1
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Abrasheva VO, Kovalenko SG, Slotvitsky M, Romanova SА, Aitova AA, Frolova S, Tsvelaya V, Syunyaev RA. Human sodium current voltage-dependence at physiological temperature measured by coupling a patch-clamp experiment to a mathematical model. J Physiol 2024; 602:633-661. [PMID: 38345560 DOI: 10.1113/jp285162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 01/02/2024] [Indexed: 02/20/2024] Open
Abstract
Voltage-gated Na+ channels are crucial to action potential propagation in excitable tissues. Because of the high amplitude and rapid activation of the Na+ current, voltage-clamp measurements are very challenging and are usually performed at room temperature. In this study, we measured Na+ current voltage-dependence in stem cell-derived cardiomyocytes at physiological temperature. While the apparent activation and inactivation curves, measured as the dependence of current amplitude on voltage, fall within the range reported in previous studies, we identified a systematic error in our measurements. This error is caused by the deviation of the membrane potential from the command potential of the amplifier. We demonstrate that it is possible to account for this artifact using computer simulation of the patch-clamp experiment. We obtained surprising results through patch-clamp model optimization: a half-activation of -11.5 mV and a half-inactivation of -87 mV. Although the half-activation deviates from previous research, we demonstrate that this estimate reproduces the conduction velocity dependence on extracellular potassium concentration. KEY POINTS: Voltage-gated Na+ currents play a crucial role in excitable tissues including neurons, cardiac and skeletal muscle. Measurement of Na+ current is challenging because of its high amplitude and rapid kinetics, especially at physiological temperature. We have used the patch-clamp technique to measure human Na+ current voltage-dependence in human induced pluripotent stem cell-derived cardiomyocytes. The patch-clamp data were processed by optimization of the model accounting for voltage-clamp experiment artifacts, revealing a large difference between apparent parameters of Na+ current and the results of the optimization. We conclude that actual Na+ current activation is extremely depolarized in comparison to previous studies. The new Na+ current model provides a better understanding of action potential propagation; we demonstrate that it explains propagation in hyperkalaemic conditions.
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Affiliation(s)
| | - Sandaara G Kovalenko
- Moscow Institute of Physics and Technology, Moscow, Russia
- M. F. Vladimirsky Moscow Regional Research Clinical Institute, Moscow, Russia
- ITMO University, St Petersburg, Russia
| | - Mihail Slotvitsky
- Moscow Institute of Physics and Technology, Moscow, Russia
- M. F. Vladimirsky Moscow Regional Research Clinical Institute, Moscow, Russia
- ITMO University, St Petersburg, Russia
| | - Serafima А Romanova
- Moscow Institute of Physics and Technology, Moscow, Russia
- M. F. Vladimirsky Moscow Regional Research Clinical Institute, Moscow, Russia
| | - Aleria A Aitova
- Moscow Institute of Physics and Technology, Moscow, Russia
- M. F. Vladimirsky Moscow Regional Research Clinical Institute, Moscow, Russia
- ITMO University, St Petersburg, Russia
| | - Sheida Frolova
- Moscow Institute of Physics and Technology, Moscow, Russia
- M. F. Vladimirsky Moscow Regional Research Clinical Institute, Moscow, Russia
| | - Valeria Tsvelaya
- Moscow Institute of Physics and Technology, Moscow, Russia
- M. F. Vladimirsky Moscow Regional Research Clinical Institute, Moscow, Russia
- ITMO University, St Petersburg, Russia
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2
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Banderali U, Moreno M, Martina M. The elusive Na v1.7: From pain to cancer. CURRENT TOPICS IN MEMBRANES 2023; 92:47-69. [PMID: 38007269 DOI: 10.1016/bs.ctm.2023.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2023]
Abstract
Voltage-gated sodium channels (Nav) are protein complexes that play fundamental roles in the transmission of signals in the nervous system, at the neuromuscular junction and in the heart. They are mainly present in excitable cells where they are responsible for triggering action potentials. Dysfunctions in Nav ion conduction give rise to a wide range of conditions, including neurological disorders, hypertension, arrhythmia, pain and cancer. Nav family 1 is composed of nine members, named numerically from 1 to 9. A Nax family also exists and is involved in body-fluid homeostasis. Of particular interest is Nav1.7 which is highly expressed in the sensory neurons of the dorsal root ganglions, where it is involved in the propagation of pain sensation. Gain-of-function mutations in Nav1.7 cause pathologies associated with increased pain sensitivity, while loss-of-function mutations cause reduced sensitivity to pain. The last decade has seen considerable effort in developing highly specific Nav1.7 blockers as pain medications, nonetheless, sufficient efficacy has yet to be achieved. Evidence is now conclusively showing that Navs are also present in many types of cancer cells, where they are involved in cell migration and invasiveness. Nav1.7 is anomalously expressed in endometrial, ovarian and lung cancers. Nav1.7 is also involved in Chemotherapy Induced Peripheral Neuropathy (CIPN). We propose that the knowledge and tools developed to study the role of Nav1.7 in pain can be exploited to develop novel cancer therapies. In this chapter, we illustrate the various aspects of Nav1.7 function in pain, cancer and CIPN, and outline therapeutic approaches.
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Affiliation(s)
- Umberto Banderali
- Human Health Therapeutics Research Centre, National Research Council of Canada, Montreal road, Ottawa, ON, Canada.
| | - Maria Moreno
- Human Health Therapeutics Research Centre, National Research Council of Canada, Montreal road, Ottawa, ON, Canada
| | - Marzia Martina
- Human Health Therapeutics Research Centre, National Research Council of Canada, Montreal road, Ottawa, ON, Canada
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3
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Salvage SC, Jeevaratnam K, Huang CL, Jackson AP. Cardiac sodium channel complexes and arrhythmia: structural and functional roles of the β1 and β3 subunits. J Physiol 2023; 601:923-940. [PMID: 36354758 PMCID: PMC10953345 DOI: 10.1113/jp283085] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 11/04/2022] [Indexed: 11/12/2022] Open
Abstract
In cardiac myocytes, the voltage-gated sodium channel NaV 1.5 opens in response to membrane depolarisation and initiates the action potential. The NaV 1.5 channel is typically associated with regulatory β-subunits that modify gating and trafficking behaviour. These β-subunits contain a single extracellular immunoglobulin (Ig) domain, a single transmembrane α-helix and an intracellular region. Here we focus on the role of the β1 and β3 subunits in regulating NaV 1.5. We catalogue β1 and β3 domain specific mutations that have been associated with inherited cardiac arrhythmia, including Brugada syndrome, long QT syndrome, atrial fibrillation and sudden death. We discuss how new structural insights into these proteins raises new questions about physiological function.
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Affiliation(s)
| | | | - Christopher L.‐H. Huang
- Department of BiochemistryUniversity of CambridgeCambridgeUK
- Department of PhysiologyDevelopment and NeuroscienceUniversity of CambridgeCambridgeUK
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4
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Marchal GA, Remme CA. Subcellular diversity of Nav1.5 in cardiomyocytes: distinct functions, mechanisms and targets. J Physiol 2023; 601:941-960. [PMID: 36469003 DOI: 10.1113/jp283086] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 11/24/2022] [Indexed: 12/11/2022] Open
Abstract
In cardiomyocytes, the rapid depolarisation of the membrane potential is mediated by the α-subunit of the cardiac voltage-gated Na+ channel (NaV 1.5), encoded by the gene SCN5A. This ion channel allows positively charged Na+ ions to enter the cardiomyocyte, resulting in the fast upstroke of the action potential and is therefore crucial for cardiac excitability and electrical propagation. This essential role is underscored by the fact that dysfunctional NaV 1.5 is associated with high risk for arrhythmias and sudden cardiac death. However, development of therapeutic interventions regulating NaV 1.5 has been limited due to the complexity of NaV 1.5 structure and function and its diverse roles within the cardiomyocyte. In particular, research from the last decade has provided us with increased knowledge on the subcellular distribution of NaV 1.5 as well as the proteins which it interacts with in distinct cardiomyocyte microdomains. We here review these insights, detailing the potential role of NaV 1.5 within subcellular domains as well as its dysfunction in the setting of arrhythmia disorders. We furthermore provide an overview of current knowledge on the pathways involved in (microdomain-specific) trafficking of NaV 1.5, and their potential as novel targets. Unravelling the complexity of NaV 1.5 (dys)function may ultimately facilitate the development of therapeutic strategies aimed at preventing lethal arrhythmias. This is not only of importance for pathophysiological conditions where sodium current is specifically decreased within certain subcellular regions, such as in arrhythmogenic cardiomyopathy and Duchenne muscular dystrophy, but also for other acquired and inherited disorders associated with NaV 1.5.
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Affiliation(s)
- Gerard A Marchal
- Department of Experimental Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands.,National Institute of Optics, National Research Council (CNR-INO), Sesto Fiorentino, Florence, Italy
| | - Carol Ann Remme
- Department of Experimental Cardiology, Heart Centre, Amsterdam Cardiovascular Sciences, Heart Failure & Arrhythmias, Amsterdam UMC location University of Amsterdam, Amsterdam, The Netherlands
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5
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Fahy JF, Emerling EW, Sterni LM. Perioperative Management and Considerations for Patients With Voltage-Gated Sodium Channel Mutations: A Pediatric Case Report. A A Pract 2022; 16:e01637. [PMID: 36599048 DOI: 10.1213/xaa.0000000000001637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A 13-year-old girl with a voltage-gated sodium channel mutation (SCN8A)-associated intractable epilepsy presented for bilateral mastectomy for painful juvenile fibroadenomatosis. Sodium channel mutations are more frequently diagnosed with continued advances in genetic testing. Understanding the effects of sodium channel mutations is important to provide safe anesthetic care to these patients. In this article, we discuss what is known regarding the physiology of SCN8A channels and the anesthetic considerations when caring for patients with an SCN8A mutation.
