center, Department of Physiology, Av. Cel Francisco H. dos Santos 100, 19031 Centro Politécnico-Curitiba, Brazil.
| | - Kathrin Banach
- Dept. of Internal Medicine/Cardiology, Rush University Medical Center, 1750 W. Harrison St., Chicago, IL 60612, USA.
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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.
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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
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5
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Yoon J, Daneshgar N, Chu Y, Chen B, Hefti M, Vikram A, Irani K, Song L, Brenner C, Abel ED, London B, Dai D. Metabolic rescue ameliorates mitochondrial encephalo-cardiomyopathy in murine and human iPSC models of Leigh syndrome. Clin Transl Med 2022; 12:e954. [PMID: 35872650 PMCID: PMC9309541 DOI: 10.1002/ctm2.954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 06/09/2022] [Accepted: 06/15/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Mice with deletion of complex I subunit Ndufs4 develop mitochondrial encephalomyopathy resembling Leigh syndrome (LS). The metabolic derangement and underlying mechanisms of cardio-encephalomyopathy in LS remains incompletely understood. METHODS We performed echocardiography, electrophysiology, confocal microscopy, metabolic and molecular/morphometric analysis of the mice lacking Ndufs4. HEK293 cells, human iPS cells-derived cardiomyocytes and neurons were used to determine the mechanistic role of mitochondrial complex I deficiency. RESULTS LS mice develop severe cardiac bradyarrhythmia and diastolic dysfunction. Human-induced pluripotent stem cell-derived cardiomyocytes (iPS-CMs) with Ndufs4 deletion recapitulate LS cardiomyopathy. Mechanistically, we demonstrate a direct link between complex I deficiency, decreased intracellular (nicotinamide adenine dinucleotide) NAD+ /NADH and bradyarrhythmia, mediated by hyperacetylation of the cardiac sodium channel NaV 1.5, particularly at K1479 site. Neuronal apoptosis in the cerebellar and midbrain regions in LS mice was associated with hyperacetylation of p53 and activation of microglia. Targeted metabolomics revealed increases in several amino acids and citric acid cycle intermediates, likely due to impairment of NAD+ -dependent dehydrogenases, and a substantial decrease in reduced Glutathione (GSH). Metabolic rescue by nicotinamide riboside (NR) supplementation increased intracellular NAD+ / NADH, restored metabolic derangement, reversed protein hyperacetylation through NAD+ -dependent Sirtuin deacetylase, and ameliorated cardiomyopathic phenotypes, concomitant with improvement of NaV 1.5 current and SERCA2a function measured by Ca2+ -transients. NR also attenuated neuronal apoptosis and microglial activation in the LS brain and human iPS-derived neurons with Ndufs4 deletion. CONCLUSIONS Our study reveals direct mechanistic explanations of the observed cardiac bradyarrhythmia, diastolic dysfunction and neuronal apoptosis in mouse and human induced pluripotent stem cells (iPSC) models of LS.
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Affiliation(s)
- Jin‐Young Yoon
- Division of Cardiovascular Medicine, Department of Internal MedicineUniversity of Iowa Carver College of MedicineIowa CityIowaUSA
- Abboud Cardiovascular Research Center, University of Iowa Carver College of MedicineIowa CityIowaUSA
| | - Nastaran Daneshgar
- Department of Pathology, Carver College of MedicineUniversity of IowaIowa CityIowaUSA
| | - Yi Chu
- Department of Pathology, Carver College of MedicineUniversity of IowaIowa CityIowaUSA
| | - Biyi Chen
- Division of Cardiovascular Medicine, Department of Internal MedicineUniversity of Iowa Carver College of MedicineIowa CityIowaUSA
- Abboud Cardiovascular Research Center, University of Iowa Carver College of MedicineIowa CityIowaUSA
| | - Marco Hefti
- Department of Pathology, Carver College of MedicineUniversity of IowaIowa CityIowaUSA
| | - Ajit Vikram
- Division of Cardiovascular Medicine, Department of Internal MedicineUniversity of Iowa Carver College of MedicineIowa CityIowaUSA
| | - Kaikobad Irani
- Division of Cardiovascular Medicine, Department of Internal MedicineUniversity of Iowa Carver College of MedicineIowa CityIowaUSA
- Abboud Cardiovascular Research Center, University of Iowa Carver College of MedicineIowa CityIowaUSA
| | - Long‐Sheng Song
- Division of Cardiovascular Medicine, Department of Internal MedicineUniversity of Iowa Carver College of MedicineIowa CityIowaUSA
- Abboud Cardiovascular Research Center, University of Iowa Carver College of MedicineIowa CityIowaUSA
| | - Charles Brenner
- Department of Diabetes & Cancer MetabolismCity of Hope National Medical CenterDuarteCaliforniaUSA
| | - E. Dale Abel
- Fraternal Order of Eagles Diabetes Research Center and Division of Endocrinology and Metabolism, Department of Internal MedicineUniversity of Iowa Carver College of Medicine, University of IowaIowa CityIowaUSA
| | - Barry London
- Division of Cardiovascular Medicine, Department of Internal MedicineUniversity of Iowa Carver College of MedicineIowa CityIowaUSA
- Abboud Cardiovascular Research Center, University of Iowa Carver College of MedicineIowa CityIowaUSA
| | - Dao‐Fu Dai
- Department of Pathology, Carver College of MedicineUniversity of IowaIowa CityIowaUSA
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Blackwell DJ, Schmeckpeper J, Knollmann BC. Animal Models to Study Cardiac Arrhythmias. Circ Res 2022; 130:1926-1964. [PMID: 35679367 DOI: 10.1161/circresaha.122.320258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cardiac arrhythmias are a significant cause of morbidity and mortality worldwide, accounting for 10% to 15% of all deaths. Although most arrhythmias are due to acquired heart disease, inherited channelopathies and cardiomyopathies disproportionately affect children and young adults. Arrhythmogenesis is complex, involving anatomic structure, ion channels and regulatory proteins, and the interplay between cells in the conduction system, cardiomyocytes, fibroblasts, and the immune system. Animal models of arrhythmia are powerful tools for studying not only molecular and cellular mechanism of arrhythmogenesis but also more complex mechanisms at the whole heart level, and for testing therapeutic interventions. This review summarizes basic and clinical arrhythmia mechanisms followed by an in-depth review of published animal models of genetic and acquired arrhythmia disorders.
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Affiliation(s)
- Daniel J Blackwell
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN
| | - Jeffrey Schmeckpeper
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN
| | - Bjorn C Knollmann
- Vanderbilt Center for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN
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Hackl B, Lukacs P, Ebner J, Pesti K, Haechl N, Földi MC, Lilliu E, Schicker K, Kubista H, Stary-Weinzinger A, Hilber K, Mike A, Todt H, Koenig X. The Bradycardic Agent Ivabradine Acts as an Atypical Inhibitor of Voltage-Gated Sodium Channels. Front Pharmacol 2022; 13:809802. [PMID: 35586063 PMCID: PMC9108390 DOI: 10.3389/fphar.2022.809802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 02/24/2022] [Indexed: 12/19/2022] Open
Abstract
Background and purpose: Ivabradine is clinically administered to lower the heart rate, proposedly by inhibiting hyperpolarization-activated cyclic nucleotide-gated cation channels in the sinoatrial node. Recent evidence suggests that voltage-gated sodium channels (VGSC) are inhibited within the same concentration range. VGSCs are expressed within the sinoatrial node and throughout the conduction system of the heart. A block of these channels thus likely contributes to the established and newly raised clinical indications of ivabradine. We, therefore, investigated the pharmacological action of ivabradine on VGSCs in sufficient detail in order to gain a better understanding of the pro- and anti-arrhythmic effects associated with the administration of this drug. Experimental Approach: Ivabradine was tested on VGSCs in native cardiomyocytes isolated from mouse ventricles and the His-Purkinje system and on human Nav1.5 in a heterologous expression system. We investigated the mechanism of channel inhibition by determining its voltage-, frequency-, state-, and temperature-dependence, complemented by a molecular drug docking to the recent Nav1.5 cryoEM structure. Automated patch-clamp experiments were used to investigate ivabradine-mediated changes in Nav1.5 inactivation parameters and inhibition of different VGSC isoforms. Key results: Ivabradine inhibited VGSCs in a voltage- and frequency-dependent manner, but did not alter voltage-dependence of activation and fast inactivation, nor recovery from fast inactivation. Cardiac (Nav1.5), neuronal (Nav1.2), and skeletal muscle (Nav1.4) VGSC isoforms were inhibited by ivabradine within the same concentration range, as were sodium currents in native cardiomyocytes isolated from the ventricles and the His-Purkinje system. Molecular drug docking suggested an interaction of ivabradine with the classical local anesthetic binding site. Conclusion and Implications: Ivabradine acts as an atypical inhibitor of VGSCs. Inhibition of VGSCs likely contributes to the heart rate lowering effect of ivabradine, in particular at higher stimulation frequencies and depolarized membrane potentials, and to the observed slowing of intra-cardiac conduction. Inhibition of VGSCs in native cardiomyocytes and across channel isoforms may provide a potential basis for the anti-arrhythmic potential as observed upon administration of ivabradine.
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Affiliation(s)
- Benjamin Hackl
- Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Peter Lukacs
- ELKH, Plant Protection Institute, Centre for Agricultural Research, Martonvásár, Hungary
| | - Janine Ebner
- Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Krisztina Pesti
- Department of Biochemistry, ELTE Eötvös Loránd University, Budapest, Hungary
- Semmelweis University, School of Ph.D. Studies, Budapest, Hungary
| | - Nicholas Haechl
- Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Mátyás C Földi
- ELKH, Plant Protection Institute, Centre for Agricultural Research, Martonvásár, Hungary
- Department of Biochemistry, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Elena Lilliu
- Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Klaus Schicker
- Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Helmut Kubista
- Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | | | - Karlheinz Hilber
- Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Arpad Mike
- ELKH, Plant Protection Institute, Centre for Agricultural Research, Martonvásár, Hungary
- Department of Biochemistry, ELTE Eötvös Loránd University, Budapest, Hungary
| | - Hannes Todt
- Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
| | - Xaver Koenig
- Department of Neurophysiology and Neuropharmacology, Medical University of Vienna, Vienna, Austria
- *Correspondence: Xaver Koenig,
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8
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What keeps us ticking? Sinoatrial node mechano-sensitivity: the grandfather clock of cardiac rhythm. Biophys Rev 2021; 13:707-716. [PMID: 34777615 DOI: 10.1007/s12551-021-00831-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2021] [Accepted: 08/17/2021] [Indexed: 01/01/2023] Open
Abstract
The rhythmic and spontaneously generated electrical excitation that triggers the heartbeat originates in the sinoatrial node (SAN). SAN automaticity has been thoroughly investigated, which has uncovered fundamental mechanisms involved in cardiac pacemaking that are generally categorised into two interacting and overlapping systems: the 'membrane' and 'Ca2+ clock'. The principal focus of research has been on these two systems of oscillators, which have been studied primarily in single cells and isolated tissue, experimental preparations that do not consider mechanical factors present in the whole heart. SAN mechano-sensitivity has long been known to be a contributor to SAN pacemaking-both as a driver and regulator of automaticity-but its essential nature has been underappreciated. In this review, following a description of the traditional 'clocks' of SAN automaticity, we describe mechanisms of SAN mechano-sensitivity and its vital role for SAN function, making the argument that the 'mechanics oscillator' is, in fact, the 'grandfather clock' of cardiac rhythm.
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9
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Iop L, Iliceto S, Civieri G, Tona F. Inherited and Acquired Rhythm Disturbances in Sick Sinus Syndrome, Brugada Syndrome, and Atrial Fibrillation: Lessons from Preclinical Modeling. Cells 2021; 10:3175. [PMID: 34831398 PMCID: PMC8623957 DOI: 10.3390/cells10113175] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/03/2021] [Accepted: 11/09/2021] [Indexed: 12/12/2022] Open
Abstract
Rhythm disturbances are life-threatening cardiovascular diseases, accounting for many deaths annually worldwide. Abnormal electrical activity might arise in a structurally normal heart in response to specific triggers or as a consequence of cardiac tissue alterations, in both cases with catastrophic consequences on heart global functioning. Preclinical modeling by recapitulating human pathophysiology of rhythm disturbances is fundamental to increase the comprehension of these diseases and propose effective strategies for their prevention, diagnosis, and clinical management. In silico, in vivo, and in vitro models found variable application to dissect many congenital and acquired rhythm disturbances. In the copious list of rhythm disturbances, diseases of the conduction system, as sick sinus syndrome, Brugada syndrome, and atrial fibrillation, have found extensive preclinical modeling. In addition, the electrical remodeling as a result of other cardiovascular diseases has also been investigated in models of hypertrophic cardiomyopathy, cardiac fibrosis, as well as arrhythmias induced by other non-cardiac pathologies, stress, and drug cardiotoxicity. This review aims to offer a critical overview on the effective ability of in silico bioinformatic tools, in vivo animal studies, in vitro models to provide insights on human heart rhythm pathophysiology in case of sick sinus syndrome, Brugada syndrome, and atrial fibrillation and advance their safe and successful translation into the cardiology arena.