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Affiliation(s)
- John F Fahy
- From the Department of Anesthesiology, Naval Medical Center San Diego, San Diego, California
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6
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Cordenier A, Flamez A, de Ravel T, Gheldof A, Pannone L, De Asmundis C, Pappaert G, Bissay V. Case report: Coexistence of myotonia congenita and Brugada syndrome in one family. Front Neurol 2022; 13:1011956. [PMID: 36212636 PMCID: PMC9537820 DOI: 10.3389/fneur.2022.1011956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 09/05/2022] [Indexed: 11/21/2022] Open
Abstract
Myotonia congenita is a rare neuromuscular disorder caused by CLCN1 mutations resulting in delayed muscle relaxation. Extramuscular manifestations are not considered to be present in chloride skeletal channelopathies, although recently some cardiac manifestations have been described. We report a family with autosomal dominant myotonia congenita and Brugada syndrome. Bearing in mind the previously reported cases of cardiac arrhythmias in myotonia congenita patients, we discuss the possible involvement of the CLCN1-gene mutations in primary cardiac arrhythmia.
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Affiliation(s)
- Ann Cordenier
- Department of Neurology, Center for Neurosciences, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
- *Correspondence: Ann Cordenier
| | - Anja Flamez
- Department of Neurology, Center for Neurosciences, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
| | - Thomy de Ravel
- Center for Medical Genetics, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
| | - Alexander Gheldof
- Center for Medical Genetics, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
| | - Luigi Pannone
- Heart Rhythm Management Centre, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
| | - Carlo De Asmundis
- Heart Rhythm Management Centre, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
| | - Gudrun Pappaert
- Heart Rhythm Management Centre, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
| | - Véronique Bissay
- Department of Neurology, Center for Neurosciences, Vrije Universiteit Brussel (VUB), UZ-Brussel, Brussels, Belgium
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7
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Wang Q, Zhao Z, Shen H, Bing Q, Li N, Hu J. The Clinical, Myopathological, and Genetic Analysis of 20 Patients With Non-dystrophic Myotonia. Front Neurol 2022; 13:830707. [PMID: 35350395 PMCID: PMC8957821 DOI: 10.3389/fneur.2022.830707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 01/25/2022] [Indexed: 11/29/2022] Open
Abstract
Introduction Non-dystrophic myotonias (NDMs) are skeletal muscle ion channelopathies caused by CLCN1 or SCN4A mutations. This study aimed to describe the clinical, myopathological, and genetic analysis of NDM in a large Chinese cohort. Methods We reviewed the clinical manifestations, laboratory results, electrocardiogram, electromyography, muscle biopsy, genetic analysis, treatment, and follow-up of 20 patients (from 18 families) with NDM. Results Cases included myotonia congenita (MC, 17/20) and paramyotonia congenita (PMC, 3/20). Muscle stiffness and hypertrophy, grip and percussion myotonia, and the warm-up phenomenon were frequently observed in MC and PMC patients. Facial stiffness, eye closure myotonia, and cold sensitivity were more common in PMC patients and could be accompanied by permanent weakness. Nine MC patients and two PMC patients had cardiac abnormalities, mainly manifested as cardiac arrhythmia, and the father of one patient died of sudden cardiac arrest. Myotonic runs in electromyography were found in all patients, and seven MC patients had mild myopathic changes. There was no difference in muscle pathology between MC and PMC patients, most of whom had abnormal muscle fiber type distribution or selective muscle fiber atrophy. Nineteen CLCN1 variants were found in 17 MC patients, among which c.795T>G (p.D265E) was a new variant, and two SCN4A variants were found in three PMC patients. The patients were treated with mexiletine and/or carbamazepine, and the symptoms of myotonia were partially improved. Conclusions MC and PMC have considerable phenotypic overlap. Genetic investigation contributes to identifying the subtype of NDM. The muscle pathology of NDM lacks specific changes.
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Affiliation(s)
- Quanquan Wang
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, China.,Department of Neurology, Qilu Hospital of Shandong University, Qingdao, China
| | - Zhe Zhao
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Hongrui Shen
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Qi Bing
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Nan Li
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, China
| | - Jing Hu
- Department of Neuromuscular Disorders, The Third Hospital of Hebei Medical University, Shijiazhuang, China
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8
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Martinez‐Hernandez E, Blatter LA, Kanaporis G. L-type Ca 2+ channel recovery from inactivation in rabbit atrial myocytes. PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS 2022; 10:e15222. [PMID: 35274829 PMCID: PMC8915713 DOI: 10.14814/phy2.15222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 02/07/2022] [Accepted: 02/16/2022] [Indexed: 01/27/2023]
Abstract
Adaptation of the myocardium to varying workloads critically depends on the recovery from inactivation (RFI) of L-type Ca2+ channels (LCCs) which provide the trigger for cardiac contraction. The goal of the present study was a comprehensive investigation of LCC RFI in atrial myocytes. The study was performed on voltage-clamped rabbit atrial myocytes using a double pulse protocol with variable diastolic intervals in cells held at physiological holding potentials, with intact intracellular Ca2+ release, and preserved Na+ current and Na+ /Ca2+ exchanger (NCX) activity. We demonstrate that the kinetics of RFI of LCCs are co-regulated by several factors including resting membrane potential, [Ca2+ ]i , Na+ influx, and activity of CaMKII. In addition, activation of CaMKII resulted in increased ICa amplitude at higher pacing rates. Pharmacological inhibition of NCX failed to have any significant effect on RFI, indicating that impaired removal of Ca2+ by NCX has little effect on LCC recovery. Finally, RFI of intracellular Ca2+ release was substantially slower than LCC RFI, suggesting that inactivation kinetics of LCC do not significantly contribute to the beat-to-beat refractoriness of SR Ca2+ release. The study demonstrates that CaMKII and intracellular Ca2+ dynamics play a central role in modulation of LCC activity in atrial myocytes during increased workloads that could have important consequences under pathological conditions such as atrial fibrillations, where Ca2+ cycling and CaMKII activity are altered.
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Affiliation(s)
| | - Lothar A. Blatter
- Department of Physiology & BiophysicsRush University Medical CenterChicagoIllinoisUSA
| | - Giedrius Kanaporis
- Department of Physiology & BiophysicsRush University Medical CenterChicagoIllinoisUSA
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9
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Nicole S, Lory P. New Challenges Resulting From the Loss of Function of Na v1.4 in Neuromuscular Diseases. Front Pharmacol 2021; 12:751095. [PMID: 34671263 PMCID: PMC8521073 DOI: 10.3389/fphar.2021.751095] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 09/16/2021] [Indexed: 11/13/2022] Open
Abstract
The voltage-gated sodium channel Nav1.4 is a major actor in the excitability of skeletal myofibers, driving the muscle force in response to nerve stimulation. Supporting further this key role, mutations in SCN4A, the gene encoding the pore-forming α subunit of Nav1.4, are responsible for a clinical spectrum of human diseases ranging from muscle stiffness (sodium channel myotonia, SCM) to muscle weakness. For years, only dominantly-inherited diseases resulting from Nav1.4 gain of function (GoF) were known, i.e., non-dystrophic myotonia (delayed muscle relaxation due to myofiber hyperexcitability), paramyotonia congenita and hyperkalemic or hypokalemic periodic paralyses (episodic flaccid muscle weakness due to transient myofiber hypoexcitability). These last 5 years, SCN4A mutations inducing Nav1.4 loss of function (LoF) were identified as the cause of dominantly and recessively-inherited disorders with muscle weakness: periodic paralyses with hypokalemic attacks, congenital myasthenic syndromes and congenital myopathies. We propose to name this clinical spectrum sodium channel weakness (SCW) as the mirror of SCM. Nav1.4 LoF as a cause of permanent muscle weakness was quite unexpected as the Na+ current density in the sarcolemma is large, securing the ability to generate and propagate muscle action potentials. The properties of SCN4A LoF mutations are well documented at the channel level in cellular electrophysiological studies However, much less is known about the functional consequences of Nav1.4 LoF in skeletal myofibers with no available pertinent cell or animal models. Regarding the therapeutic issues for Nav1.4 channelopathies, former efforts were aimed at developing subtype-selective Nav channel antagonists to block myofiber hyperexcitability. Non-selective, Nav channel blockers are clinically efficient in SCM and paramyotonia congenita, whereas patient education and carbonic anhydrase inhibitors are helpful to prevent attacks in periodic paralyses. Developing therapeutic tools able to counteract Nav1.4 LoF in skeletal muscles is then a new challenge in the field of Nav channelopathies. Here, we review the current knowledge regarding Nav1.4 LoF and discuss the possible therapeutic strategies to be developed in order to improve muscle force in SCW.
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Affiliation(s)
- Sophie Nicole
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics (ICST), Montpellier, France
| | - Philippe Lory
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, France.,LabEx 'Ion Channel Science and Therapeutics (ICST), Montpellier, France
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10
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Chen L, He Y, Wang X, Ge J, Li H. Ventricular voltage-gated ion channels: Detection, characteristics, mechanisms, and drug safety evaluation. Clin Transl Med 2021; 11:e530. [PMID: 34709746 PMCID: PMC8516344 DOI: 10.1002/ctm2.530] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 02/06/2023] Open
Abstract
Cardiac voltage-gated ion channels (VGICs) play critical roles in mediating cardiac electrophysiological signals, such as action potentials, to maintain normal heart excitability and contraction. Inherited or acquired alterations in the structure, expression, or function of VGICs, as well as VGIC-related side effects of pharmaceutical drug delivery can result in abnormal cellular electrophysiological processes that induce life-threatening cardiac arrhythmias or even sudden cardiac death. Hence, to reduce possible heart-related risks, VGICs must be acknowledged as important targets in drug discovery and safety studies related to cardiac disease. In this review, we first summarize the development and application of electrophysiological techniques that are employed in cardiac VGIC studies alone or in combination with other techniques such as cryoelectron microscopy, optical imaging and optogenetics. Subsequently, we describe the characteristics, structure, mechanisms, and functions of various well-studied VGICs in ventricular myocytes and analyze their roles in and contributions to both physiological cardiac excitability and inherited cardiac diseases. Finally, we address the implications of the structure and function of ventricular VGICs for drug safety evaluation. In summary, multidisciplinary studies on VGICs help researchers discover potential targets of VGICs and novel VGICs in heart, enrich their knowledge of the properties and functions, determine the operation mechanisms of pathological VGICs, and introduce groundbreaking trends in drug therapy strategies, and drug safety evaluation.
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Affiliation(s)
- Lulan Chen
- Department of Cardiology, Shanghai Institute of Cardiovascular DiseasesShanghai Xuhui District Central Hospital & Zhongshan‐xuhui Hospital, Zhongshan Hospital, Fudan UniversityShanghaiChina
| | - Yue He
- Department of CardiologyShanghai Xuhui District Central Hospital & Zhongshan‐xuhui HospitalShanghaiChina
| | - Xiangdong Wang
- Institute of Clinical Science, Zhongshan HospitalFudan UniversityShanghaiChina
| | - Junbo Ge
- Department of Cardiology, Shanghai Institute of Cardiovascular DiseasesShanghai Xuhui District Central Hospital & Zhongshan‐xuhui Hospital, Zhongshan Hospital, Fudan UniversityShanghaiChina
| | - Hua Li
- Department of Cardiology, Shanghai Institute of Cardiovascular DiseasesShanghai Xuhui District Central Hospital & Zhongshan‐xuhui Hospital, Zhongshan Hospital, Fudan UniversityShanghaiChina
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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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Abstract
Long QT syndrome (LQTS) is a cardiovascular disorder characterized by an abnormality in cardiac repolarization leading to a prolonged QT interval and T-wave irregularities on the surface electrocardiogram. It is commonly associated with syncope, seizures, susceptibility to torsades de pointes, and risk for sudden death. LQTS is a rare genetic disorder and a major preventable cause of sudden cardiac death in the young. The availability of therapy for this lethal disease emphasizes the importance of early and accurate diagnosis. Additionally, understanding of the molecular mechanisms underlying LQTS could help to optimize genotype-specific treatments to prevent deaths in LQTS patients. In this review, we briefly summarize current knowledge regarding molecular underpinning of LQTS, in particular focusing on LQT1, LQT2, and LQT3, and discuss novel strategies to study ion channel dysfunction and drug-specific therapies in LQT1, LQT2, and LQT3 syndromes.
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Affiliation(s)
| | - Isabelle Deschênes
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio
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13
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Llongueras JP, Das S, De Waele J, Capulzini L, Sorgente A, Van Petegem F, Bosmans F. Biophysical Investigation of Sodium Channel Interaction with β-Subunit Variants Associated with Arrhythmias. Bioelectricity 2020; 2:269-278. [PMID: 34476357 DOI: 10.1089/bioe.2020.0030] [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] [Indexed: 12/13/2022] Open
Abstract
Background: Voltage-gated sodium (NaV) channels help regulate electrical activity of the plasma membrane. Mutations in associated subunits can result in pathological outcomes. Here we examined the interaction of NaV channels with cardiac arrhythmia-linked mutations in SCN2B and SCN4B, two genes that encode auxiliary β-subunits. Materials and Methods: To investigate changes in SCN2B R137H and SCN4B I80T function, we combined three-dimensional X-ray crystallography with electrophysiological measurements on NaV1.5, the dominant subtype in the heart. Results: SCN4B I80T alters channel activity, whereas SCN2B R137H does not have an apparent effect. Structurally, the SCN4B I80T perturbation alters hydrophobic packing of the subunit with major structural changes and causes a thermal destabilization of the folding. In contrast, SCN2B R137H leads to structural changes but overall protein stability is unaffected. Conclusion: SCN4B I80T data suggest a functionally important region in the interaction between NaV1.5 and β4 that, when disrupted, could lead to channel dysfunction. A lack of apparent functional effects of SCN2B R137H on NaV1.5 suggests an alternative working mechanism, possibly through other NaV channel subtypes present in heart tissue. Indeed, mapping the structural variations of SCN2B R137H onto neuronal NaV channel structures suggests altered interaction patterns.
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Affiliation(s)
- José P Llongueras
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Samir Das
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.,Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Jolien De Waele
- Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Lucio Capulzini
- Arrhythmia and Electrophysiology Center, Department of Cardiology, Epicura Hospitalier Center, Hornu, Belgium
| | - Antonio Sorgente
- Arrhythmia and Electrophysiology Center, Department of Cardiology, Epicura Hospitalier Center, Hornu, Belgium
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.,Life Sciences Institute, University of British Columbia, Vancouver, Canada
| | - Frank Bosmans
- Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
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14
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Williams AL, Khadka VS, Anagaran MCT, Lee K, Avelar A, Deng Y, Shohet RV. miR-125 family regulates XIRP1 and FIH in response to myocardial infarction. Physiol Genomics 2020; 52:358-368. [PMID: 32716698 DOI: 10.1152/physiolgenomics.00041.2020] [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] [Indexed: 12/19/2022] Open
Abstract
MicroRNAs (miRNAs) are powerful regulators of protein expression. Many play important roles in cardiac development and disease. While several miRNAs and targets have been well characterized, the abundance of miRNAs and the numerous potential targets for each suggest that the vast majority of these interactions have yet to be described. The goal of this study was to characterize miRNA expression in the mouse heart after coronary artery ligation (LIG) and identify novel mRNA targets altered during the initial response to ischemic stress. We performed small RNA sequencing (RNA-Seq) of ischemic heart tissue 1 day and 3 days after ligation and identified 182 differentially expressed miRNAs. We then selected relevant mRNA targets from all potential targets by correlating miRNA and mRNA expression from a corresponding RNA-Seq data set. From this analysis we chose to focus, as proof of principle, on two miRNAs from the miR-125 family, miR-125a and miR-351, and two of their potential mRNA targets, Xin actin-binding repeat-containing protein 1 (XIRP1) and factor inhibiting hypoxia-inducible factor (FIH). We found miR-125a to be less abundant and XIRP1 more abundant after ligation. In contrast, the related murine miRNA miR-351 was substantially upregulated in response to ischemic injury, and FIH expression correspondingly decreased. Luciferase reporter assays confirmed direct interactions between these miRNAs and targets. In summary, we utilized a correlative analysis strategy combining miRNA and mRNA expression data to identify functional miRNA-mRNA relationships in the heart after ligation. These findings provide insight into the response to ischemic injury and suggest future therapeutic targets.
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Affiliation(s)
- Allison Lesher Williams
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Vedbar S Khadka
- Bioinformatics Core, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Ma C T Anagaran
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Katie Lee
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Abigail Avelar
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Youping Deng
- Bioinformatics Core, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
| | - Ralph V Shohet
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii
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15
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Isaac E, Cooper SM, Jones SA, Loubani M. Do age-associated changes of voltage-gated sodium channel isoforms expressed in the mammalian heart predispose the elderly to atrial fibrillation? World J Cardiol 2020; 12:123-135. [PMID: 32431783 PMCID: PMC7215965 DOI: 10.4330/wjc.v12.i4.123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 01/18/2020] [Accepted: 03/15/2020] [Indexed: 02/06/2023] Open
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia worldwide. The prevalence of the disease increases with age, strongly implying an age-related process underlying the pathology. At a time when people are living longer than ever before, an exponential increase in disease prevalence is predicted worldwide. Hence unraveling the underlying mechanics of the disease is paramount for the development of innovative treatment and prevention strategies. The role of voltage-gated sodium channels is fundamental in cardiac electrophysiology and may provide novel insights into the arrhythmogenesis of AF. Nav1.5 is the predominant cardiac isoform, responsible for the action potential upstroke. Recent studies have demonstrated that Nav1.8 (an isoform predominantly expressed within the peripheral nervous system) is responsible for cellular arrhythmogenesis through the enhancement of pro-arrhythmogenic currents. Animal studies have shown a decline in Nav1.5 leading to a diminished action potential upstroke during phase 0. Furthermore, the study of human tissue demonstrates an inverse expression of sodium channel isoforms; reduction of Nav1.5 and increase of Nav1.8 in both heart failure and ventricular hypertrophy. This strongly suggests that the expression of voltage-gated sodium channels play a crucial role in the development of arrhythmias in the diseased heart. Targeting aberrant sodium currents has led to novel therapeutic approaches in tackling AF and continues to be an area of emerging research. This review will explore how voltage-gated sodium channels may predispose the elderly heart to AF through the examination of laboratory and clinical based evidence.
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Affiliation(s)
- Emmanuel Isaac
- Department of Cardiothoracic Surgery, Hull University Teaching Hospitals, Cottingham HU16 5JQ, United Kingdom
| | - Stephanie M Cooper
- Department of Biomedical Sciences, University of Hull, Hull HU6 7RX, United Kingdom
| | - Sandra A Jones
- Department of Biomedical Sciences, University of Hull, Hull HU6 7RX, United Kingdom
| | - Mahmoud Loubani
- Department of Cardiothoracic Surgery, Hull University Teaching Hospitals, Cottingham HU16 5JQ, United Kingdom
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16
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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: 28] [Impact Index Per Article: 7.0] [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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17
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Li Q, Zhai Z, Li J. Fibroblast growth factor homologous factors are potential ion channel modifiers associated with cardiac arrhythmias. Eur J Pharmacol 2020; 871:172920. [PMID: 31935396 DOI: 10.1016/j.ejphar.2020.172920] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 12/10/2019] [Accepted: 01/10/2020] [Indexed: 12/27/2022]
Abstract
Stable electrical activity in cardiac myocytes is the basis of maintaining normal myocardial systolic and diastolic function. Cardiac ionic currents and their associated regulatory proteins are crucial to myocyte excitability and heart function. Fibroblast growth factor homologous factors (FHFs) are intracellular noncanonical fibroblast growth factors (FGFs) that are incapable of activating FGF receptors. The main functions of FHFs are to regulate ion channels and influence excitability, which are processes involved in sustaining normal cardiac function. In addition to their regulatory effect on ion channels, FHFs can be regulators of cardiac hypertrophic signaling and alter signaling pathways, including the protein kinase, NF<kappa>B, and p53 pathways, which are related to the pathological processes of heart diseases. This review emphasizes FHF-mediated regulation of cardiac excitability and the association of FHFs with cardiac arrhythmias and explores the idea that abnormal FHFs may be an unrecognized cause of cardiac disorders.