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Affiliation(s)
- Laura Iop
- Department of Cardiac Thoracic Vascular Sciences and Public Health, University of Padua, Via Giustiniani, 2, I-35124 Padua, Italy; (S.I.); (G.C.)
| | | | | | - Francesco Tona
- Department of Cardiac Thoracic Vascular Sciences and Public Health, University of Padua, Via Giustiniani, 2, I-35124 Padua, Italy; (S.I.); (G.C.)
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10
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Takla M, Edling CE, Zhang K, Saadeh K, Tse G, Salvage SC, Huang CL, Jeevaratnam K. Transcriptional profiles of genes related to electrophysiological function in Scn5a +/- murine hearts. Physiol Rep 2021; 9:e15043. [PMID: 34617689 PMCID: PMC8495800 DOI: 10.14814/phy2.15043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 08/13/2021] [Accepted: 08/13/2021] [Indexed: 11/24/2022] Open
Abstract
The Scn5a gene encodes the major pore-forming Nav 1.5 (α) subunit, of the voltage-gated Na+ channel in cardiomyocytes. The key role of Nav 1.5 in action potential initiation and propagation in both atria and ventricles predisposes organisms lacking Scn5a or carrying Scn5a mutations to cardiac arrhythmogenesis. Loss-of-function Nav 1.5 genetic abnormalities account for many cases of the human arrhythmic disorder Brugada syndrome (BrS) and related conduction disorders. A murine model with a heterozygous Scn5a deletion recapitulates many electrophysiological phenotypes of BrS. This study examines the relationships between its Scn5a+/- genotype, resulting transcriptional changes, and the consequent phenotypic presentations of BrS. Of 62 selected protein-coding genes related to cardiomyocyte electrophysiological or homeostatic function, concentrations of mRNA transcribed from 15 differed significantly from wild type (WT). Despite halving apparent ventricular Scn5a transcription heterozygous deletion did not significantly downregulate its atrial expression, raising possibilities of atria-specific feedback mechanisms. Most of the remaining 14 genes whose expression differed significantly between WT and Scn5a+/- animals involved Ca2+ homeostasis specifically in atrial tissue, with no overlap with any ventricular changes. All statistically significant changes in expression were upregulations in the atria and downregulations in the ventricles. This investigation demonstrates the value of future experiments exploring for and clarifying links between transcriptional control of Scn5a and of genes whose protein products coordinate Ca2+ regulation and examining their possible roles in BrS.
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Affiliation(s)
- Michael Takla
- Faculty of Health and Medical ScienceUniversity of SurreyGuildfordUK
- Christ’s CollegeUniversity of CambridgeCambridgeUK
| | | | - Kevin Zhang
- Faculty of Health and Medical ScienceUniversity of SurreyGuildfordUK
- School of MedicineImperial College LondonLondonUK
| | - Khalil Saadeh
- Faculty of Health and Medical ScienceUniversity of SurreyGuildfordUK
- Clinical SchoolUniversity of CambridgeCambridgeUK
| | - Gary Tse
- Faculty of Health and Medical ScienceUniversity of SurreyGuildfordUK
- Second Hospital of Tianjin Medical UniversityTianjinChina
| | | | - Christopher L.‐H. Huang
- Faculty of Health and Medical ScienceUniversity of SurreyGuildfordUK
- Department of BiochemistryUniversity of CambridgeCambridgeUK
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11
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Rivaud MR, Delmar M, Remme CA. Heritable arrhythmia syndromes associated with abnormal cardiac sodium channel function: ionic and non-ionic mechanisms. Cardiovasc Res 2021; 116:1557-1570. [PMID: 32251506 PMCID: PMC7341171 DOI: 10.1093/cvr/cvaa082] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 03/01/2020] [Accepted: 04/01/2020] [Indexed: 12/19/2022] Open
Abstract
The cardiac sodium channel NaV1.5, encoded by the SCN5A gene, is responsible for the fast upstroke of the action potential. Mutations in SCN5A may cause sodium channel dysfunction by decreasing peak sodium current, which slows conduction and facilitates reentry-based arrhythmias, and by enhancing late sodium current, which prolongs the action potential and sets the stage for early afterdepolarization and arrhythmias. Yet, some NaV1.5-related disorders, in particular structural abnormalities, cannot be directly or solely explained on the basis of defective NaV1.5 expression or biophysics. An emerging concept that may explain the large disease spectrum associated with SCN5A mutations centres around the multifunctionality of the NaV1.5 complex. In this alternative view, alterations in NaV1.5 affect processes that are independent of its canonical ion-conducting role. We here propose a novel classification of NaV1.5 (dys)function, categorized into (i) direct ionic effects of sodium influx through NaV1.5 on membrane potential and consequent action potential generation, (ii) indirect ionic effects of sodium influx on intracellular homeostasis and signalling, and (iii) non-ionic effects of NaV1.5, independent of sodium influx, through interactions with macromolecular complexes within the different microdomains of the cardiomyocyte. These indirect ionic and non-ionic processes may, acting alone or in concert, contribute significantly to arrhythmogenesis. Hence, further exploration of these multifunctional effects of NaV1.5 is essential for the development of novel preventive and therapeutic strategies.
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Affiliation(s)
- Mathilde R Rivaud
- Department of Clinical and Experimental Cardiology, Heart Center, Amsterdam UMC (location AMC), University of Amsterdam, Amsterdam Cardiovascular Sciences, Meigberdreef 15, 1105AZ Amsterdam, The Netherlands
| | - Mario Delmar
- The Leon H. Charney Division of Cardiology, New York University School of Medicine, 435 E 30th St, NSB 707, New York, NY 10016, USA
| | - Carol Ann Remme
- Department of Clinical and Experimental Cardiology, Heart Center, Amsterdam UMC (location AMC), University of Amsterdam, Amsterdam Cardiovascular Sciences, Meigberdreef 15, 1105AZ Amsterdam, The Netherlands
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12
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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.
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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
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13
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Wallace MJ, El Refaey M, Mesirca P, Hund TJ, Mangoni ME, Mohler PJ. Genetic Complexity of Sinoatrial Node Dysfunction. Front Genet 2021; 12:654925. [PMID: 33868385 PMCID: PMC8047474 DOI: 10.3389/fgene.2021.654925] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 03/01/2021] [Indexed: 12/13/2022] Open
Abstract
The pacemaker cells of the cardiac sinoatrial node (SAN) are essential for normal cardiac automaticity. Dysfunction in cardiac pacemaking results in human sinoatrial node dysfunction (SND). SND more generally occurs in the elderly population and is associated with impaired pacemaker function causing abnormal heart rhythm. Individuals with SND have a variety of symptoms including sinus bradycardia, sinus arrest, SAN block, bradycardia/tachycardia syndrome, and syncope. Importantly, individuals with SND report chronotropic incompetence in response to stress and/or exercise. SND may be genetic or secondary to systemic or cardiovascular conditions. Current management of patients with SND is limited to the relief of arrhythmia symptoms and pacemaker implantation if indicated. Lack of effective therapeutic measures that target the underlying causes of SND renders management of these patients challenging due to its progressive nature and has highlighted a critical need to improve our understanding of its underlying mechanistic basis of SND. This review focuses on current information on the genetics underlying SND, followed by future implications of this knowledge in the management of individuals with SND.
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Affiliation(s)
- Michael J. Wallace
- Frick Center for Heart Failure and Arrhythmia Research, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Mona El Refaey
- Frick Center for Heart Failure and Arrhythmia Research, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
| | - Pietro Mesirca
- CNRS, INSERM, Institut de Génomique Fonctionnelle, Université de Montpellier, Montpellier, France
- Laboratory of Excellence ICST, Montpellier, France
| | - Thomas J. Hund
- Frick Center for Heart Failure and Arrhythmia Research, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH, United States
| | - Matteo E. Mangoni
- CNRS, INSERM, Institut de Génomique Fonctionnelle, Université de Montpellier, Montpellier, France
- Laboratory of Excellence ICST, Montpellier, France
| | - Peter J. Mohler
- Frick Center for Heart Failure and Arrhythmia Research, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Department of Physiology and Cell Biology, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
- Division of Cardiovascular Medicine, Department of Internal Medicine, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States
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14
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Mesirca P, Fedorov VV, Hund TJ, Torrente AG, Bidaud I, Mohler PJ, Mangoni ME. Pharmacologic Approach to Sinoatrial Node Dysfunction. Annu Rev Pharmacol Toxicol 2021; 61:757-778. [PMID: 33017571 PMCID: PMC7790915 DOI: 10.1146/annurev-pharmtox-031120-115815] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The spontaneous activity of the sinoatrial node initiates the heartbeat. Sino-atrial node dysfunction (SND) and sick sinoatrial (sick sinus) syndrome are caused by the heart's inability to generate a normal sinoatrial node action potential. In clinical practice, SND is generally considered an age-related pathology, secondary to degenerative fibrosis of the heart pacemaker tissue. However, other forms of SND exist, including idiopathic primary SND, which is genetic, and forms that are secondary to cardiovascular or systemic disease. The incidence of SND in the general population is expected to increase over the next half century, boosting the need to implant electronic pacemakers. During the last two decades, our knowledge of sino-atrial node physiology and of the pathophysiological mechanisms underlying SND has advanced considerably. This review summarizes the current knowledge about SND mechanisms and discusses the possibility of introducing new pharmacologic therapies for treating SND.
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Affiliation(s)
- Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34096 Montpellier, France;
- LabEx Ion Channels Science and Therapeutics (ICST), 06560 Nice, France
| | - Vadim V Fedorov
- Frick Center for Heart Failure and Arrhythmia at the Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Physiology and Cell Biology, The Ohio State University College of Medicine, Wexner Medical Center, Columbus, Ohio 43210, USA
| | - Thomas J Hund
- Frick Center for Heart Failure and Arrhythmia at the Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio 43210, USA
| | - Angelo G Torrente
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34096 Montpellier, France;
- LabEx Ion Channels Science and Therapeutics (ICST), 06560 Nice, France
| | - Isabelle Bidaud
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34096 Montpellier, France;
- LabEx Ion Channels Science and Therapeutics (ICST), 06560 Nice, France
| | - Peter J Mohler
- Frick Center for Heart Failure and Arrhythmia at the Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio 43210, USA
- Department of Physiology and Cell Biology, The Ohio State University College of Medicine, Wexner Medical Center, Columbus, Ohio 43210, USA
- Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, Ohio 43210, USA
| | - Matteo E Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34096 Montpellier, France;
- LabEx Ion Channels Science and Therapeutics (ICST), 06560 Nice, France
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15
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Torrente AG, Mesirca P, Bidaud I, Mangoni ME. Channelopathies of voltage-gated L-type Cav1.3/α 1D and T-type Cav3.1/α 1G Ca 2+ channels in dysfunction of heart automaticity. Pflugers Arch 2020; 472:817-830. [PMID: 32601767 DOI: 10.1007/s00424-020-02421-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/12/2020] [Accepted: 06/19/2020] [Indexed: 10/24/2022]
Abstract
The heart automaticity is a fundamental physiological function in vertebrates. The cardiac impulse is generated in the sinus node by a specialized population of spontaneously active myocytes known as "pacemaker cells." Failure in generating or conducting spontaneous activity induces dysfunction in cardiac automaticity. Several families of ion channels are involved in the generation and regulation of the heart automaticity. Among those, voltage-gated L-type Cav1.3 (α1D) and T-type Cav3.1 (α1G) Ca2+ channels play important roles in the spontaneous activity of pacemaker cells. Ca2+ channel channelopathies specifically affecting cardiac automaticity are considered rare. Recent research on familial disease has identified mutations in the Cav1.3-encoding CACNA1D gene that underlie congenital sinus node dysfunction and deafness (OMIM # 614896). In addition, both Cav1.3 and Cav3.1 channels have been identified as pathophysiological targets of sinus node dysfunction and heart block, caused by congenital autoimmune disease of the cardiac conduction system. The discovery of channelopathies linked to Cav1.3 and Cav3.1 channels underscores the importance of Ca2+ channels in the generation and regulation of heart's automaticity.