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Affiliation(s)
- Qing Li
- Department of Cardiovascular Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang, 330006, China
| | - Zhenyu Zhai
- Department of Cardiovascular Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang, 330006, China
| | - Juxiang Li
- Department of Cardiovascular Medicine, The Second Affiliated Hospital of Nanchang University, Nanchang, 330006, China.
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18
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Maroni M, Körner J, Schüttler J, Winner B, Lampert A, Eberhardt E. β1 and β3 subunits amplify mechanosensitivity of the cardiac voltage-gated sodium channel Nav1.5. Pflugers Arch 2019; 471:1481-1492. [PMID: 31728700 DOI: 10.1007/s00424-019-02324-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 09/25/2019] [Accepted: 10/21/2019] [Indexed: 12/19/2022]
Abstract
In cardiomyocytes, electrical activity is coupled to cellular contraction, thus exposing all proteins expressed in the sarcolemma to mechanical stress. The voltage-gated sodium channel Nav1.5 is the main contributor to the rising phase of the action potential in the heart. There is growing evidence that gating and kinetics of Nav1.5 are modulated by mechanical forces and pathogenic variants that affect mechanosensitivity have been linked to arrhythmias. Recently, the sodium channel β1 subunit has been described to stabilise gating against mechanical stress of Nav1.7 expressed in neurons. Here, we tested the effect of β1 and β3 subunits on mechanosensitivity of the cardiac Nav1.5. β1 amplifies stress-induced shifts of V1/2 of steady-state fast inactivation to hyperpolarised potentials (ΔV1/2: 6.2 mV without and 10.7 mV with β1 co-expression). β3, on the other hand, almost doubles stress-induced speeding of time to sodium current transient peak (Δtime to peak at - 30 mV: 0.19 ms without and 0.37 ms with β3 co-expression). Our findings may indicate that in cardiomyocytes, the interdependence of electrical activity and contraction is used as a means of fine tuning cardiac sodium channel function, allowing quicker but more strongly inactivating sodium currents under conditions of increased mechanical stress. This regulation may help to shorten action potential duration during tachycardia, to prevent re-entry phenomena and thus arrhythmias.
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Affiliation(s)
- Michele Maroni
- Department of Anaesthesiology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany.,Department of Stem Cell Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Jannis Körner
- Institute of Physiology, Medical Faculty, RWTH Aachen University, 52074, Aachen, Germany.,Department of Anaesthesiology, Medical Faculty, RWTH Aachen University, 52074, Aachen, Germany
| | - Jürgen Schüttler
- Department of Anaesthesiology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Beate Winner
- Department of Stem Cell Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany
| | - Angelika Lampert
- Institute of Physiology, Medical Faculty, RWTH Aachen University, 52074, Aachen, Germany
| | - Esther Eberhardt
- Department of Anaesthesiology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054, Erlangen, Germany.
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19
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Sodium Channel Nav1.3 Is Expressed by Polymorphonuclear Neutrophils during Mouse Heart and Kidney Ischemia In Vivo and Regulates Adhesion, Transmigration, and Chemotaxis of Human and Mouse Neutrophils In Vitro. Anesthesiology 2019; 128:1151-1166. [PMID: 29509584 DOI: 10.1097/aln.0000000000002135] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Voltage-gated sodium channels generate action potentials in excitable cells, but they have also been attributed noncanonical roles in nonexcitable cells. We hypothesize that voltage-gated sodium channels play a functional role during extravasation of neutrophils. METHODS Expression of voltage-gated sodium channels was analyzed by polymerase chain reaction. Distribution of Nav1.3 was determined by immunofluorescence and flow cytometry in mouse models of ischemic heart and kidney injury. Adhesion, transmigration, and chemotaxis of neutrophils to endothelial cells and collagen were investigated with voltage-gated sodium channel inhibitors and lidocaine in vitro. Sodium currents were examined with a whole cell patch clamp. RESULTS Mouse and human neutrophils express multiple voltage-gated sodium channels. Only Nav1.3 was detected in neutrophils recruited to ischemic mouse heart (25 ± 7%, n = 14) and kidney (19 ± 2%, n = 6) in vivo. Endothelial adhesion of mouse neutrophils was reduced by tetrodotoxin (56 ± 9%, unselective Nav-inhibitor), ICA121431 (53 ± 10%), and Pterinotoxin-2 (55 ± 9%; preferential inhibitors of Nav1.3, n = 10). Tetrodotoxin (56 ± 19%), ICA121431 (62 ± 22%), and Pterinotoxin-2 (59 ± 22%) reduced transmigration of human neutrophils through endothelial cells, and also prevented chemotactic migration (n = 60, 3 × 20 cells). Lidocaine reduced neutrophil adhesion to 60 ± 9% (n = 10) and transmigration to 54 ± 8% (n = 9). The effect of lidocaine was not increased by ICA121431 or Pterinotoxin-2. CONCLUSIONS Nav1.3 is expressed in neutrophils in vivo; regulates attachment, transmigration, and chemotaxis in vitro; and may serve as a relevant target for antiinflammatory effects of lidocaine.
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20
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Chu L, Greenstein JL, Winslow RL. Na + microdomains and sparks: Role in cardiac excitation-contraction coupling and arrhythmias in ankyrin-B deficiency. J Mol Cell Cardiol 2019; 128:145-157. [PMID: 30731085 DOI: 10.1016/j.yjmcc.2019.02.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 02/01/2019] [Accepted: 02/02/2019] [Indexed: 01/25/2023]
Abstract
Cardiac sodium (Na+) potassium ATPase (NaK) pumps, neuronal sodium channels (INa), and sodium calcium (Ca2+) exchangers (NCX1) may co-localize to form a Na+ microdomain. It remains controversial as to whether neuronal INa contributes to local Na+ accumulation, resulting in reversal of nearby NCX1 and influx of Ca2+ into the cell. Therefore, there has been great interest in the possible roles of a Na+ microdomain in cardiac Ca2+-induced Ca2+ release (CICR). In addition, the important role of co-localization of NaK and NCX1 in regulating localized Na+ and Ca2+ levels and CICR in ankyrin-B deficient (ankyrin-B+/-) cardiomyocytes has been examined in many recent studies. Altered Na+ dynamics may contribute to the appearance of arrhythmias, but the mechanisms underlying this relationship remain unclear. In order to investigate this, we present a mechanistic canine cardiomyocyte model which reproduces independent local dyadic junctional SR (JSR) Ca2+ release events underlying cell-wide excitation-contraction coupling, as well as a three-dimensional super-resolution model of the Ca2+ spark that describes local Na+ dynamics as governed by NaK pumps, neuronal INa, and NCX1. The model predicts the existence of Na+ sparks, which are generated by NCX1 and exhibit significantly slower dynamics as compared to Ca2+ sparks. Moreover, whole-cell simulations indicate that neuronal INa in the cardiac dyad plays a key role during the systolic phase. Rapid inward neuronal INa can elevate dyadic [Na+] to 35-40 mM, which drives reverse-mode NCX1 transport, and therefore promotes Ca2+ entry into the dyad, enhancing the trigger for JSR Ca2+ release. The specific role of decreased co-localization of NaK and NCX1 in ankyrin-B+/- cardiomyocytes was examined. Model results demonstrate that a reduction in the local NCX1- and NaK-mediated regulation of dyadic [Ca2+] and [Na+] results in an increase in Ca2+ spark activity during isoproterenol stimulation, which in turn stochastically activates NCX1 in the dyad. This alteration in NCX1/NaK co-localization interrupts the balance between NCX1 and NaK currents in a way that leads to enhanced depolarizing inward current during the action potential plateau, which ultimately leads to a higher probability of L-type Ca2+ channel reopening and arrhythmogenic early-afterdepolarizations.
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Affiliation(s)
- Lulu Chu
- Department of Biomedical Engineering and the Institute for Computational Medicine, The Johns Hopkins University School of Medicine and Whiting School of Engineering, 3400 N Charles Street, Baltimore, MD 21218, USA.
| | - Joseph L Greenstein
- Department of Biomedical Engineering and the Institute for Computational Medicine, The Johns Hopkins University School of Medicine and Whiting School of Engineering, 3400 N Charles Street, Baltimore, MD 21218, USA.
| | - Raimond L Winslow
- Department of Biomedical Engineering and the Institute for Computational Medicine, The Johns Hopkins University School of Medicine and Whiting School of Engineering, 3400 N Charles Street, Baltimore, MD 21218, USA.
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21
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Wang W, Mellor RL, Nerbonne JM, Balke CW. Regional differences in the expression of tetrodotoxin-sensitive inward Ca 2+ and outward Cs +/K + currents in mouse and human ventricles. Channels (Austin) 2019; 13:72-87. [PMID: 30704344 PMCID: PMC6380286 DOI: 10.1080/19336950.2019.1568146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Tetrodotoxin (TTX) sensitive inward Ca2+ currents, ICa(TTX), have been identified in cardiac myocytes from several species, although it is unclear if ICa(TTX) is expressed in all cardiac cell types, and if ICa(TTX) reflects Ca2+ entry through the main, Nav1.5-encoded, cardiac Na+ (Nav) channels. To address these questions, recordings were obtained with 2 mm Ca2+ and 0 mm Na+ in the bath and 120 mm Cs+ in the pipettes from myocytes isolated from adult mouse interventricular septum (IVS), left ventricular (LV) endocardium, apex, and epicardium and from human LV endocardium and epicardium. On membrane depolarizations from a holding potential of −100 mV, ICa(TTX) was identified in mouse IVS and LV endocardial myocytes and in human LV endocardial myocytes, whereas only TTX-sensitive outward Cs+/K+ currents were observed in mouse LV apex and epicardial myocytes and human LV epicardial myocytes. The inward Ca2+, but not the outward Cs+/K+, currents were blocked by mm concentrations of MTSEA, a selective blocker of cardiac Nav1.5-encoded Na+ channels. In addition, in Nav1.5-expressing tsA-201 cells, ICa(TTX) was observed in 3 (of 20) cells, and TTX-sensitive outward Cs+/K+ currents were observed in the other (17) cells. The time- and voltage-dependent properties of the TTX-sensitive inward Ca2+ and outward Cs+/K+ currents recorded in Nav1.5-expressing tsA-201 were indistinguishable from native currents in mouse and human cardiac myocytes. Overall, the results presented here suggest marked regional, cell type-specific, differences in the relative ion selectivity, and likely the molecular architecture, of native SCN5A-/Scn5a- (Nav1.5-) encoded cardiac Na+ channels in mouse and human ventricles.
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Affiliation(s)
- Wei Wang
- a Center for Cardiovascular Research, Department of Medicine, Cardiovascular Division , Washington University School of Medicine , St. Louis , MO , USA
| | - Rebecca L Mellor
- a Center for Cardiovascular Research, Department of Medicine, Cardiovascular Division , Washington University School of Medicine , St. Louis , MO , USA
| | - Jeanne M Nerbonne
- a Center for Cardiovascular Research, Department of Medicine, Cardiovascular Division , Washington University School of Medicine , St. Louis , MO , USA.,b John Cochran Veterans Administration Medical Center , St. Louis , MO , USA
| | - C William Balke
- a Center for Cardiovascular Research, Department of Medicine, Cardiovascular Division , Washington University School of Medicine , St. Louis , MO , USA.,b John Cochran Veterans Administration Medical Center , St. Louis , MO , USA
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22
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Canine and human sinoatrial node: differences and similarities in the structure, function, molecular profiles, and arrhythmia. J Vet Cardiol 2018; 22:2-19. [PMID: 30559056 DOI: 10.1016/j.jvc.2018.10.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 10/02/2018] [Accepted: 10/02/2018] [Indexed: 12/17/2022]
Abstract
The sinoatrial node (SAN) is the primary pacemaker in canine and human hearts. The SAN in both species has a unique three-dimensional heterogeneous structure characterized by small pacemaker myocytes enmeshed within fibrotic strands, which partially insulate the cells from aberrant atrial activation. The SAN pacemaker tissue expresses a unique signature of proteins and receptors that mediate SAN automaticity, ion channel currents, and cell-to-cell communication, which are predominantly similar in both species. Recent intramural optical mapping, integrated with structural and molecular studies, has revealed the existence of up to five specialized SAN conduction pathways that preferentially conduct electrical activation to atrial tissues. The intrinsic heart rate, intranodal leading pacemaker shifts, and changes in conduction in response to physiological and pathophysiological stimuli are similar. Structural and/or functional impairments due to cardiac diseases including heart failure cause SAN dysfunctions (SNDs) in both species. These dysfunctions are usually manifested as severe bradycardia, tachy-brady arrhythmias, and conduction abnormalities including exit block and SAN reentry, which could lead to atrial tachycardia and fibrillation, cardiac arrest, and heart failure. Pharmaceutical drugs and implantable pacemakers are only partially successful in managing SNDs, emphasizing a critical need to develop targeted mechanism-based therapies to treat SNDs. Because several structural and functional characteristics are similar between the canine and human SAN, research in these species may be mutually beneficial for developing novel treatment approaches. This review describes structural, functional, and molecular similarities and differences between the canine and human SAN, with special emphasis on arrhythmias and unique causal mechanisms of SND in diseased hearts.
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23
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Rubart M. The coronary sinus: Novel arrhythmogenic aspects. J Cardiovasc Electrophysiol 2018; 30:239-241. [PMID: 30427094 DOI: 10.1111/jce.13787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 11/05/2018] [Indexed: 11/28/2022]
Affiliation(s)
- Michael Rubart
- Department of Pediatrics, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
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24
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Cavalli M, Fossati B, Vitale R, Brigonzi E, Ricigliano VAG, Saraceno L, Cardani R, Pappone C, Meola G. Flecainide-Induced Brugada Syndrome in a Patient With Skeletal Muscle Sodium Channelopathy: A Case Report With Critical Therapeutical Implications and Review of the Literature. Front Neurol 2018; 9:385. [PMID: 29899727 PMCID: PMC5988887 DOI: 10.3389/fneur.2018.00385] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/11/2018] [Indexed: 12/31/2022] Open
Abstract
Skeletal muscle sodium channelopathies are a group of neuromuscular disorders associated with mutations in the SCN4A gene. Because principal sodium channel isoforms expressed in the skeletal muscles and the heart are distinct one from the other, this condition usually spares cardiac functioning. Nonetheless, evidence on a possible link between skeletal muscle and cardiac sodium channelopathies has emerged in recent years. To date, eight patients bearing pathogenetic mutations in the SCN4A gene and manifesting cardiac electrophysiological alterations have been reported in literature. Among these patients, three presented a phenotype compatible with Brugada syndrome. We report the case of a 29-year-old patient affected by non-dystrophic myotonia associated with a p.G1306E mutation in the SCN4A gene, who presented symptoms of syncope and palpitation after the introduction of flecainide as an anti-myotonic agent. ECG and ajmaline challenge were consistent with the diagnosis of Brugada syndrome, leading to the implantation of a cardioverter defibrillator. No mutation in causative genes for Brugada syndrome was detected. Mexiletine treatment reduced myotonia without any cardiac adverse events. This case report highlights the clinical relevance of the recognition of cardiac electrophysiological alterations in skeletal muscle sodium channelopathies. The discovery of a possible pathogenetic linkage between skeletal muscle and cardiac sodium channelopathies may have significant implications in patients' management, also in light of the fact that class 1C anti-arrhythmics are potential triggers for life-threatening arrhythmias in patients with Brugada syndrome.
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Affiliation(s)
- Michele Cavalli
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Barbara Fossati
- Department of Neurology, IRCCS Policlinico San Donato, Milan, Italy
| | - Raffaele Vitale
- Clinical Arrhythmology and Electrophysiology Department, IRCCS Policlinico San Donato, Milan, Italy
| | - Elisa Brigonzi
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Vito A G Ricigliano
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Lorenzo Saraceno
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Rosanna Cardani
- Laboratory of Muscle Histopathology and Molecular Biology, IRCCS Policlinico San Donato, Milan, Italy
| | - Carlo Pappone
- Clinical Arrhythmology and Electrophysiology Department, IRCCS Policlinico San Donato, Milan, Italy
| | - Giovanni Meola
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy.,Department of Neurology, IRCCS Policlinico San Donato, Milan, Italy
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Savio-Galimberti E, Argenziano M, Antzelevitch C. Cardiac Arrhythmias Related to Sodium Channel Dysfunction. Handb Exp Pharmacol 2018; 246:331-354. [PMID: 28965168 DOI: 10.1007/164_2017_43] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The voltage-gated cardiac sodium channel (Nav1.5) is a mega-complex comprised of a pore-forming α subunit and 4 ancillary β-subunits together with numerous protein partners. Genetic defects in the form of rare variants in one or more sodium channel-related genes can cause a loss- or gain-of-function of sodium channel current (INa) leading to the manifestation of various disease phenotypes, including Brugada syndrome, long QT syndrome, progressive cardiac conduction disease, sick sinus syndrome, multifocal ectopic Purkinje-related premature contractions, and atrial fibrillation. Some sodium channelopathies have also been shown to be responsible for sudden infant death syndrome (SIDS). Although these genetic defects often present as pure electrical diseases, recent studies point to a contribution of structural abnormalities to the electrocardiographic and arrhythmic manifestation in some cases, such as dilated cardiomyopathy. The same rare variants in SCN5A or related genes may present with different clinical phenotypes in different individuals and sometimes in members of the same family. Genetic background and epigenetic and environmental factors contribute to the expression of these overlap syndromes. Our goal in this chapter is to review and discuss what is known about the clinical phenotype and genotype of each cardiac sodium channelopathy, and to briefly discuss the underlying mechanisms.
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Affiliation(s)
| | - Mariana Argenziano
- Lankenau Institute for Medical Research, 100 E. Lancaster Avenue, Wynnewood, PA, 19096, USA
| | - Charles Antzelevitch
- Lankenau Institute for Medical Research, 100 E. Lancaster Avenue, Wynnewood, PA, 19096, USA.
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26
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Dulsat G, Palomeras S, Cortada E, Riuró H, Brugada R, Vergés M. Trafficking and localisation to the plasma membrane of Nav1.5 promoted by the β2 subunit is defective due to a β2 mutation associated with Brugada syndrome. Biol Cell 2017; 109:273-291. [DOI: 10.1111/boc.201600085] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 05/14/2017] [Accepted: 05/31/2017] [Indexed: 12/11/2022]
Affiliation(s)
- Gemma Dulsat
- Cardiovascular Genetics Group; Girona Biomedical Research Institute (IDIBGI); Salt Girona 17190 Spain
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV); ISCIII Madrid 28029 Spain
| | - Sonia Palomeras
- Cardiovascular Genetics Group; Girona Biomedical Research Institute (IDIBGI); Salt Girona 17190 Spain
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV); ISCIII Madrid 28029 Spain
| | - Eric Cortada
- Cardiovascular Genetics Group; Girona Biomedical Research Institute (IDIBGI); Salt Girona 17190 Spain
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV); ISCIII Madrid 28029 Spain
| | - Helena Riuró
- Cardiovascular Genetics Group; Girona Biomedical Research Institute (IDIBGI); Salt Girona 17190 Spain
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV); ISCIII Madrid 28029 Spain
| | - Ramon Brugada
- Cardiovascular Genetics Group; Girona Biomedical Research Institute (IDIBGI); Salt Girona 17190 Spain
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV); ISCIII Madrid 28029 Spain
- Medical Sciences Department; University of Girona Medical School; Girona 17003 Spain
| | - Marcel Vergés
- Cardiovascular Genetics Group; Girona Biomedical Research Institute (IDIBGI); Salt Girona 17190 Spain
- Biomedical Research Networking Center on Cardiovascular Diseases (CIBERCV); ISCIII Madrid 28029 Spain
- Medical Sciences Department; University of Girona Medical School; Girona 17003 Spain
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Abstract
Voltage-gated sodium channels (VGSC) are critical determinants of cellular electrical activity through the control of initiation and propagation of action potential. To ensure this role, these proteins are not consistently delivered to the plasma membrane but undergo drastic quality controls throughout various adaptive processes such as biosynthesis, anterograde and retrograde trafficking, and membrane targeting. In pathological conditions, this quality control could lead to the retention of functional VGSC and is therefore the target of different pharmacological approaches. The present chapter gives an overview of the current understanding of the facets of VGSC life cycle in the context of both cardiac and neuronal cell types.