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Affiliation(s)
- Angelo G Torrente
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx Ion Channels Science and Therapeutics (ICST), Montpellier, France
| | - Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx Ion Channels Science and Therapeutics (ICST), Montpellier, France
| | - Isabelle Bidaud
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 141, rue de la cardonille, 34094, Montpellier, France.,LabEx Ion Channels Science and Therapeutics (ICST), Montpellier, France
| | - Matteo E Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 141, rue de la cardonille, 34094, Montpellier, France. .,LabEx Ion Channels Science and Therapeutics (ICST), Montpellier, France.
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16
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Inhibition of G protein-gated K + channels by tertiapin-Q rescues sinus node dysfunction and atrioventricular conduction in mouse models of primary bradycardia. Sci Rep 2020; 10:9835. [PMID: 32555258 PMCID: PMC7300035 DOI: 10.1038/s41598-020-66673-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 05/21/2020] [Indexed: 02/06/2023] Open
Abstract
Sinus node (SAN) dysfunction (SND) manifests as low heart rate (HR) and is often accompanied by atrial tachycardia or atrioventricular (AV) block. The only currently available therapy for chronic SND is the implantation of an electronic pacemaker. Because of the growing burden of SND in the population, new pharmacological therapies of chronic SND and heart block are desirable. We developed a collection of genetically modified mouse strains recapitulating human primary SND associated with different degrees of AV block. These mice were generated with genetic ablation of L-type Cav1.3 (Cav1.3-/-), T-type Cav3.1 (Cav3.1-/-), or both (Cav1.3-/-/Cav3.1-/-). We also studied mice haplo-insufficient for the Na+ channel Nav1.5 (Nav1.5+/) and mice in which the cAMP-dependent regulation of hyperpolarization-activated f-(HCN4) channels has been abolished (HCN4-CNBD). We analysed, by telemetric ECG recording, whether pharmacological inhibition of the G-protein-activated K+ current (IKACh) by the peptide tertiapin-Q could improve HR and AV conduction in these mouse strains. Tertiapin-Q significantly improved the HR of Cav1.3-/- (19%), Cav1.3-/-/Cav3.1-/- (23%) and HCN4-CNBD (14%) mice. Tertiapin-Q also improved cardiac conduction of Nav1.5+/- mice by 24%. Our data suggest that the development of pharmacological IKACh inhibitors for the management of SND and conduction disease is a viable approach.
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17
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Yan J, Li H, Bu H, Jiao K, Zhang AX, Le T, Cao H, Li Y, Ding Y, Xu X. Aging-associated sinus arrest and sick sinus syndrome in adult zebrafish. PLoS One 2020; 15:e0232457. [PMID: 32401822 PMCID: PMC7219707 DOI: 10.1371/journal.pone.0232457] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 04/15/2020] [Indexed: 12/24/2022] Open
Abstract
Because of its powerful genetics, the adult zebrafish has been increasingly used for studying cardiovascular diseases. Considering its heart rate of ~100 beats per minute at ambient temperature, which is very close to human, we assessed the use of this vertebrate animal for modeling heart rhythm disorders such as sinus arrest (SA) and sick sinus syndrome (SSS). We firstly optimized a protocol to measure electrocardiogram in adult zebrafish. We determined the location of the probes, implemented an open-chest microsurgery procedure, measured the effects of temperature, and determined appropriate anesthesia dose and time. We then proposed an PP interval of more than 1.5 seconds as an arbitrary criterion to define an SA episode in an adult fish at ambient temperature, based on comparison between the current definition of an SA episode in humans and our studies of candidate SA episodes in aged wild-type fish and Tg(SCN5A-D1275N) fish (a fish model for inherited SSS). With this criterion, a subpopulation of about 5% wild-type fish can be considered to have SA episodes, and this percentage significantly increases to about 25% in 3-year-old fish. In response to atropine, this subpopulation has both common SSS phenotypic traits that are shared with the Tg(SCN5A-D1275N) model, such as bradycardia; and unique SSS phenotypic traits, such as increased QRS/P ratio and chronotropic incompetence. In summary, this study defined baseline SA and SSS in adult zebrafish and underscored use of the zebrafish as an alternative model to study aging-associated SSS.
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Affiliation(s)
- Jianhua Yan
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
- Division of Cardiology, Xinhua Hospital Affiliated To Shanghai Jiaotong University School Of Medicine, Shanghai, China
| | - Hongsong Li
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Haisong Bu
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Kunli Jiao
- Division of Cardiology, Xinhua Hospital Affiliated To Shanghai Jiaotong University School Of Medicine, Shanghai, China
| | - Alex X. Zhang
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Tai Le
- Department of Electrical Engineering and Computer Science, UC Irvine, Irvine, California
| | - Hung Cao
- Department of Electrical Engineering and Computer Science, UC Irvine, Irvine, California
- Department of Biomedical Engineering, UC Irvine, Irvine, California
| | - Yigang Li
- Division of Cardiology, Xinhua Hospital Affiliated To Shanghai Jiaotong University School Of Medicine, Shanghai, China
| | - Yonghe Ding
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Xiaolei Xu
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, United States of America
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
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18
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MacDonald EA, Rose RA, Quinn TA. Neurohumoral Control of Sinoatrial Node Activity and Heart Rate: Insight From Experimental Models and Findings From Humans. Front Physiol 2020; 11:170. [PMID: 32194439 PMCID: PMC7063087 DOI: 10.3389/fphys.2020.00170] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 02/13/2020] [Indexed: 12/22/2022] Open
Abstract
The sinoatrial node is perhaps one of the most important tissues in the entire body: it is the natural pacemaker of the heart, making it responsible for initiating each-and-every normal heartbeat. As such, its activity is heavily controlled, allowing heart rate to rapidly adapt to changes in physiological demand. Control of sinoatrial node activity, however, is complex, occurring through the autonomic nervous system and various circulating and locally released factors. In this review we discuss the coupled-clock pacemaker system and how its manipulation by neurohumoral signaling alters heart rate, considering the multitude of canonical and non-canonical agents that are known to modulate sinoatrial node activity. For each, we discuss the principal receptors involved and known intracellular signaling and protein targets, highlighting gaps in our knowledge and understanding from experimental models and human studies that represent areas for future research.
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Affiliation(s)
- Eilidh A. MacDonald
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Robert A. Rose
- Cumming School of Medicine, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | - T. Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
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19
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Li N, Kalyanasundaram A, Hansen BJ, Artiga EJ, Sharma R, Abudulwahed SH, Helfrich KM, Rozenberg G, Wu PJ, Zakharkin S, Gyorke S, Janssen PM, Whitson BA, Mokadam NA, Biesiadecki BJ, Accornero F, Hummel JD, Mohler PJ, Dobrzynski H, Zhao J, Fedorov VV. Impaired neuronal sodium channels cause intranodal conduction failure and reentrant arrhythmias in human sinoatrial node. Nat Commun 2020; 11:512. [PMID: 31980605 PMCID: PMC6981137 DOI: 10.1038/s41467-019-14039-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 12/16/2019] [Indexed: 01/26/2023] Open
Abstract
Mechanisms for human sinoatrial node (SAN) dysfunction are poorly understood and whether human SAN excitability requires voltage-gated sodium channels (Nav) remains controversial. Here, we report that neuronal (n)Nav blockade and selective nNav1.6 blockade during high-resolution optical mapping in explanted human hearts depress intranodal SAN conduction, which worsens during autonomic stimulation and overdrive suppression to conduction failure. Partial cardiac (c)Nav blockade further impairs automaticity and intranodal conduction, leading to beat-to-beat variability and reentry. Multiple nNav transcripts are higher in SAN vs atria; heterogeneous alterations of several isoforms, specifically nNav1.6, are associated with heart failure and chronic alcohol consumption. In silico simulations of Nav distributions suggest that INa is essential for SAN conduction, especially in fibrotic failing hearts. Our results reveal that not only cNav but nNav are also integral for preventing disease-induced failure in human SAN intranodal conduction. Disease-impaired nNav may underlie patient-specific SAN dysfunctions and should be considered to treat arrhythmias. The role of of voltage-gated sodium channels (Nav) in pacemaking and conduction of the human sinoatrial node is unclear. Here, the authors investigate existence and function of neuronal and cardiac Nav in human sinoatrial nodes, and demonstrate their alterations in explanted human diseased hearts.
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Affiliation(s)
- Ning Li
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Anuradha Kalyanasundaram
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Brian J Hansen
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Esthela J Artiga
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Roshan Sharma
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Suhaib H Abudulwahed
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Katelynn M Helfrich
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Galina Rozenberg
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Pei-Jung Wu
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Stanislav Zakharkin
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Sandor Gyorke
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Paul Ml Janssen
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Bryan A Whitson
- Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Department of Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Nahush A Mokadam
- Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Department of Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Brandon J Biesiadecki
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Federica Accornero
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - John D Hummel
- Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Peter J Mohler
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA.,Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Halina Dobrzynski
- Division of Cardiovascular Sciences, The University of Manchester, Manchester, UK.,Department of Anatomy, Jagiellonian University Medical College, Cracow, Poland
| | - Jichao Zhao
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Vadim V Fedorov
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, Columbus, OH, USA. .,Bob and Corrine Frick Center for Heart Failure and Arrhythmia, Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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20
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Ahmad S, Valli H, Smyth R, Jiang AY, Jeevaratnam K, Matthews HR, Huang CL. Reduced cardiomyocyte Na + current in the age-dependent murine Pgc-1β -/- model of ventricular arrhythmia. J Cell Physiol 2019; 234:3921-3932. [PMID: 30146680 PMCID: PMC6492124 DOI: 10.1002/jcp.27183] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 07/12/2018] [Indexed: 12/27/2022]
Abstract
Peroxisome proliferator-activated receptor-γ coactivator-1 deficient (Pgc-1β-/- ) murine hearts model the increased, age-dependent, ventricular arrhythmic risks attributed to clinical conditions associated with mitochondrial energetic dysfunction. These were accompanied by compromised action potential (AP) upstroke rates and impaired conduction velocities potentially producing arrhythmic substrate. We tested a hypothesis implicating compromised Na+ current in these electrophysiological phenotypes by applying loose patch-clamp techniques in intact young and aged, wild-type (WT) and Pgc-1β-/- , ventricular cardiomyocyte preparations for the first time. This allowed conservation of their in vivo extracellular and intracellular conditions. Depolarising steps elicited typical voltage-dependent activating and inactivating inward Na+ currents with peak amplitudes increasing or decreasing with their respective activating or preceding inactivating voltage steps. Two-way analysis of variance associated Pgc-1β-/- genotype with independent reductions in maximum peak ventricular Na+ currents from -36.63 ± 2.14 (n = 20) and -35.43 ± 1.96 (n = 18; young and aged WT, respectively), to -29.06 ± 1.65 (n = 23) and -27.93 ± 1.63 (n = 20; young and aged Pgc-1β-/- , respectively) pA/μm2 (p < 0.0001), without independent effects of, or interactions with age. Voltages at half-maximal current V*, and steepness factors k in plots of voltage dependences of both Na+ current activation and inactivation, and time constants for its postrepolarisation recovery from inactivation, remained indistinguishable through all experimental groups. So were the activation and rectification properties of delayed outward (K+ ) currents, demonstrated from tail currents reflecting current recoveries from respective varying or constant voltage steps. These current-voltage properties directly implicate decreases specifically in maximum available Na+ current with unchanged voltage dependences and unaltered K+ current properties, in proarrhythmic reductions in AP conduction velocity in Pgc-1β-/- ventricles.