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Affiliation(s)
- A Mercier
- Laboratoire de Signalisation et Transports Ioniques Membranaires, Pôle Biologie Santé, Université de Poitiers, CNRS, 1 rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France
| | - P Bois
- Laboratoire de Signalisation et Transports Ioniques Membranaires, Pôle Biologie Santé, Université de Poitiers, CNRS, 1 rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France
| | - A Chatelier
- Laboratoire de Signalisation et Transports Ioniques Membranaires, Pôle Biologie Santé, Université de Poitiers, CNRS, 1 rue Georges Bonnet, TSA 51106, 86073, Poitiers Cedex 9, France.
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28
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Inhibitory effects of hesperetin on Nav1.5 channels stably expressed in HEK 293 cells and on the voltage-gated cardiac sodium current in human atrial myocytes. Acta Pharmacol Sin 2016; 37:1563-1573. [PMID: 27694909 DOI: 10.1038/aps.2016.97] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 07/31/2016] [Indexed: 12/19/2022] Open
Abstract
AIM Voltage-gated sodium channels composed of a pore-forming α subunit and auxiliary β subunits are responsible for the upstroke of the action potential in cardiac myocytes. The pore-forming subunit of the cardiac sodium channel Nav1.5, which is encoded by SCN5A, is the main ion channel that conducts the voltage-gated cardiac sodium current (INa) in cardiac cells. The current study sought to investigate the inhibitory effects of hesperetin on human cardiac Nav1.5 channels stably expressed in human embryonic kidney 293 (HEK 293) cells and on the voltage-gated cardiac sodium current (INa) in human atrial myocytes. METHODS The effects of hesperetin on human cardiac Nav1.5 channels expressed in HEK 293 cells and on cardiac Na+ currents in human atrial myocytes were examined through whole-cell patch-clamp techniques. RESULTS Nav1.5 currents were potently and reversibly suppressed in a concentration- and voltage-dependent manner by hesperetin, which exhibited an IC50 of 62.99 μmol/L. Hesperetin significantly and negatively shifted the voltage-dependent activation and inactivation curves. Hesperetin also markedly decelerated Nav1.5 current inactivation and slowed the recovery from Nav1.5 channel inactivation. The hesperetin-dependent blockage of Nav1.5 currents was frequency-dependent. Hesperetin also potently and reversibly inhibited Na+ current (INa) in human atrial myocytes, consistently with its effects on Nav1.5 currents in HEK 293 cells. CONCLUSION Hesperetin is a potent inhibitor of INa in human atrial myocytes and Nav1.5 channels expressed in human embryonic kidney 293 cells. Hesperetin probably functions by blocking the open state and the inactivated state of these channels.
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McKinnon D, Rosati B. Transmural gradients in ion channel and auxiliary subunit expression. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 122:165-186. [PMID: 27702655 DOI: 10.1016/j.pbiomolbio.2016.09.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/30/2016] [Indexed: 12/11/2022]
Abstract
Evolution has acted to shape the action potential in different regions of the heart in order to produce a maximally stable and efficient pump. This has been achieved by creating regional differences in ion channel expression levels within the heart as well as differences between equivalent cardiac tissues in different species. These region- and species-dependent differences in channel expression are established by regulatory evolution, evolution of the regulatory mechanisms that control channel expression levels. Ion channel auxiliary subunits are obvious targets for regulatory evolution, in order to change channel expression levels and/or modify channel function. This review focuses on the transmural gradients of ion channel expression in the heart and the role that regulation of auxiliary subunit expression plays in generating and shaping these gradients.
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Affiliation(s)
- David McKinnon
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Barbara Rosati
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, 11794, USA.
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30
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Barbuti A, Benzoni P, Campostrini G, Dell'Era P. Human derived cardiomyocytes: A decade of knowledge after the discovery of induced pluripotent stem cells. Dev Dyn 2016; 245:1145-1158. [DOI: 10.1002/dvdy.24455] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 05/05/2016] [Accepted: 05/05/2016] [Indexed: 12/27/2022] Open
Affiliation(s)
- Andrea Barbuti
- Department of Biosciences; Università degli Studi di Milano; Milan Italy
| | - Patrizia Benzoni
- Department of Biosciences; Università degli Studi di Milano; Milan Italy
| | - Giulia Campostrini
- Department of Biosciences; Università degli Studi di Milano; Milan Italy
| | - Patrizia Dell'Era
- Cellular Fate Reprogramming Unit, Department of Molecular and Translational Medicine; Università degli Studi di Brescia; Brescia Italy
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31
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Winters JJ, Isom LL. Developmental and Regulatory Functions of Na(+) Channel Non-pore-forming β Subunits. CURRENT TOPICS IN MEMBRANES 2016; 78:315-51. [PMID: 27586289 DOI: 10.1016/bs.ctm.2016.07.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Voltage-gated Na(+) channels (VGSCs) isolated from mammalian neurons are heterotrimeric complexes containing one pore-forming α subunit and two non-pore-forming β subunits. In excitable cells, VGSCs are responsible for the initiation of action potentials. VGSC β subunits are type I topology glycoproteins, containing an extracellular amino-terminal immunoglobulin (Ig) domain with homology to many neural cell adhesion molecules (CAMs), a single transmembrane segment, and an intracellular carboxyl-terminal domain. VGSC β subunits are encoded by a gene family that is distinct from the α subunits. While α subunits are expressed in prokaryotes, β subunit orthologs did not arise until after the emergence of vertebrates. β subunits regulate the cell surface expression, subcellular localization, and gating properties of their associated α subunits. In addition, like many other Ig-CAMs, β subunits are involved in cell migration, neurite outgrowth, and axon pathfinding and may function in these roles in the absence of associated α subunits. In sum, these multifunctional proteins are critical for both channel regulation and central nervous system development.
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Affiliation(s)
- J J Winters
- University of Michigan Neuroscience Program, Ann Arbor, MI, United States
| | - L L Isom
- University of Michigan Neuroscience Program, Ann Arbor, MI, United States; University of Michigan Medical School, Ann Arbor, MI, United States
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32
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Mannhardt I, Breckwoldt K, Letuffe-Brenière D, Schaaf S, Schulz H, Neuber C, Benzin A, Werner T, Eder A, Schulze T, Klampe B, Christ T, Hirt MN, Huebner N, Moretti A, Eschenhagen T, Hansen A. Human Engineered Heart Tissue: Analysis of Contractile Force. Stem Cell Reports 2016; 7:29-42. [PMID: 27211213 PMCID: PMC4944531 DOI: 10.1016/j.stemcr.2016.04.011] [Citation(s) in RCA: 250] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 04/20/2016] [Accepted: 04/22/2016] [Indexed: 02/06/2023] Open
Abstract
Analyzing contractile force, the most important and best understood function of cardiomyocytes in vivo is not established in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM). This study describes the generation of 3D, strip-format, force-generating engineered heart tissues (EHT) from hiPSC-CM and their physiological and pharmacological properties. CM were differentiated from hiPSC by a growth factor-based three-stage protocol. EHTs were generated and analyzed histologically and functionally. HiPSC-CM in EHTs showed well-developed sarcomeric organization and alignment, and frequent mitochondria. Systematic contractility analysis (26 concentration-response curves) reveals that EHTs replicated canonical response to physiological and pharmacological regulators of inotropy, membrane- and calcium-clock mediators of pacemaking, modulators of ion-channel currents, and proarrhythmic compounds with unprecedented precision. The analysis demonstrates a high degree of similarity between hiPSC-CM in EHT format and native human heart tissue, indicating that human EHTs are useful for preclinical drug testing and disease modeling. Engineered heart tissues (EHTs) from hiPSC-CM are generated with high reproducibility EHTs show aligned cardiomyocytes with organized sarcomeres and immature t tubules Spontaneous beating is regulated by both, membrane- and calcium-clock mechanisms EHTs respond to physiological and pharmacological interventions like human heart tissue
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Affiliation(s)
- Ingra Mannhardt
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Kaja Breckwoldt
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - David Letuffe-Brenière
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Sebastian Schaaf
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Herbert Schulz
- Max-Delbrueck-Center for Molecular Medicine - MDC, DZHK (German Center for Cardiovascular Research), Partner Site Berlin, 13092 Berlin, Germany; Cologne Center for Genomics (CCG), University of Cologne, 50931 Cologne, Germany
| | - Christiane Neuber
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Anika Benzin
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Tessa Werner
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Alexandra Eder
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Thomas Schulze
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Birgit Klampe
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Torsten Christ
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Marc N Hirt
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Norbert Huebner
- Max-Delbrueck-Center for Molecular Medicine - MDC, DZHK (German Center for Cardiovascular Research), Partner Site Berlin, 13092 Berlin, Germany
| | - Alessandra Moretti
- I. Medical Department - Cardiology, Klinikum rechts der Isar - Technische Universität München, DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, 81675 Munich, Germany
| | - Thomas Eschenhagen
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany
| | - Arne Hansen
- Department of Experimental Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, 20246 Hamburg, Germany.
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Tetrodotoxin-sensitive α-subunits of voltage-gated sodium channels are relevant for inhibition of cardiac sodium currents by local anesthetics. Naunyn Schmiedebergs Arch Pharmacol 2016; 389:625-36. [DOI: 10.1007/s00210-016-1231-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 03/10/2016] [Indexed: 01/25/2023]
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34
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Hasdemir C. Atrial arrhythmias in inherited arrhythmogenic disorders. J Arrhythm 2016; 32:366-372. [PMID: 27761160 PMCID: PMC5063273 DOI: 10.1016/j.joa.2015.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 11/17/2015] [Indexed: 12/19/2022] Open
Abstract
Atrial arrhythmias are being increasingly recognized in inherited arrhythmogenic disorders particularly in patients with Brugada syndrome and short QT syndrome. Atrial arrhythmias in inherited arrhythmogenic disorders have significant epidemiologic, clinical, and prognostic implications. There has been progress in the understanding of underlying genetic characteristics and the mechanistic link between atrial arrhythmias and inherited arrhythmogenic disorders. Appropriate management of these patients is of paramount importance.
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Affiliation(s)
- Can Hasdemir
- Department of Cardiology, Ege University School of Medicine, Bornova, Izmir 35100, Turkey
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35
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Mantuano A, Barroso RC, Nogueira LP, Colaço MV, Mota CL, Pickler A, Braz D, Salata C, Ferreira-Machado S, de Almeida CE, Gianoncelli A. Alterations in Low-Z Elements Distribution in Heart Tissue after Treatments to Breast Cancer Using LEXRF Technique. ACTA ACUST UNITED AC 2016. [DOI: 10.4236/ajac.2016.711068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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36
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Chen-Izu Y, Shaw RM, Pitt GS, Yarov-Yarovoy V, Sack JT, Abriel H, Aldrich RW, Belardinelli L, Cannell MB, Catterall WA, Chazin WJ, Chiamvimonvat N, Deschenes I, Grandi E, Hund TJ, Izu LT, Maier LS, Maltsev VA, Marionneau C, Mohler PJ, Rajamani S, Rasmusson RL, Sobie EA, Clancy CE, Bers DM. Na+ channel function, regulation, structure, trafficking and sequestration. J Physiol 2015; 593:1347-60. [PMID: 25772290 DOI: 10.1113/jphysiol.2014.281428] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 11/02/2014] [Indexed: 12/19/2022] Open
Abstract
This paper is the second of a series of three reviews published in this issue resulting from the University of California Davis Cardiovascular Symposium 2014: Systems approach to understanding cardiac excitation-contraction coupling and arrhythmias: Na(+) channel and Na(+) transport. The goal of the symposium was to bring together experts in the field to discuss points of consensus and controversy on the topic of sodium in the heart. The present review focuses on Na(+) channel function and regulation, Na(+) channel structure and function, and Na(+) channel trafficking, sequestration and complexing.
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Affiliation(s)
- Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, USA; Department of Biomedical Engineering, University of California, Davis, USA; Department of Internal Medicine/Cardiology, University of California, Davis, USA
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Abstract
Voltage-gated sodium channels (VGSCs) are responsible for the initiation and propagation of action potentials in excitable cells. VGSCs in mammalian brain are heterotrimeric complexes of α and β subunits. Although β subunits were originally termed auxiliary, we now know that they are multifunctional signaling molecules that play roles in both excitable and nonexcitable cell types and with or without the pore-forming α subunit present. β subunits function in VGSC and potassium channel modulation, cell adhesion, and gene regulation, with particularly important roles in brain development. Mutations in the genes encoding β subunits are linked to a number of diseases, including epilepsy, sudden death syndromes like SUDEP and SIDS, and cardiac arrhythmia. Although VGSC β subunit-specific drugs have not yet been developed, this protein family is an emerging therapeutic target.
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Affiliation(s)
- Heather A O'Malley
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan 48109;
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38
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Gintant G. Cardiac Sodium Current (Na v1.5). METHODS AND PRINCIPLES IN MEDICINAL CHEMISTRY 2015. [DOI: 10.1002/9783527673643.ch12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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39
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Bissay V, Van Malderen SCH, Keymolen K, Lissens W, Peeters U, Daneels D, Jansen AC, Pappaert G, Brugada P, De Keyser J, Van Dooren S. SCN4A variants and Brugada syndrome: phenotypic and genotypic overlap between cardiac and skeletal muscle sodium channelopathies. Eur J Hum Genet 2015; 24:400-7. [PMID: 26036855 DOI: 10.1038/ejhg.2015.125] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 04/03/2015] [Accepted: 05/06/2015] [Indexed: 12/19/2022] Open
Abstract
SCN5A mutations involving the α-subunit of the cardiac voltage-gated muscle sodium channel (NaV1.5) result in different cardiac channelopathies with an autosomal-dominant inheritance such as Brugada syndrome. On the other hand, mutations in SCN4A encoding the α-subunit of the skeletal voltage-gated sodium channel (NaV1.4) cause non-dystrophic myotonia and/or periodic paralysis. In this study, we investigated whether cardiac arrhythmias or channelopathies such as Brugada syndrome can be part of the clinical phenotype associated with SCN4A variants and whether patients with Brugada syndrome present with non-dystrophic myotonia or periodic paralysis and related gene mutations. We therefore screened seven families with different SCN4A variants and non-dystrophic myotonia phenotypes for Brugada syndrome and performed a neurological, neurophysiological and genetic work-up in 107 Brugada families. In the families with an SCN4A-associated non-dystrophic myotonia, three patients had a clinical diagnosis of Brugada syndrome, whereas we found a remarkably high prevalence of myotonic features involving different genes in the families with Brugada syndrome. One Brugada family carried an SCN4A variant that is predicted to probably affect function, one family suffered from a not genetically confirmed non-dystrophic myotonia, one family was diagnosed with myotonic dystrophy (DMPK gene) and one family had a Thomsen disease myotonia congenita (CLCN1 variant that affects function). Our findings and data suggest a possible involvement of SCN4A variants in the pathophysiological mechanism underlying the development of a spontaneous or drug-induced type 1 electrocardiographic pattern and the occurrence of malignant arrhythmias in some patients with Brugada syndrome.
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Affiliation(s)
- Véronique Bissay
- Department of Neurology, Center for Neurosciences, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Sophie C H Van Malderen
- Department of Cardiology, Heart Rhythm Management Center, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium.,Department of Electrophysiology, Thorax Center, Erasmus MC, Rotterdam, The Netherlands
| | - Kathelijn Keymolen
- Center for Medical Genetics, Reproduction and Genetics; Genetics and Regenerative Medicine, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Willy Lissens
- Center for Medical Genetics, Reproduction and Genetics; Genetics and Regenerative Medicine, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Uschi Peeters
- Center for Medical Genetics, Reproduction and Genetics; Genetics and Regenerative Medicine, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Dorien Daneels
- Center for Medical Genetics, Reproduction and Genetics; Genetics and Regenerative Medicine, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Anna C Jansen
- Pediatric Neurology Unit, Department of Pediatrics, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Gudrun Pappaert
- Department of Cardiology, Heart Rhythm Management Center, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Pedro Brugada
- Department of Cardiology, Heart Rhythm Management Center, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Jacques De Keyser
- Department of Neurology, Center for Neurosciences, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium.,Department of Neurology, University Medical Center Groningen, Groningen, The Netherlands
| | - Sonia Van Dooren
- Center for Medical Genetics, Reproduction and Genetics; Genetics and Regenerative Medicine, UZ Brussel, Vrije Universiteit Brussel (VUB), Brussels, Belgium
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León Ariza HH, Valenzuela Faccini N, Rojas Ortega AC, Botero Rosas DA. Nav1.5 cardiac sodium channels, regulation and clinical implications. REVISTA DE LA FACULTAD DE MEDICINA 2015. [DOI: 10.15446/revfacmed.v62n4.44015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
<p>Voltage-gated sodium channels constitute a group of membrane<br />proteins widely distributed thought the body. In the heart, there<br />are at least six different isoforms, being the Nav1.5 the most<br />abundant. The channel is composed of an α subunit that is formed<br />by four domains of six segments each, and four much smaller β<br />subunits that provide stability and integrate other channels into<br />the α subunit. The function of the Nav1.5 channel is modulated<br />by intracellular cytoskeleton proteins, extracellular proteins,<br />calcium concentration, free radicals, and medications, among<br />other things. The study of the channel and its alterations has<br />grown thanks to its association with pathogenic conditions such<br />as Long QT syndrome, Brugada syndrome, atrial fibrillation,<br />arrhythmogenic ventricular dysplasia and complications during<br />ischemic processes.</p>
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Koenig X, Hilber K. The anti-addiction drug ibogaine and the heart: a delicate relation. Molecules 2015; 20:2208-28. [PMID: 25642835 PMCID: PMC4382526 DOI: 10.3390/molecules20022208] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 11/11/2014] [Accepted: 11/26/2014] [Indexed: 12/13/2022] Open
Abstract
The plant indole alkaloid ibogaine has shown promising anti-addictive properties in animal studies. Ibogaine is also anti-addictive in humans as the drug alleviates drug craving and impedes relapse of drug use. Although not licensed as therapeutic drug and despite safety concerns, ibogaine is currently used as an anti-addiction medication in alternative medicine in dozens of clinics worldwide. In recent years, alarming reports of life-threatening complications and sudden death cases, temporally associated with the administration of ibogaine, have been accumulating. These adverse reactions were hypothesised to be associated with ibogaine’s propensity to induce cardiac arrhythmias. The aim of this review is to recapitulate the current knowledge about ibogaine’s effects on the heart and the cardiovascular system, and to assess the cardiac risks associated with the use of this drug in anti- addiction therapy. The actions of 18-methoxycoronaridine (18-MC), a less toxic ibogaine congener with anti-addictive properties, are also considered.
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Affiliation(s)
- Xaver Koenig
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, Vienna 1090, Austria.
| | - Karlheinz Hilber
- Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstrasse 17, Vienna 1090, Austria.