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Affiliation(s)
- Shiraz Ahmad
- Physiological LaboratoryUniversity of CambridgeCambridgeUnited Kingdom
| | - Haseeb Valli
- Physiological LaboratoryUniversity of CambridgeCambridgeUnited Kingdom
| | - Robert Smyth
- Physiological LaboratoryUniversity of CambridgeCambridgeUnited Kingdom
| | - Anita Y. Jiang
- Physiological LaboratoryUniversity of CambridgeCambridgeUnited Kingdom
| | - Kamalan Jeevaratnam
- Physiological LaboratoryUniversity of CambridgeCambridgeUnited Kingdom
- Department of Veterinary Pre‐clinical Sciences, Faculty of Health and Medical SciencesUniversity of SurreyGuildfordUnited Kingdom
- Department of Physiology, PU‐RCSI School of Medicine, Perdana UniversitySerdangMalaysia
| | - Hugh R. Matthews
- Physiological LaboratoryUniversity of CambridgeCambridgeUnited Kingdom
| | - Christopher L.‐H. Huang
- Physiological LaboratoryUniversity of CambridgeCambridgeUnited Kingdom
- Department of BiochemistryUniversity of CambridgeCambridgeUnited Kingdom
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21
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Natriuretic Peptide Receptor-C Protects Against Angiotensin II-Mediated Sinoatrial Node Disease in Mice. JACC Basic Transl Sci 2018; 3:824-843. [PMID: 30623142 PMCID: PMC6314975 DOI: 10.1016/j.jacbts.2018.08.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 08/15/2018] [Accepted: 08/16/2018] [Indexed: 12/19/2022]
Abstract
SAN disease is prevalent in hypertension and heart failure and can be induced by chronic Ang II treatment in mice. Ang II caused SAN disease in mice in association with impaired electrical conduction, reduction in the hyperpolarization-activated current (If) in SAN myocytes, and increased SAN fibrosis. Ang II-induced SAN disease was worsened in mice lacking NPR-C in association with enhanced SAN fibrosis. Mice co-treated with Ang II and an NPR-C agonist (cANF) were protected from SAN disease. NPR-C may represent a new target to protect against Ang II-induced SAN disease.
Sinoatrial node (SAN) disease mechanisms are poorly understood, and therapeutic options are limited. Natriuretic peptide(s) (NP) are cardioprotective hormones whose effects can be mediated partly by the NP receptor C (NPR-C). We investigated the role of NPR-C in angiotensin II (Ang II)-mediated SAN disease in mice. Ang II caused SAN disease due to impaired electrical activity in SAN myocytes and increased SAN fibrosis. Strikingly, Ang II treatment in NPR-C−/− mice worsened SAN disease, whereas co-treatment of wild-type mice with Ang II and a selective NPR-C agonist (cANF) prevented SAN dysfunction. NPR-C may represent a new target to protect against the development of Ang II-induced SAN disease.
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Key Words
- AP, action potential
- Ang II, angiotensin II
- CV, conduction velocity
- DD, diastolic depolarization
- Gmax, maximum conductance
- HR, heart rate
- ICa,L, L-type calcium current
- ICa,T, T-type calcium current
- INCX, sodium–calcium exchanger current
- IV, current voltage relationship
- If, hyperpolarization-activated current
- NP, natriuretic peptide
- NPR, natriuretic peptide receptor
- NPR-C, natriuretic peptide receptor C
- SAN, sinoatrial node
- SBP, systolic blood pressure
- V1/2(act), voltage for 50% channel activation
- cSNRT, corrected sinoatrial node recovery time
- fibrosis
- hypertension
- ion currents
- natriuretic peptide
- sinoatrial node
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Chadda KR, Edling CE, Valli H, Ahmad S, Huang CLH, Jeevaratnam K. Gene and Protein Expression Profile of Selected Molecular Targets Mediating Electrophysiological Function in Pgc-1α Deficient Murine Atria. Int J Mol Sci 2018; 19:ijms19113450. [PMID: 30400228 PMCID: PMC6274828 DOI: 10.3390/ijms19113450] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 10/25/2018] [Accepted: 10/29/2018] [Indexed: 12/27/2022] Open
Abstract
Increases in the prevalence of obesity, insulin resistance, and metabolic syndrome has led to the increase of atrial fibrillation (AF) cases in the developed world. These AF risk factors are associated with mitochondrial dysfunction, previously modelled using peroxisome proliferator activated receptor-γ (PPARγ) coactivator-1 (Pgc-1)-deficient murine cardiac models. We explored gene and protein expression profiles of selected molecular targets related to electrophysiological function in murine Pgc-1α−/− atria. qPCR analysis surveyed genes related to Na+-K+-ATPase, K+ conductance, hyperpolarisation-activated cyclic nucleotide-gated (Hcn), Na+ channels, Ca2+ channels, and indicators for adrenergic and cholinergic receptor modulation. Western blot analysis for molecular targets specific to conduction velocity (Nav1.5 channel and gap junctions) was performed. Transcription profiles revealed downregulation of molecules related to Na+-K+-ATPase transport, Hcn-dependent pacemaker function, Na+ channel-dependent action potential activation and propagation, Ca2+ current generation, calsequestrin-2 dependent Ca2+ homeostasis, and adrenergic α1D dependent protection from hypertrophic change. Nav1.5 channel protein expression but not gap junction expression was reduced in Pgc-1α−/− atria compared to WT. Nav1.5 reduction reflects corresponding reduction in its gene expression profile. These changes, as well as the underlying Pgc-1α−/− alteration, suggest potential pharmacological targets directed towards either upstream PGC-1 signalling mechanisms or downstream ion channel changes.
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Affiliation(s)
- Karan R Chadda
- Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7AL, UK.
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK.
| | - Charlotte E Edling
- Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7AL, UK.
| | - Haseeb Valli
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK.
| | - Shiraz Ahmad
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK.
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK.
- Department of Biochemistry, Hopkins Building, University of Cambridge, Cambridge CB2 1QW, UK.
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7AL, UK.
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK.
- School of Medicine, Perdana University-Royal College of Surgeons Ireland, Serdang 43400, Malaysia.
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23
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Wilde AAM, Amin AS. Clinical Spectrum of SCN5A Mutations: Long QT Syndrome, Brugada Syndrome, and Cardiomyopathy. JACC Clin Electrophysiol 2018; 4:569-579. [PMID: 29798782 DOI: 10.1016/j.jacep.2018.03.006] [Citation(s) in RCA: 186] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 03/02/2018] [Accepted: 03/08/2018] [Indexed: 12/13/2022]
Abstract
SCN5A gene encodes the pore-forming ion-conducting α-subunit of the cardiac sodium channel (Nav1.5), which is responsible for the initiation and propagation of action potentials and thereby determines cardiac excitability and conduction of electrical stimuli through the heart. The importance of Nav1.5 for normal cardiac electricity is reflected by various disease entities that can be caused by mutations in SCN5A. Gain-of-function mutations in SCN5A lead to more sodium influx into cardiomyocytes through aberrant channel gating and cause long QT syndrome, a primary electrical disease of the heart. Loss-of-function mutations in SCN5A lead to lower expression levels of SCN5A or production of defective Nav1.5 proteins and cause Brugada syndrome, an electrical disease with minor structural changes in the heart. In addition, both loss- and gain-of-function mutations may cause dilated cardiomyopathy, which is an arrhythmogenic disease with gross structural defects of the left ventricle (and sometimes both ventricles). Other SCN5A-related diseases are multifocal ectopic premature Purkinje-related complexes (gain-of-function mutations), isolated cardiac conduction defect (loss-of-function mutations), sick sinus syndrome (loss-of-function mutations), atrial fibrillation (loss-of-function or gain-of-function mutations), and overlap syndromes (mutations with both loss-of-function and gain-of-function effects). Growing insights into the role of SCN5A in health and disease has enabled clinicians to lay out gene-specific risk stratification schemes and mutation-specific diagnostic and therapeutic strategies in the management of patients with a SCN5A mutation. This review summarizes currently available knowledge about the pathophysiological mechanisms of SCN5A mutations and describes how this knowledge can be used to manage patients suffering from potentially lethal cardiac diseases.
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Affiliation(s)
- Arthur A M Wilde
- Heart Centre Academic Medical Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; Princess Al-Jawhara Al-Brahim Centre of Excellence in Research of Hereditary Disorders, Jeddah, Kingdom of Saudi Arabia; Department of Medicine, Columbia University Irving Medical Centre, New York, New York.
| | - Ahmad S Amin
- Heart Centre Academic Medical Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
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Valli H, Ahmad S, Sriharan S, Dean LD, Grace AA, Jeevaratnam K, Matthews HR, Huang CLH. Epac-induced ryanodine receptor type 2 activation inhibits sodium currents in atrial and ventricular murine cardiomyocytes. Clin Exp Pharmacol Physiol 2017; 45:278-292. [PMID: 29027245 PMCID: PMC5814738 DOI: 10.1111/1440-1681.12870] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Revised: 09/23/2017] [Accepted: 09/27/2017] [Indexed: 12/16/2022]
Abstract
Acute RyR2 activation by exchange protein directly activated by cAMP (Epac) reversibly perturbs myocyte Ca2+ homeostasis, slows myocardial action potential conduction, and exerts pro‐arrhythmic effects. Loose patch‐clamp studies, preserving in vivo extracellular and intracellular conditions, investigated Na+ current in intact cardiomyocytes in murine atrial and ventricular preparations following Epac activation. Depolarising steps to varying test voltages activated typical voltage‐dependent Na+ currents. Plots of peak current against depolarisation from resting potential gave pretreatment maximum atrial and ventricular currents of −20.23 ± 1.48 (17) and −29.8 ± 2.4 (10) pA/μm2 (mean ± SEM [n]). Challenge by 8‐CPT (1 μmol/L) reduced these currents to −11.21 ± 0.91 (12) (P < .004) and −19.3 ± 1.6 (11) pA/μm2 (P < .04) respectively. Currents following further addition of the RyR2 inhibitor dantrolene (10 μmol/L) (−19.91 ± 2.84 (13) and −26.6 ± 1.7 (17)), and dantrolene whether alone (−19.53 ± 1.97 (8) and −27.6 ± 1.9 (14)) or combined with 8‐CPT (−19.93 ± 2.59 (12) and −29.9 ± 2.5(11)), were indistinguishable from pretreatment values (all P >> .05). Assessment of the inactivation that followed by applying subsequent steps to a fixed voltage 100 mV positive to resting potential gave concordant results. Half‐maximal inactivation voltages and steepness factors, and time constants for Na+ current recovery from inactivation in double‐pulse experiments, were similar through all the pharmacological conditions. Intracellular sharp microelectrode membrane potential recordings in intact Langendorff‐perfused preparations demonstrated concordant variations in maximum rates of atrial and ventricular action potential upstroke, (dV/dt)max. We thus demonstrate an acute, reversible, Na+ channel inhibition offering a possible mechanism for previously reported pro‐arrhythmic slowing of AP propagation following modifications of Ca2+ homeostasis, complementing earlier findings from chronic alterations in Ca2+ homeostasis in genetically‐modified RyR2‐P2328S hearts.
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Affiliation(s)
- Haseeb Valli
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Shiraz Ahmad
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Sujan Sriharan
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Lydia D Dean
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Andrew A Grace
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Kamalan Jeevaratnam
- Physiological Laboratory, University of Cambridge, Cambridge, UK.,Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK.,PU-RCSI School of Medicine, Perdana University, Serdang, Selangor Darul Ehsan, Malaysia
| | - Hugh R Matthews
- Physiological Laboratory, University of Cambridge, Cambridge, UK
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Cambridge, UK.,Department of Biochemistry, University of Cambridge, Cambridge, UK
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25
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Valli H, Ahmad S, Jiang AY, Smyth R, Jeevaratnam K, Matthews HR, Huang CLH. Cardiomyocyte ionic currents in intact young and aged murine Pgc-1β -/- atrial preparations. Mech Ageing Dev 2017; 169:1-9. [PMID: 29197478 PMCID: PMC5846848 DOI: 10.1016/j.mad.2017.11.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 11/11/2017] [Accepted: 11/28/2017] [Indexed: 12/19/2022]
Abstract
Energetically-deficient Pgc-1β−/− murine atria show age-dependent arrhythmia. Voltage clamp studies investigated their underlying membrane current changes. Pgc-1β−/− atria showed reduced inward Na+ currents with normal voltage-dependences. Outward repolarising K+ currents retained normal activation and rectification. A resulting slowed action potential conduction explains the arrhythmic phenotype.
Introduction Recent studies reported that energetically deficient murine Pgc-1β−/− hearts replicate age-dependent atrial arrhythmic phenotypes associated with their corresponding clinical conditions, implicating action potential (AP) conduction slowing consequent upon reduced AP upstroke rates. Materials and methods We tested a hypothesis implicating Na+ current alterations as a mechanism underlying these electrophysiological phenotypes. We applied loose patch-clamp techniques to intact young and aged, WT and Pgc-1β−/−, atrial cardiomyocyte preparations preserving their in vivo extracellular and intracellular conditions. Results and discussion Depolarising steps activated typical voltage-dependent activating and inactivating inward (Na+) currents whose amplitude increased or decreased with the amplitudes of the activating, or preceding inactivating, steps. Maximum values of peak Na+ current were independently influenced by genotype but not age or interacting effects of genotype and age on two-way ANOVA. Neither genotype, nor age, whether independently or interactively, influenced voltages at half-maximal current, or steepness factors, for current activation and inactivation, or time constants for recovery from inactivation following repolarisation. In contrast, delayed outward (K+) currents showed similar activation and rectification properties through all experimental groups. These findings directly demonstrate and implicate reduced Na+ in contrast to unchanged K+ current, as a mechanism for slowed conduction causing atrial arrhythmogenicity in Pgc-1β−/− hearts.
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Affiliation(s)
- Haseeb Valli
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom
| | - Shiraz Ahmad
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom
| | - Anita Y Jiang
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom
| | - Robert Smyth
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom
| | - Kamalan Jeevaratnam
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom; Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7AL, Surrey, United Kingdom; PU-RCSI School of Medicine, Perdana University, 43400 Serdang, Selangor Darul Ehsan, Malaysia
| | - Hugh R Matthews
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, United Kingdom; Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, United Kingdom.
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26
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Derangeon M, Montnach J, Cerpa CO, Jagu B, Patin J, Toumaniantz G, Girardeau A, Huang CLH, Colledge WH, Grace AA, Baró I, Charpentier F. Transforming growth factor β receptor inhibition prevents ventricular fibrosis in a mouse model of progressive cardiac conduction disease. Cardiovasc Res 2017; 113:464-474. [PMID: 28339646 DOI: 10.1093/cvr/cvx026] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 02/16/2017] [Indexed: 01/12/2023] Open
Abstract
Aims Loss-of-function mutations in SCN5A, the gene encoding NaV1.5 channel, have been associated with inherited progressive cardiac conduction disease (PCCD). We have proposed that Scn5a heterozygous knock-out (Scn5a+/-) mice, which are characterized by ventricular fibrotic remodelling with ageing, represent a model for PCCD. Our objectives were to identify the molecular pathway involved in fibrosis development and prevent its activation. Methods and results Our study shows that myocardial interstitial fibrosis occurred in Scn5a+/- mice only after 45 weeks of age. Fibrosis was triggered by transforming growth factor β (TGF-β) pathway activation. Younger Scn5a+/- mice were characterized by a higher connexin 43 expression than wild-type (WT) mice. After the age of 45 weeks, connexin 43 expression decreased in both WT and Scn5a+/- mice, although the decrease was larger in Scn5a+/- mice. Chronic inhibition of cardiac sodium current with flecainide (50 mg/kg/day p.o) in WT mice from the age of 6 weeks to the age of 60 weeks did not lead to TGF-β pathway activation and fibrosis. Chronic inhibition of TGF-β receptors with GW788388 (5 mg/kg/day p.o.) in Scn5a+/- mice from the age of 45 weeks to the age of 60 weeks prevented the occurrence of fibrosis. However, current data could not detect reduction in QRS duration with GW788388. Conclusion Myocardial fibrosis secondary to a loss of NaV1.5 is triggered by TGF-β signalling pathway. Those events are more likely secondary to the decreased NaV1.5 sarcolemmal expression rather than the decreased Na+ current per se. TGF-β receptor inhibition prevents age-dependent development of ventricular fibrosis in Scn5a+/- mouse.
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Affiliation(s)
- Mickael Derangeon
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Jérôme Montnach
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Cynthia Ore Cerpa
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Benoit Jagu
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Justine Patin
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Gilles Toumaniantz
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Aurore Girardeau
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Christopher L H Huang
- The Section of Cardiovascular Biology, Departments of Biochemistry and Physiology, University of Cambridge, Downing street, Cambridge CB23EG, UK
| | - William H Colledge
- The Section of Cardiovascular Biology, Departments of Biochemistry and Physiology, University of Cambridge, Downing street, Cambridge CB23EG, UK
| | - Andrew A Grace
- The Section of Cardiovascular Biology, Departments of Biochemistry and Physiology, University of Cambridge, Downing street, Cambridge CB23EG, UK
| | - Isabelle Baró
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France
| | - Flavien Charpentier
- INSERM, UMR1087, l'institut du thorax, quai Moncousu, Nantes F-44000, France.,CNRS, UMR6291, quai Moncousu, Nantes F-44000, France.,Université de Nantes, quai Moncousu, Nantes F-44000, France.,CHU Nantes, Alexis Ricordeau, Nantes F-44000, France
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27
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Ton AT, Biet M, Delabre JF, Morin N, Dumaine R. In-utero exposure to nicotine alters the development of the rabbit cardiac conduction system and provides a potential mechanism for sudden infant death syndrome. Arch Toxicol 2017; 91:3947-3960. [PMID: 28593499 DOI: 10.1007/s00204-017-2006-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 06/01/2017] [Indexed: 01/06/2023]
Abstract
In-utero exposure to tobacco smoke remains the highest risk factor for sudden infant death syndrome (SIDS). To alleviate the risks, nicotine replacement therapies are often prescribed to women who wish to quit smoking during their pregnancy. Cardiac arrhythmias is considered the final outcome leading to sudden death. Our goal in this study was to determine if exposing rabbit fetus to nicotine altered the cardiac conduction system of newborn kittens in a manner susceptible to cause SIDS. Using neuronal markers and a series of immunohistological and electrophysiological techniques we found that nicotine delayed the development of the cardiac pacemaker center (sinoatrial node) and decreased its innervation. At the molecular level, nicotine favored the expression of cardiac sodium channels with biophysical properties that will tend to slow heart rate and diminish electrical conduction. Our results show that alterations of the cardiac sodium current may contribute to the bradycardia, conduction disturbances and other cardiac arrhythmias often associated to SIDS and raise awareness on the use of replacement therapy during pregnancy.
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Affiliation(s)
- Anh Tuan Ton
- Department of Pharmacology and Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001 12th ave, Sherbrooke, QC, Canada
- Montreal Heart Institute, University of Montreal, Montréal, QC, Canada
| | - Michael Biet
- Department of Pharmacology and Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001 12th ave, Sherbrooke, QC, Canada
| | - Jean-Francois Delabre
- Department of Pharmacology and Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001 12th ave, Sherbrooke, QC, Canada
| | - Nathalie Morin
- Department of Pharmacology and Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001 12th ave, Sherbrooke, QC, Canada
| | - Robert Dumaine
- Department of Pharmacology and Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001 12th ave, Sherbrooke, QC, Canada.
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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.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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29
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Development of the cardiac pacemaker. Cell Mol Life Sci 2016; 74:1247-1259. [PMID: 27770149 DOI: 10.1007/s00018-016-2400-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 10/16/2016] [Accepted: 10/17/2016] [Indexed: 01/11/2023]
Abstract
The sinoatrial node (SAN) is the dominant pacemaker of the heart. Abnormalities in SAN formation and function can cause sinus arrhythmia, including sick sinus syndrome and sudden death. A better understanding of genes and signaling pathways that regulate SAN development and function is essential to develop more effective treatment to sinus arrhythmia, including biological pacemakers. In this review, we briefly summarize the key processes of SAN morphogenesis during development, and focus on the transcriptional network that drives SAN development.
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Liu M, Yang KC, Dudley SC. Cardiac Sodium Channel Mutations: Why so Many Phenotypes? CURRENT TOPICS IN MEMBRANES 2016; 78:513-59. [PMID: 27586294 DOI: 10.1016/bs.ctm.2015.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The cardiac Na(+) channel (Nav1.5) conducts a depolarizing inward Na(+) current that is responsible for the generation of the upstroke Phase 0 of the action potential. In heart tissue, changes in Na(+) currents can affect conduction velocity and impulse propagation. The cardiac Nav1.5 is also involved in determination of the action potential duration, since some channels may reopen during the plateau phase, generating a persistent or late inward current. Mutations of cardiac Nav1.5 can induce gain or loss of channel function because of an increased late current or a decrease of peak current, respectively. Gain-of-function mutations cause Long QT syndrome type 3 and possibly atrial fibrillation, while loss-of-function channel mutations are associated with a wider variety of phenotypes, such as Brugada syndrome, cardiac conduction disease, dilated cardiomyopathy, and sick sinus node syndrome. The penetrance and phenotypes resulting from Nav1.5 mutations also vary with age, gender, body temperature, circadian rhythm, and between regions of the heart. This phenotypic variability makes it difficult to correlate genotype-phenotype. We propose that mutations are only one contributor to the phenotype and additional modifications on Nav1.5 lead to the phenotypic variability. Possible modifiers include other genetic variations and alterations in the life cycle of Nav1.5 such as gene transcription, RNA processing, translation, posttranslational modifications, trafficking, complex assembly, and degradation. In this chapter, we summarize potential modifiers of cardiac Nav1.5 that could help explain the clinically observed phenotypic variability. Consideration of these modifiers could help improve genotype-phenotype correlations and lead to new therapeutic strategies.
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Affiliation(s)
- M Liu
- The Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - K-C Yang
- The Warren Alpert Medical School of Brown University, Providence, RI, United States
| | - S C Dudley
- The Warren Alpert Medical School of Brown University, Providence, RI, United States
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Liu J, Laksman Z, Backx PH. The electrophysiological development of cardiomyocytes. Adv Drug Deliv Rev 2016; 96:253-73. [PMID: 26788696 DOI: 10.1016/j.addr.2015.12.023] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 12/23/2015] [Accepted: 12/31/2015] [Indexed: 02/07/2023]
Abstract
The generation of human cardiomyocytes (CMs) from human pluripotent stem cells (hPSCs) has become an important resource for modeling human cardiac disease and for drug screening, and also holds significant potential for cardiac regeneration. Many challenges remain to be overcome however, before innovation in this field can translate into a change in the morbidity and mortality associated with heart disease. Of particular importance for the future application of this technology is an improved understanding of the electrophysiologic characteristics of CMs, so that better protocols can be developed and optimized for generating hPSC-CMs. Many different cell culture protocols are currently utilized to generate CMs from hPSCs and all appear to yield relatively “developmentally” immature CMs with highly heterogeneous electrical properties. These hPSC-CMs are characterized by spontaneous beating at highly variable rates with a broad range of depolarization-repolarization patterns, suggestive of mixed populations containing atrial, ventricular and nodal cells. Many recent studies have attempted to introduce approaches to promote maturation and to create cells with specific functional properties. In this review, we summarize the studies in which the electrical properties of CMs derived from stem cells have been examined. In order to place this information in a useful context, we also review the electrical properties of CMs as they transition from the developing embryo to the adult human heart. The signal pathways involved in the regulation of ion channel expression during development are also briefly considered.
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Choisy SC, Cheng H, Orchard CH, James AF, Hancox JC. Electrophysiological properties of myocytes isolated from the mouse atrioventricular node: L-type ICa, IKr, If, and Na-Ca exchange. Physiol Rep 2015; 3:3/11/e12633. [PMID: 26607172 PMCID: PMC4673654 DOI: 10.14814/phy2.12633] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The atrioventricular node (AVN) is a key component of the cardiac pacemaker-conduction system. This study investigated the electrophysiology of cells isolated from the AVN region of adult mouse hearts, and compared murine ionic current magnitude with that of cells from the more extensively studied rabbit AVN. Whole-cell patch-clamp recordings of ionic currents, and perforated-patch recordings of action potentials (APs), were made at 35-37°C. Hyperpolarizing voltage commands from -40 mV elicited a Ba(2+)-sensitive inward rectifier current that was small at diastolic potentials. Some cells (Type 1; 33.4 ± 2.2 pF; n = 19) lacked the pacemaker current, If, whilst others (Type 2; 34.2 ± 1.5 pF; n = 21) exhibited a clear If, which was larger than in rabbit AVN cells. On depolarization from -40 mV L-type Ca(2+) current, IC a,L, was elicited with a half maximal activation voltage (V0.5) of -7.6 ± 1.2 mV (n = 24). IC a,L density was smaller than in rabbit AVN cells. Rapid delayed rectifier (IK r) tail currents sensitive to E-4031 (5 μmol/L) were observed on repolarization to -40 mV, with an activation V0.5 of -10.7 ± 4.7 mV (n = 8). The IK r magnitude was similar in mouse and rabbit AVN. Under Na-Ca exchange selective conditions, mouse AVN cells exhibited 5 mmol/L Ni-sensitive exchange current that was inwardly directed negative to the holding potential (-40 mV). Spontaneous APs (5.2 ± 0.5 sec(-1); n = 6) exhibited an upstroke velocity of 37.7 ± 16.2 V/s and ceased following inhibition of sarcoplasmic reticulum Ca(2+) release by 1 μmol/L ryanodine, implicating intracellular Ca(2+) cycling in murine AVN cell electrogenesis.