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Kirchhof P, Tal T, Fabritz L, Klimas J, Nesher N, Schulte JS, Ehling P, Kanyshkova T, Budde T, Nikol S, Fortmueller L, Stallmeyer B, Müller FU, Schulze-Bahr E, Schmitz W, Zlotkin E, Kirchhefer U. First report on an inotropic peptide activating tetrodotoxin-sensitive, "neuronal" sodium currents in the heart. Circ Heart Fail 2014; 8:79-88. [PMID: 25424392 DOI: 10.1161/circheartfailure.113.001066] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND New therapeutic approaches to improve cardiac contractility without severe risk would improve the management of acute heart failure. Increasing systolic sodium influx can increase cardiac contractility, but most sodium channel activators have proarrhythmic effects that limit their clinical use. Here, we report the cardiac effects of a novel positive inotropic peptide isolated from the toxin of the Black Judean scorpion that activates neuronal tetrodotoxin-sensitive sodium channels. METHODS AND RESULTS All venoms and peptides were isolated from Black Judean Scorpions (Buthotus Hottentotta) caught in the Judean Desert. The full scorpion venom increased left ventricular function in sedated mice in vivo, prolonged ventricular repolarization, and provoked ventricular arrhythmias. An inotropic peptide (BjIP) isolated from the full venom by chromatography increased cardiac contractility but did neither provoke ventricular arrhythmias nor prolong cardiac repolarization. BjIP increased intracellular calcium in ventricular cardiomyocytes and prolonged inactivation of the cardiac sodium current. Low concentrations of tetrodotoxin (200 nmol/L) abolished the effect of BjIP on calcium transients and sodium current. BjIP did not alter the function of Nav1.5, but selectively activated the brain-type sodium channels Nav1.6 or Nav1.3 in cellular electrophysiological recordings obtained from rodent thalamic slices. Nav1.3 (SCN3A) mRNA was detected in human and mouse heart tissue. CONCLUSIONS Our pilot experiments suggest that selective activation of tetrodotoxin-sensitive neuronal sodium channels can safely increase cardiac contractility. As such, the peptide described here may become a lead compound for a new class of positive inotropic agents.
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Affiliation(s)
- Paulus Kirchhof
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.).
| | - Tzachy Tal
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Larissa Fabritz
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Jan Klimas
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Nir Nesher
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Jan S Schulte
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Petra Ehling
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Tatayana Kanyshkova
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Thomas Budde
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Sigrid Nikol
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Lisa Fortmueller
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Birgit Stallmeyer
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Frank U Müller
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Eric Schulze-Bahr
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Wilhelm Schmitz
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Eliahu Zlotkin
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
| | - Uwe Kirchhefer
- From the Department of Cardiovascular Medicine (P.K., L.F., S.N., L.F.), Department of Pharmacology and Toxicology (J.K., J.S.S., F.U.M., W.S., U.K.), and Department of Cardiovascular Medicine, Institute for Genetics of Heart Disease (IfGH) (B.S., E.S.-B.), Hospital of the University of Muenster, Muenster, Germany; Center for Cardiovascular Sciences, School of Clinical and Experimental Medicine, and SWBH NHS Trust, University of Birmingham, Birmingham, United Kingdom (P.K., L.F.); Technion Israel Institute of Technology, Haifa, Israel (T.T.); Department of Animal and Cell Biology, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel (T.T., N.N., E.Z.); Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University in Bratislava, Bratislava, Slovak Republic (J.K.); Department of Neurology, and Division of Neuropathophysiology, Institute of Physiology I (P.E.) and Institute of Physiology I (T.K., T.B.), University of Muenster, Muenster, Germany; and Department of Clinical and Interventional Angiology, Asklepios Clinic St. Georg, Hamburg, Germany (S.N.)
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Schmitt N, Grunnet M, Olesen SP. Cardiac potassium channel subtypes: new roles in repolarization and arrhythmia. Physiol Rev 2014; 94:609-53. [PMID: 24692356 DOI: 10.1152/physrev.00022.2013] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
About 10 distinct potassium channels in the heart are involved in shaping the action potential. Some of the K+ channels are primarily responsible for early repolarization, whereas others drive late repolarization and still others are open throughout the cardiac cycle. Three main K+ channels drive the late repolarization of the ventricle with some redundancy, and in atria this repolarization reserve is supplemented by the fairly atrial-specific KV1.5, Kir3, KCa, and K2P channels. The role of the latter two subtypes in atria is currently being clarified, and several findings indicate that they could constitute targets for new pharmacological treatment of atrial fibrillation. The interplay between the different K+ channel subtypes in both atria and ventricle is dynamic, and a significant up- and downregulation occurs in disease states such as atrial fibrillation or heart failure. The underlying posttranscriptional and posttranslational remodeling of the individual K+ channels changes their activity and significance relative to each other, and they must be viewed together to understand their role in keeping a stable heart rhythm, also under menacing conditions like attacks of reentry arrhythmia.
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Calhoun JD, Isom LL. The role of non-pore-forming β subunits in physiology and pathophysiology of voltage-gated sodium channels. Handb Exp Pharmacol 2014; 221:51-89. [PMID: 24737232 DOI: 10.1007/978-3-642-41588-3_4] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Voltage-gated sodium channel β1 and β2 subunits were discovered as auxiliary proteins that co-purify with pore-forming α subunits in brain. The other family members, β1B, β3, and β4, were identified by homology and shown to modulate sodium current in heterologous systems. Work over the past 2 decades, however, has provided strong evidence that these proteins are not simply ancillary ion channel subunits, but are multifunctional signaling proteins in their own right, playing both conducting (channel modulatory) and nonconducting roles in cell signaling. Here, we discuss evidence that sodium channel β subunits not only regulate sodium channel function and localization but also modulate voltage-gated potassium channels. In their nonconducting roles, VGSC β subunits function as immunoglobulin superfamily cell adhesion molecules that modulate brain development by influencing cell proliferation and migration, axon outgrowth, axonal fasciculation, and neuronal pathfinding. Mutations in genes encoding β subunits are linked to paroxysmal diseases including epilepsy, cardiac arrhythmia, and sudden infant death syndrome. Finally, β subunits may be targets for the future development of novel therapeutics.
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Affiliation(s)
- Jeffrey D Calhoun
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, 48109-5632, USA
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45
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Altered cardiac electrophysiology and SUDEP in a model of Dravet syndrome. PLoS One 2013; 8:e77843. [PMID: 24155976 PMCID: PMC3796479 DOI: 10.1371/journal.pone.0077843] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Accepted: 09/04/2013] [Indexed: 12/04/2022] Open
Abstract
Objective Dravet syndrome is a severe form of intractable pediatric epilepsy with a high incidence of SUDEP: Sudden Unexpected Death in epilepsy. Cardiac arrhythmias are a proposed cause for some cases of SUDEP, yet the susceptibility and potential mechanism of arrhythmogenesis in Dravet syndrome remain unknown. The majority of Dravet syndrome patients have denovo mutations in SCN1A, resulting in haploinsufficiency. We propose that, in addition to neuronal hyperexcitability, SCN1A haploinsufficiency alters cardiac electrical function and produces arrhythmias, providing a potential mechanism for SUDEP. Methods Postnatal day 15-21 heterozygous SCN1A-R1407X knock-in mice, expressing a human Dravet syndrome mutation, were used to investigate a possible cardiac phenotype. A combination of single cell electrophysiology and invivo electrocardiogram (ECG) recordings were performed. Results We observed a 2-fold increase in both transient and persistent Na+ current density in isolated Dravet syndrome ventricular myocytes that resulted from increased activity of a tetrodotoxin-resistant Na+ current, likely Nav1.5. Dravet syndrome myocytes exhibited increased excitability, action potential duration prolongation, and triggered activity. Continuous radiotelemetric ECG recordings showed QT prolongation, ventricular ectopic foci, idioventricular rhythms, beat-to-beat variability, ventricular fibrillation, and focal bradycardia. Spontaneous deaths were recorded in 2 DS mice, and a third became moribund and required euthanasia. Interpretation These data from single cell and whole animal experiments suggest that altered cardiac electrical function in Dravet syndrome may contribute to the susceptibility for arrhythmogenesis and SUDEP. These mechanistic insights may lead to critical risk assessment and intervention in human patients.
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Westenbroek RE, Bischoff S, Fu Y, Maier SKG, Catterall WA, Scheuer T. Localization of sodium channel subtypes in mouse ventricular myocytes using quantitative immunocytochemistry. J Mol Cell Cardiol 2013; 64:69-78. [PMID: 23982034 DOI: 10.1016/j.yjmcc.2013.08.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 07/22/2013] [Accepted: 08/15/2013] [Indexed: 01/16/2023]
Abstract
Voltage-gated sodium channels are responsible for the rising phase of the action potential in cardiac muscle. Previously, both TTX-sensitive neuronal sodium channels (NaV1.1, NaV1.2, NaV1.3, NaV1.4 and NaV1.6) and the TTX-resistant cardiac sodium channel (NaV1.5) have been detected in cardiac myocytes, but relative levels of protein expression of the isoforms were not determined. Using a quantitative approach, we analyzed z-series of confocal microscopy images from individual mouse myocytes stained with either anti-NaV1.1, anti-NaV1.2, anti-NaV1.3, anti-NaV1.4, anti-NaV1.5, or anti-NaV1.6 antibodies and calculated the relative intensity of staining for these sodium channel isoforms. Our results indicate that the TTX-sensitive channels represented approximately 23% of the total channels, whereas the TTX-resistant NaV1.5 channel represented 77% of the total channel staining in mouse ventricular myocytes. These ratios are consistent with previous electrophysiological studies in mouse ventricular myocytes. NaV1.5 was located at the cell surface, with high density at the intercalated disc, but was absent from the transverse (t)-tubular system, suggesting that these channels support surface conduction and inter-myocyte transmission. Low-level cell surface staining of NaV1.4 and NaV1.6 channels suggest a minor role in surface excitation and conduction. Conversely, NaV1.1 and NaV1.3 channels are localized to the t-tubules and are likely to support t-tubular transmission of the action potential to the myocyte interior. This quantitative immunocytochemical approach for assessing sodium channel density and localization provides a more precise view of the relative importance and possible roles of these individual sodium channel protein isoforms in mouse ventricular myocytes and may be applicable to other species and cardiac tissue types.
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Affiliation(s)
- Ruth E Westenbroek
- Department of Pharmacology, University of Washington, Seattle, WA 98195-7280, USA.
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