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Affiliation(s)
- Stéphanie C Choisy
- School of Physiology and Pharmacology and Cardiovascular Research Laboratories, Biomedical Sciences Building, University of Bristol, Bristol, United Kingdom
| | - Hongwei Cheng
- School of Physiology and Pharmacology and Cardiovascular Research Laboratories, Biomedical Sciences Building, University of Bristol, Bristol, United Kingdom
| | - Clive H Orchard
- School of Physiology and Pharmacology and Cardiovascular Research Laboratories, Biomedical Sciences Building, University of Bristol, Bristol, United Kingdom
| | - Andrew F James
- School of Physiology and Pharmacology and Cardiovascular Research Laboratories, Biomedical Sciences Building, University of Bristol, Bristol, United Kingdom
| | - Jules C Hancox
- School of Physiology and Pharmacology and Cardiovascular Research Laboratories, Biomedical Sciences Building, University of Bristol, Bristol, United Kingdom
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Age-dependent alterations of voltage-gated Na(+) channel isoforms in rat sinoatrial node. Mech Ageing Dev 2015; 152:80-90. [PMID: 26528804 DOI: 10.1016/j.mad.2015.10.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Revised: 10/08/2015] [Accepted: 10/26/2015] [Indexed: 02/06/2023]
Abstract
Multiple isoforms of voltage-gated Na(+) channels (NaChs) have been identified in sinoatrial node (SAN) and contribute to a rapid intrinsic heart rate. However, their roles in aging remain unclear. Here, we sought to clarify whether the age-related expression of NaChs contributes to the impaired SAN function during aging. Blockade of the tetrodotoxin (TTX)-sensitive Na(+) current with nanomolar concentrations of TTX prolonged the cycle length (CL) in both the rat intact heart and SAN. The effect of nanomolar concentrations of TTX on SAN pacemaking was lessened in adulthood compared with that in youth. Interestingly, the pacemaking became more sensitive to TTX and TTX-induced sinus arrhythmias occurred more frequently in the senescent group. The presences of NaCh α subunit isoforms Nav1.1, Nav1.6 as well as β subunit isoforms Navβ1 and Navβ3 in SAN were confirmed by immunohistochemistry. Western blot revealed a declination of Nav1.1, Nav1.6, Navβ1 and Navβ3 proteins during aging. Furthermore, laser captured SAN cells were used for further real-time quantitative RT-PCR analysis, which also confirmed the presences of Nav1.1, Nav1.6, Navβ1 and Navβ3 mRNA and their reduced levels in rat SAN during aging. These results indicated an age-dependent alterations in expression and relative function of NaCh in rat SAN.
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Kim GE, Ross JL, Xie C, Su KN, Zaha VG, Wu X, Palmeri M, Ashraf M, Akar JG, Russell KS, Akar FG, Young LH. LKB1 deletion causes early changes in atrial channel expression and electrophysiology prior to atrial fibrillation. Cardiovasc Res 2015; 108:197-208. [PMID: 26378152 PMCID: PMC4571838 DOI: 10.1093/cvr/cvv212] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 07/09/2015] [Accepted: 07/14/2015] [Indexed: 12/19/2022] Open
Abstract
AIMS Liver kinase B1 (LKB1) is a protein kinase that activates the metabolic regulator AMP-activated protein kinase (AMPK) and other related kinases. Deletion of LKB1 in mice leads to cardiomyopathy and atrial fibrillation (AF). However, the specific role of the LKB1 pathway in early atrial biology remains unknown. Thus, we investigated whether LKB1 deletion altered atrial channel expression and electrophysiological function in a cardiomyocyte-specific knockout mouse model. METHODS AND RESULTS We performed a systematic comparison of αMHC-Cre LKB1(fl/fl) and littermate LKB1(fl/fl) male mice. This included analysis of gene expression, histology, and echocardiography, as well as cellular and tissue-level electrophysiology using patch-clamp recordings in vitro, optical mapping ex vivo, and ECG recordings in vivo. At postnatal day 1, atrial depolarization was prolonged, and Nav1.5 and Cx40 expression were markedly down-regulated in MHC-Cre LKB1(fl/fl) mice. Inward sodium current density was significantly decreased in MHC-Cre LKB1(fl/fl) neonatal atrial myocytes. Subsequently, additional alterations in atrial channel expression, atrial fibrosis, and spontaneous onset of AF developed by 2 weeks of age. In adult mice, abnormalities of interatrial conduction and bi-atrial electrical coupling were observed, likely promoting the perpetuation of AF. Mice with AMPK-inactivated hearts demonstrated modest overlap in channel expression with MHC-Cre LKB1(fl/fl) hearts, but retained normal structure, electrophysiological function and contractility. CONCLUSIONS Deletion of LKB1 causes early defects in atrial channel expression, action potential generation and conduction, which precede widespread atrial remodelling, fibrosis and AF. LKB1 is critical for normal atrial growth and electrophysiological function.
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Affiliation(s)
- Grace E Kim
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT 06520, USA
| | - Jenna L Ross
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Chaoqin Xie
- Cardiovascular Research Center, Mt. Sinai School of Medicine, New York, NY 10029, USA
| | - Kevin N Su
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT 06520, USA
| | - Vlad G Zaha
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Xiaohong Wu
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Monica Palmeri
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Mohammed Ashraf
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Joseph G Akar
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Kerry S Russell
- Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Fadi G Akar
- Cardiovascular Research Center, Mt. Sinai School of Medicine, New York, NY 10029, USA
| | - Lawrence H Young
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT 06520, USA Yale Cardiovascular Research Center, Section of Cardiovascular Medicine, Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
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Veerman CC, Wilde AAM, Lodder EM. The cardiac sodium channel gene SCN5A and its gene product NaV1.5: Role in physiology and pathophysiology. Gene 2015; 573:177-87. [PMID: 26361848 DOI: 10.1016/j.gene.2015.08.062] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Revised: 07/31/2015] [Accepted: 08/27/2015] [Indexed: 12/18/2022]
Abstract
The gene SCN5A encodes the main cardiac sodium channel NaV1.5. This channel predominates the cardiac sodium current, INa, which underlies the fast upstroke of the cardiac action potential. As such, it plays a crucial role in cardiac electrophysiology. Over the last 60years a tremendous amount of knowledge regarding its function at the electrophysiological and molecular level has been acquired. Furthermore, genetic studies have shown that mutations in SCN5A are associated with multiple cardiac diseases (e.g. Brugada syndrome, Long QT syndrome, conduction disease and cardiomyopathy), while genetic variation in the general population has been associated with differences in cardiac conduction and risk of arrhythmia through genome wide association studies. In this review we aim to give an overview of the current knowledge (and the gaps therein) on SCN5A and NaV1.5.
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Affiliation(s)
- Christiaan C Veerman
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands
| | - Arthur A M Wilde
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands.
| | - Elisabeth M Lodder
- Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands.
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Monfredi O, Boyett MR. Sick sinus syndrome and atrial fibrillation in older persons - A view from the sinoatrial nodal myocyte. J Mol Cell Cardiol 2015; 83:88-100. [PMID: 25668431 DOI: 10.1016/j.yjmcc.2015.02.003] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 01/30/2015] [Accepted: 02/02/2015] [Indexed: 01/02/2023]
Abstract
Sick sinus syndrome remains a highly relevant clinical entity, being responsible for the implantation of the majority of electronic pacemakers worldwide. It is an infinitely more complex disease than it was believed when first described in the mid part of the 20th century. It not only involves the innate leading pacemaker region of the heart, the sinoatrial node, but also the atrial myocardium, predisposing to atrial tachydysrhythmias. It remains controversial as to whether the dysfunction of the sinoatrial node directly causes the dysfunction of the atrial myocardium, or vice versa, or indeed whether these two aspects of the condition arise through some related underlying pathological mechanism, such as extracellular matrix remodeling, i.e., fibrosis. This review aims to shed new light on the myriad possible contributing factors in the development of sick sinus syndrome, with a particular focus on the sinoatrial nodal myocyte. This article is part of a Special Issue entitled CV Aging.
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Affiliation(s)
- O Monfredi
- Institute of Cardiovascular Sciences, University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK.
| | - M R Boyett
- Institute of Cardiovascular Sciences, University of Manchester, 46 Grafton Street, Manchester M13 9NT, UK
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Makara MA, Curran J, Little SC, Musa H, Polina I, Smith SA, Wright PJ, Unudurthi SD, Snyder J, Bennett V, Hund TJ, Mohler PJ. Ankyrin-G coordinates intercalated disc signaling platform to regulate cardiac excitability in vivo. Circ Res 2014; 115:929-38. [PMID: 25239140 DOI: 10.1161/circresaha.115.305154] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
RATIONALE Nav1.5 (SCN5A) is the primary cardiac voltage-gated Nav channel. Nav1.5 is critical for cardiac excitability and conduction, and human SCN5A mutations cause sinus node dysfunction, atrial fibrillation, conductional abnormalities, and ventricular arrhythmias. Further, defects in Nav1.5 regulation are linked with malignant arrhythmias associated with human heart failure. Consequently, therapies to target select Nav1.5 properties have remained at the forefront of cardiovascular medicine. However, despite years of investigation, the fundamental pathways governing Nav1.5 membrane targeting, assembly, and regulation are still largely undefined. OBJECTIVE Define the in vivo mechanisms underlying Nav1.5 membrane regulation. METHODS AND RESULTS Here, we define the molecular basis of an Nav channel regulatory platform in heart. Using new cardiac-selective ankyrin-G(-/-) mice (conditional knock-out mouse), we report that ankyrin-G targets Nav1.5 and its regulatory protein calcium/calmodulin-dependent kinase II to the intercalated disc. Mechanistically, βIV-spectrin is requisite for ankyrin-dependent targeting of calcium/calmodulin-dependent kinase II-δ; however, βIV-spectrin is not essential for ankyrin-G expression. Ankyrin-G conditional knock-out mouse myocytes display decreased Nav1.5 expression/membrane localization and reduced INa associated with pronounced bradycardia, conduction abnormalities, and ventricular arrhythmia in response to Nav channel antagonists. Moreover, we report that ankyrin-G links Nav channels with broader intercalated disc signaling/structural nodes, as ankyrin-G loss results in reorganization of plakophilin-2 and lethal arrhythmias in response to β-adrenergic stimulation. CONCLUSIONS Our findings provide the first in vivo data for the molecular pathway required for intercalated disc Nav1.5 targeting/regulation in heart. Further, these new data identify the basis of an in vivo cellular platform critical for membrane recruitment and regulation of Nav1.5.
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Affiliation(s)
- Michael A Makara
- From The Dorothy M. Davis Heart & Lung Research Institute (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., S.D.U., J.S., T.J.H., P.J.M. ), Departments of Internal Medicine (S.A.S., P.J.M.), and Physiology and Cell Biology (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus; Department of Biomedical Engineering, The Ohio State University College of Engineering, Columbus (S.D.U., J.S., T.J.H.); and Howard Hughes Medical Institute, Department of Biochemistry, Duke University Medical Center, Durham, NC (V.B.)
| | - Jerry Curran
- From The Dorothy M. Davis Heart & Lung Research Institute (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., S.D.U., J.S., T.J.H., P.J.M. ), Departments of Internal Medicine (S.A.S., P.J.M.), and Physiology and Cell Biology (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus; Department of Biomedical Engineering, The Ohio State University College of Engineering, Columbus (S.D.U., J.S., T.J.H.); and Howard Hughes Medical Institute, Department of Biochemistry, Duke University Medical Center, Durham, NC (V.B.)
| | - Sean C Little
- From The Dorothy M. Davis Heart & Lung Research Institute (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., S.D.U., J.S., T.J.H., P.J.M. ), Departments of Internal Medicine (S.A.S., P.J.M.), and Physiology and Cell Biology (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus; Department of Biomedical Engineering, The Ohio State University College of Engineering, Columbus (S.D.U., J.S., T.J.H.); and Howard Hughes Medical Institute, Department of Biochemistry, Duke University Medical Center, Durham, NC (V.B.)
| | - Hassan Musa
- From The Dorothy M. Davis Heart & Lung Research Institute (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., S.D.U., J.S., T.J.H., P.J.M. ), Departments of Internal Medicine (S.A.S., P.J.M.), and Physiology and Cell Biology (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus; Department of Biomedical Engineering, The Ohio State University College of Engineering, Columbus (S.D.U., J.S., T.J.H.); and Howard Hughes Medical Institute, Department of Biochemistry, Duke University Medical Center, Durham, NC (V.B.)
| | - Iuliia Polina
- From The Dorothy M. Davis Heart & Lung Research Institute (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., S.D.U., J.S., T.J.H., P.J.M. ), Departments of Internal Medicine (S.A.S., P.J.M.), and Physiology and Cell Biology (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus; Department of Biomedical Engineering, The Ohio State University College of Engineering, Columbus (S.D.U., J.S., T.J.H.); and Howard Hughes Medical Institute, Department of Biochemistry, Duke University Medical Center, Durham, NC (V.B.)
| | - Sakima A Smith
- From The Dorothy M. Davis Heart & Lung Research Institute (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., S.D.U., J.S., T.J.H., P.J.M. ), Departments of Internal Medicine (S.A.S., P.J.M.), and Physiology and Cell Biology (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus; Department of Biomedical Engineering, The Ohio State University College of Engineering, Columbus (S.D.U., J.S., T.J.H.); and Howard Hughes Medical Institute, Department of Biochemistry, Duke University Medical Center, Durham, NC (V.B.)
| | - Patrick J Wright
- From The Dorothy M. Davis Heart & Lung Research Institute (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., S.D.U., J.S., T.J.H., P.J.M. ), Departments of Internal Medicine (S.A.S., P.J.M.), and Physiology and Cell Biology (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus; Department of Biomedical Engineering, The Ohio State University College of Engineering, Columbus (S.D.U., J.S., T.J.H.); and Howard Hughes Medical Institute, Department of Biochemistry, Duke University Medical Center, Durham, NC (V.B.)
| | - Sathya D Unudurthi
- From The Dorothy M. Davis Heart & Lung Research Institute (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., S.D.U., J.S., T.J.H., P.J.M. ), Departments of Internal Medicine (S.A.S., P.J.M.), and Physiology and Cell Biology (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus; Department of Biomedical Engineering, The Ohio State University College of Engineering, Columbus (S.D.U., J.S., T.J.H.); and Howard Hughes Medical Institute, Department of Biochemistry, Duke University Medical Center, Durham, NC (V.B.)
| | - Jed Snyder
- From The Dorothy M. Davis Heart & Lung Research Institute (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., S.D.U., J.S., T.J.H., P.J.M. ), Departments of Internal Medicine (S.A.S., P.J.M.), and Physiology and Cell Biology (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus; Department of Biomedical Engineering, The Ohio State University College of Engineering, Columbus (S.D.U., J.S., T.J.H.); and Howard Hughes Medical Institute, Department of Biochemistry, Duke University Medical Center, Durham, NC (V.B.)
| | - Vann Bennett
- From The Dorothy M. Davis Heart & Lung Research Institute (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., S.D.U., J.S., T.J.H., P.J.M. ), Departments of Internal Medicine (S.A.S., P.J.M.), and Physiology and Cell Biology (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus; Department of Biomedical Engineering, The Ohio State University College of Engineering, Columbus (S.D.U., J.S., T.J.H.); and Howard Hughes Medical Institute, Department of Biochemistry, Duke University Medical Center, Durham, NC (V.B.)
| | - Thomas J Hund
- From The Dorothy M. Davis Heart & Lung Research Institute (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., S.D.U., J.S., T.J.H., P.J.M. ), Departments of Internal Medicine (S.A.S., P.J.M.), and Physiology and Cell Biology (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus; Department of Biomedical Engineering, The Ohio State University College of Engineering, Columbus (S.D.U., J.S., T.J.H.); and Howard Hughes Medical Institute, Department of Biochemistry, Duke University Medical Center, Durham, NC (V.B.)
| | - Peter J Mohler
- From The Dorothy M. Davis Heart & Lung Research Institute (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., S.D.U., J.S., T.J.H., P.J.M. ), Departments of Internal Medicine (S.A.S., P.J.M.), and Physiology and Cell Biology (M.A.M., J.C., S.C.L., H.M., I.P., S.A.S., P.J.W., P.J.M.), The Ohio State University Wexner Medical Center, Columbus; Department of Biomedical Engineering, The Ohio State University College of Engineering, Columbus (S.D.U., J.S., T.J.H.); and Howard Hughes Medical Institute, Department of Biochemistry, Duke University Medical Center, Durham, NC (V.B.).
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Zhang Y, Guzadhur L, Jeevaratnam K, Salvage SC, Matthews GDK, Lammers WJ, Lei M, Huang CL, Fraser JA. Arrhythmic substrate, slowed propagation and increased dispersion in conduction direction in the right ventricular outflow tract of murine Scn5a+/- hearts. Acta Physiol (Oxf) 2014; 211:559-73. [PMID: 24913289 PMCID: PMC4296345 DOI: 10.1111/apha.12324] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 05/23/2014] [Accepted: 06/03/2014] [Indexed: 12/18/2022]
Abstract
Aim To test a hypothesis attributing arrhythmia in Brugada Syndrome to right ventricular (RV) outflow tract (RVOT) conduction abnormalities arising from Nav1.5 insufficiency and fibrotic change. Methods Arrhythmic properties of Langendorff-perfused Scn5a+/− and wild-type mouse hearts were correlated with ventricular effective refractory periods (VERPs), multi-electrode array (MEA) measurements of action potential (AP) conduction velocities and dispersions in conduction direction (CD), Nav1.5 expression levels, and fibrotic change, as measured at the RVOT and RV. Two-way anova was used to test for both independent and interacting effects of anatomical region and genotype on these parameters. Results Scn5a+/− hearts showed greater arrhythmic frequencies during programmed electrical stimulation at the RVOT but not the RV. The Scn5a+/− genotype caused an independent increase of VERP regardless of whether the recording site was the RVOT or RV. Effective AP conduction velocities (CV†s), derived from fitting regression planes to arrays of observed local activation times were reduced in Scn5a+/− hearts and at the RVOT independently. AP conduction velocity magnitudes derived by averaging MEA results from local vector analyses, CV*, were reduced by the Scn5a+/− genotype alone. In contrast, dispersions in conduction direction, were greater in the RVOT than the RV, when the atrioventricular node was used as the pacing site. The observed reductions in Nav1.5 expression were attributable to Scn5a+/−, whereas increased levels of fibrosis were associated with the RVOT. Conclusions The Scn5a+/− RVOT recapitulates clinical findings of increased arrhythmogenicity through reduced CV† reflecting reduced CV* attributable to reduced Nav1.5 expression and increased CD attributable to fibrosis.
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Affiliation(s)
- Y. Zhang
- Physiological Laboratory University of Cambridge Cambridge UK
- Heart Centre Northwest Women's and Children's Hospital Xi'an China
| | - L. Guzadhur
- Physiological Laboratory University of Cambridge Cambridge UK
| | - K. Jeevaratnam
- Physiological Laboratory University of Cambridge Cambridge UK
- Perdana University‐Royal College of Surgeons Ireland Selangor Malaysia
| | - S. C. Salvage
- Physiological Laboratory University of Cambridge Cambridge UK
| | | | - W. J. Lammers
- Department of Physiology College of Medicine and Health Sciences Al Ain UAE
| | - M. Lei
- Department of Pharmacology University of Oxford Oxford UK
| | - C. L.‐H. Huang
- Physiological Laboratory University of Cambridge Cambridge UK
- Department of Biochemistry University of Cambridge Cambridge UK
| | - J. A. Fraser
- Physiological Laboratory University of Cambridge Cambridge UK
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Ziyadeh-Isleem A, Clatot J, Duchatelet S, Gandjbakhch E, Denjoy I, Hidden-Lucet F, Hatem S, Deschênes I, Coulombe A, Neyroud N, Guicheney P. A truncating SCN5A mutation combined with genetic variability causes sick sinus syndrome and early atrial fibrillation. Heart Rhythm 2014; 11:1015-1023. [PMID: 24582607 PMCID: PMC4056672 DOI: 10.1016/j.hrthm.2014.02.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Indexed: 01/08/2023]
Abstract
BACKGROUND Mutations in the SCN5A gene, encoding the α subunit of the cardiac Na(+) channel, Nav1.5, can result in several life-threatening arrhythmias. OBJECTIVE To characterize a distal truncating SCN5A mutation, R1860Gfs*12, identified in a family with different phenotypes including sick sinus syndrome, atrial fibrillation (AF), atrial flutter, and atrioventricular block. METHODS Patch-clamp and biochemical analyses were performed in human embryonic kidney 293 cells transfected with wild-type (WT) and/or mutant channels. RESULTS The mutant channel expressed alone caused a 70% reduction in inward sodium current (INa) density compared to WT currents, which was consistent with its partial proteasomal degradation. It also led to a negative shift of steady-state inactivation and to a persistent current. When mimicking the heterozygous state of the patients by coexpressing WT and R1860Gfs*12 channels, the biophysical properties of INa were still altered and the mutant channel α subunits still interacted with the WT channels. Since the proband developed paroxysmal AF at a young age, we screened 17 polymorphisms associated with AF risk in this family and showed that the proband carries at-risk polymorphisms upstream of PITX2, a gene widely associated with AF development. In addition, when mimicking the difference in resting membrane potentials between cardiac atria and ventricles in human embryonic kidney 293 cells or when using computer model simulations, R1860Gfs*12 induced a more drastic decrease in INa at the atrial potential. CONCLUSION We have identified a distal truncated SCN5A mutant associated with gain- and loss-of-function effects, leading to sick sinus syndrome and atrial arrhythmias. A constitutively higher susceptibility to arrhythmias of atrial tissues and genetic variability could explain the complex phenotype observed in this family.
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Affiliation(s)
- Azza Ziyadeh-Isleem
- INSERM, UMR_S1166, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S1166, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France
| | - Jérôme Clatot
- INSERM, UMR_S1166, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S1166, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France
- Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, OH, USA
| | - Sabine Duchatelet
- INSERM, UMR_S1166, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S1166, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France
| | - Estelle Gandjbakhch
- INSERM, UMR_S1166, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S1166, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France
- AP-HP, Hôpital Pitié-Salpêtrière, Département de Cardiologie, Paris, France
| | - Isabelle Denjoy
- INSERM, UMR_S1166, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S1166, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France
- AP-HP, Hôpital Bichat, Département de Cardiologie, Centre de Référence des Maladies Cardiaques Héréditaires, Paris, France
| | - Françoise Hidden-Lucet
- INSERM, UMR_S1166, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S1166, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France
- AP-HP, Hôpital Pitié-Salpêtrière, Département de Cardiologie, Paris, France
| | - Stéphane Hatem
- INSERM, UMR_S1166, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S1166, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France
| | - Isabelle Deschênes
- Heart and Vascular Research Center, MetroHealth Campus, Case Western Reserve University, Cleveland, OH, USA
| | - Alain Coulombe
- INSERM, UMR_S1166, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S1166, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France
| | - Nathalie Neyroud
- INSERM, UMR_S1166, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S1166, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France
| | - Pascale Guicheney
- INSERM, UMR_S1166, Paris, France
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S1166, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France
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Dobrzynski H, Anderson RH, Atkinson A, Borbas Z, D'Souza A, Fraser JF, Inada S, Logantha SJRJ, Monfredi O, Morris GM, Moorman AFM, Nikolaidou T, Schneider H, Szuts V, Temple IP, Yanni J, Boyett MR. Structure, function and clinical relevance of the cardiac conduction system, including the atrioventricular ring and outflow tract tissues. Pharmacol Ther 2013; 139:260-88. [PMID: 23612425 DOI: 10.1016/j.pharmthera.2013.04.010] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 03/28/2013] [Indexed: 01/01/2023]
Abstract
It is now over 100years since the discovery of the cardiac conduction system, consisting of three main parts, the sinus node, the atrioventricular node and the His-Purkinje system. The system is vital for the initiation and coordination of the heartbeat. Over the last decade, immense strides have been made in our understanding of the cardiac conduction system and these recent developments are reviewed here. It has been shown that the system has a unique embryological origin, distinct from that of the working myocardium, and is more extensive than originally thought with additional structures: atrioventricular rings, a third node (so called retroaortic node) and pulmonary and aortic sleeves. It has been shown that the expression of ion channels, intracellular Ca(2+)-handling proteins and gap junction channels in the system is specialised (different from that in the ordinary working myocardium), but appropriate to explain the functioning of the system, although there is continued debate concerning the ionic basis of pacemaking. We are beginning to understand the mechanisms (fibrosis and remodelling of ion channels and related proteins) responsible for dysfunction of the system (bradycardia, heart block and bundle branch block) associated with atrial fibrillation and heart failure and even athletic training. Equally, we are beginning to appreciate how naturally occurring mutations in ion channels cause congenital cardiac conduction system dysfunction. Finally, current therapies, the status of a new therapeutic strategy (use of a specific heart rate lowering drug) and a potential new therapeutic strategy (biopacemaking) are reviewed.
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Campos FO, Davenport MH, dos Santos RW, Nygren A, Giles WR. High heart rate in pregnancy is modulated by augmented expression of an ion channel, HCN-2, in pacemaker tissue. Circulation 2013; 127:2003-5. [PMID: 23609808 DOI: 10.1161/circulationaha.113.002760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Sinus node disease in subjects with type 1 ECG pattern of Brugada syndrome. J Cardiol 2013; 61:227-31. [PMID: 23403368 DOI: 10.1016/j.jjcc.2012.12.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 11/22/2012] [Accepted: 12/04/2012] [Indexed: 11/23/2022]
Abstract
BACKGROUND The spectrum of phenotypes related to mutations of the SCN5A gene include Brugada syndrome (BS), long QT syndrome, progressive cardiac conduction defect, and sinus node disease (SND). The present study investigated the incidence of SND in subjects with type 1 electrocardiogram (ECG) pattern of BS. METHODS AND RESULTS The study population consisted of 68 individuals (55 males, mean age 44.8±12.8 years) with spontaneous (n=27) or drug-induced (n=41) type 1 ECG pattern of BS. Twenty-eight subjects were symptomatic with a history of syncope (41.2%). SND was observed in 6 symptomatic subjects (8.8%), and was mainly attributed to sino-atrial block with sinus pauses. Two patients were initially diagnosed with SND, and received a pacemaker. Patients with SND displayed an increased P-wave duration in leads II and V2, PR interval in leads II and V2, QRS duration in leads II and V2, and increased QTc interval in lead V2 (p<0.05). AH and HV intervals as well as corrected sinus node recovery time (cSNRT) were significantly prolonged in subjects with SND (p<0.05). During a mean follow-up period of 5.0±3.6 years, five subjects with a history of syncope suffered appropriate implantable cardioverter defibrillator (ICD) discharges due to ventricular arrhythmias (7.4%). None of those diagnosed with SND suffered syncope or ICD therapies. CONCLUSION SND is not an uncommon finding in subjects with type 1 ECG pattern of BS. The occurrence of SND in relatively young patients may deserve meticulous investigation including sodium channel blocking test.
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Wu AZY, Loh SH, Cheng TH, Lu HH, Lin CI. Antiarrhythmic effects of (-)-epicatechin-3-gallate, a novel sodium channel agonist in cultured neonatal rat ventricular myocytes. Biochem Pharmacol 2012; 85:69-80. [PMID: 23116965 DOI: 10.1016/j.bcp.2012.10.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 09/24/2012] [Accepted: 10/01/2012] [Indexed: 02/08/2023]
Abstract
(-)-Epicatechin-3-gallate (ECG), a polyphenol extracted from green tea, has been proposed as an effective compound for improving cardiac contractility. However, the therapeutic potential of ECG on the treatment of arrhythmia remains unknown. We investigated the direct actions of ECG on the modulation of ion currents and cardiac cell excitability in the primary culture of neonatal rat ventricular myocyte (NRVM), which is considered a hypertrophic model for analysis of myocardial arrhythmias. By using the whole-cell patch-clamp configurations, we found ECG enhanced the slowly inactivating component of voltage-gated Na(+) currents (I(Na)) in a concentration-dependent manner (0.1-100 μM) with an EC(50) value of 3.8 μM. ECG not only shifted the current-voltage relationship of peak I(Na) to the hyperpolarizing direction but also accelerated I(Na) recovery kinetics. Working at a concentration level of I(Na) enhancement, ECG has no notable effect on voltage-gated K(+) currents and L-type Ca(2+) currents. With culture time increment, the firing rate of spontaneous action potential (sAP) in NRVMs was gradually decreased until spontaneous early after-depolarization (EAD) was observed after about one week culture. ECG increased the firing rate of normal sAP about two-fold without waveform alteration. Interestingly, the bradycardia-dependent EAD could be significantly restored by ECG in fast firing rate to normal sAP waveform. The expression of dominant cardiac sodium channel subunit, Nav1.5, was consistently detected throughout the culture periods. Our results reveal how ECG, the novel I(Na) agonist, may act as a promising candidate in clinical applications on cardiac arrhythmias.
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Affiliation(s)
- Adonis Zhi-Yang Wu
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan, ROC
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Kaese S, Verheule S. Cardiac electrophysiology in mice: a matter of size. Front Physiol 2012; 3:345. [PMID: 22973235 PMCID: PMC3433738 DOI: 10.3389/fphys.2012.00345] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 08/09/2012] [Indexed: 12/27/2022] Open
Abstract
Over the last decade, mouse models have become a popular instrument for studying cardiac arrhythmias. This review assesses in which respects a mouse heart is a miniature human heart, a suitable model for studying mechanisms of cardiac arrhythmias in humans and in which respects human and murine hearts differ. Section I considers the issue of scaling of mammalian cardiac (electro) physiology to body mass. Then, we summarize differences between mice and humans in cardiac activation (section II) and the currents underlying the action potential in the murine working myocardium (section III). Changes in cardiac electrophysiology in mouse models of heart disease are briefly outlined in section IV, while section V discusses technical considerations pertaining to recording cardiac electrical activity in mice. Finally, section VI offers general considerations on the influence of cardiac size on the mechanisms of tachy-arrhythmias.
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Affiliation(s)
- Sven Kaese
- Division of Experimental and Clinical Electrophysiology, Department of Cardiology and Angiology, University Hospital Münster Münster, Germany
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45
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Huang CLH. Andrew Fielding Huxley (1917-2012). J Physiol 2012; 590:3415-20. [PMID: 22855053 PMCID: PMC3547259 DOI: 10.1113/jphysiol.2012.238923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2024] Open
Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge CB2 3EG, UK.
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Huang CLH, Lei L, Matthews GDK, Zhang Y, Lei M. Pathophysiological Mechanisms of Sino-Atrial Dysfunction and Ventricular Conduction Disease Associated with SCN5A Deficiency: Insights from Mouse Models. Front Physiol 2012; 3:234. [PMID: 22783200 PMCID: PMC3390692 DOI: 10.3389/fphys.2012.00234] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 06/11/2012] [Indexed: 11/13/2022] Open
Abstract
Genetically modified mice provide a number of models for studying cardiac channelopathies related to cardiac Na+ channel (SCN5A) abnormalities. We review key pathophysiological features in these murine models that may underlie clinical features observed in sinus node dysfunction and progressive cardiac conduction disease, thereby providing insights into their pathophysiological mechanisms. We describe loss of Na+ channel function and fibrotic changes associated with both loss and gain-of-function Na+ channel mutations. Recent reports further relate the progressive fibrotic changes to upregulation of TGF-β1 production and the transcription factors, Atf3, a stress-inducible gene, and Egr1, to the presence of heterozygous Scn5a gene deletion. Both changes are thus directly implicated in the clinically observed disruptions in sino-atrial node pacemaker function, and sino-atrial and ventricular conduction, and their progression with age. Murine systems with genetic modifications in Scn5a thus prove a useful tool to address questions concerning roles of genetic and environmental modifiers on human SCN5A disease phenotypes.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory, Department of Biochemistry, University of Cambridge Cambridge, UK
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Derangeon M, Montnach J, Baró I, Charpentier F. Mouse Models of SCN5A-Related Cardiac Arrhythmias. Front Physiol 2012; 3:210. [PMID: 22737129 PMCID: PMC3381239 DOI: 10.3389/fphys.2012.00210] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 05/29/2012] [Indexed: 12/19/2022] Open
Abstract
Mutations of SCN5A gene, which encodes the α-subunit of the voltage-gated Na+ channel NaV1.5, underlie hereditary cardiac arrhythmic syndromes such as the type 3 long QT syndrome, cardiac conduction diseases, the Brugada syndrome, the sick sinus syndrome, a trial standstill, and numerous overlap syndromes. Patch-clamp studies in heterologous expression systems have provided important information to understand the genotype-phenotype relationships of these diseases. However, they could not clarify how SCN5A mutations can be responsible for such a large spectrum of diseases, for the late age of onset or the progressiveness of some of these diseases and for the overlapping syndromes. Genetically modified mice rapidly appeared as promising tools for understanding the pathophysiological mechanisms of cardiac SCN5A-related arrhythmic syndromes and several mouse models have been established. This review presents the results obtained on these models that, for most of them, recapitulate the clinical phenotypes of the patients. This includes two models knocked out for Nav1.5 β1 and β3 auxiliary subunits that are also discussed. Despite their own limitations that we point out, the mouse models still appear as powerful tools to elucidate the pathophysiological mechanisms of SCN5A-related diseases and offer the opportunity to investigate the secondary cellular consequences of SCN5A mutations such as the expression remodeling of other genes. This points out the potential role of these genes in the overall human phenotype. Finally, they constitute useful tools for addressing the role of genetic and environmental modifiers on cardiac electrical activity.
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Guzadhur L, Jiang W, Pearcey SM, Jeevaratnam K, Duehmke RM, Grace AA, Lei M, Huang CLH. The Age-dependence of atrial arrhythmogenicity in Scn5a+/−murine hearts reflects alterations in action potential propagation and recovery. Clin Exp Pharmacol Physiol 2012; 39:518-27. [DOI: 10.1111/j.1440-1681.2012.05706.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Laila Guzadhur
- Physiological Laboratory; University of Cambridge; Cambridge; UK
| | - Wenhui Jiang
- Medical College of Xi'an Jiaotong University; Xi'an; China
| | - Sarah M Pearcey
- Physiological Laboratory; University of Cambridge; Cambridge; UK
| | | | - Rudy M Duehmke
- Physiological Laboratory; University of Cambridge; Cambridge; UK
| | - Andrew A Grace
- Department of Biochemistry; University of Cambridge; Cambridge; UK
| | - Ming Lei
- Institute of Cardiovascular Sciences; University of Manchester; Manchester; UK
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Matthews GDK, Guzadhur L, Grace A, Huang CLH. Nonlinearity between action potential alternans and restitution, which both predict ventricular arrhythmic properties in Scn5a+/- and wild-type murine hearts. J Appl Physiol (1985) 2012; 112:1847-63. [PMID: 22461438 DOI: 10.1152/japplphysiol.00039.2012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Electrocardiographic QT- and T-wave alternans, presaging ventricular arrhythmia, reflects compromised adaptation of action potential (AP) duration (APD) to altered heart rate, classically attributed to incomplete Na(v)1.5 channel recovery prior to subsequent stimulation. The restitution hypothesis suggests a function whose slope directly relates to APD alternans magnitude, predicting a critical instability condition, potentially generating arrhythmia. The present experiments directly test for such correlations among arrhythmia, APD alternans and restitution. Mice haploinsufficient in the Scn5a, cardiac Na(+) channel gene (Scn5a(+/-)), previously used to replicate Brugada syndrome, were used, owing to their established arrhythmic properties increased by flecainide and decreased by quinidine, particularly in right ventricular (RV) epicardium. Monophasic APs, obtained during pacing with progressively decrementing cycle lengths, were systematically compared at RV and left ventricular epicardial and endocardial recording sites in Langendorff-perfused Scn5a(+/-) and wild-type hearts before and following flecainide (10 μM) or quinidine (5 μM) application. The extent of alternans was assessed using a novel algorithm. Scn5a(+/-) hearts showed greater frequencies of arrhythmic endpoints with increased incidences of ventricular tachycardia, diminished by quinidine, and earlier onsets of ventricular fibrillation, particularly following flecainide challenge. These features correlated directly with increased refractory periods, specifically in the RV, and abnormal restitution and alternans properties in the RV epicardium. The latter variables were related by a unique, continuous higher-order function, rather than a linear relationship with an unstable threshold. These findings demonstrate a specific relationship between alternans and restitution, as well as confirming their capacity to predict arrhythmia, but implicate mechanisms additional to the voltage feedback suggested in the restitution hypothesis.
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Affiliation(s)
- Gareth D K Matthews
- Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.
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Bakker ML, Boink GJ, Boukens BJ, Verkerk AO, van den Boogaard M, den Haan AD, Hoogaars WM, Buermans HP, de Bakker JM, Seppen J, Tan HL, Moorman AF, 't Hoen PA, Christoffels VM. T-box transcription factor TBX3 reprogrammes mature cardiac myocytes into pacemaker-like cells. Cardiovasc Res 2012; 94:439-49. [DOI: 10.1093/cvr/cvs120] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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