1
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Weinberg SH. Sodium channel subpopulations with distinct biophysical properties and subcellular localization enhance cardiac conduction. J Gen Physiol 2023; 155:e202313382. [PMID: 37285024 PMCID: PMC10250552 DOI: 10.1085/jgp.202313382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2023] [Revised: 05/02/2023] [Accepted: 05/24/2023] [Indexed: 06/08/2023] Open
Abstract
Sodium (Na+) current is responsible for the rapid depolarization of cardiac myocytes that triggers the cardiac action potential upstroke. Recent studies have illustrated the presence of multiple pools of Na+ channels with distinct biophysical properties and subcellular localization, including clustering of channels at the intercalated disk and along the lateral membrane. Computational studies predict that Na+ channel clusters at the intercalated disk can regulate cardiac conduction via modulation of the narrow intercellular cleft between electrically coupled myocytes. However, these studies have primarily focused on the redistribution of Na+ channels between intercalated disk and lateral membranes and have not considered the distinct biophysical properties of the Na+ channel subpopulations. In this study, we use computational modeling to simulate computational models of single cardiac cells and one-dimensional cardiac tissues and predict the function of distinct Na+ channel subpopulations. Single-cell simulations predict that a subpopulation of Na+ channels with shifted steady-state activation and inactivation voltage dependency promotes an earlier action potential upstroke. In cardiac tissues that account for distinct subcellular spatial localization, simulations predict that shifted Na+ channels contribute to faster and more robust conduction in response to changes in tissue structure (i.e., cleft width), gap junctional coupling, and rapid pacing rates. Simulations predict that the intercalated disk-localized shifted Na+ channels contribute proportionally more to total Na+ charge than lateral membrane-localized Na+ channels. Importantly, our work supports the hypothesis that Na+ channel redistribution may be a critical mechanism by which cells can respond to perturbations to support fast and robust conduction.
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Affiliation(s)
- Seth H. Weinberg
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
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2
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Yu C, Deng XJ, Xu D. Gene mutations in comorbidity of epilepsy and arrhythmia. J Neurol 2023; 270:1229-1248. [PMID: 36376730 DOI: 10.1007/s00415-022-11430-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 10/14/2022] [Accepted: 10/15/2022] [Indexed: 11/16/2022]
Abstract
Epilepsy is one of the most common neurological disorders, and sudden unexpected death in epilepsy (SUDEP) is the most severe outcome of refractory epilepsy. Arrhythmia is one of the heterogeneous factors in the pathophysiological mechanism of SUDEP with a high incidence in patients with refractory epilepsy, increasing the risk of premature death. The gene co-expressed in the brain and heart is supposed to be the genetic basis between epilepsy and arrhythmia, among which the gene encoding ion channel contributes to the prevalence of "cardiocerebral channelopathy" theory. Nevertheless, this theory could only explain the molecular mechanism of comorbid arrhythmia in part of patients with epilepsy (PWE). Therefore, we summarized the mutant genes that can induce comorbidity of epilepsy and arrhythmia and the possible corresponding treatments. These variants involved the genes encoding sodium, potassium, calcium and HCN channels, as well as some non-ion channel coding genes such as CHD4, PKP2, FHF1, GNB5, and mitochondrial genes. The relationship between genotype and clinical phenotype was not simple linear. Indeed, genes co-expressed in the brain and heart could independently induce epilepsy and/or arrhythmia. Mutant genes in brain could affect cardiac rhythm through central or peripheral regulation, while in the heart it could also affect cerebral electrical activity by changing the hemodynamics or internal environment. Analysis of mutations in comorbidity of epilepsy and arrhythmia could refine and expand the theory of "cardiocerebral channelopathy" and provide new insights for risk stratification of premature death and corresponding precision therapy in PWE.
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Affiliation(s)
- Cheng Yu
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, 430022, Hubei Province, China
| | - Xue-Jun Deng
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, 430022, Hubei Province, China
| | - Da Xu
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, 430022, Hubei Province, China.
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3
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Fouda MA, Mohamed YF, Fernandez R, Ruben PC. Anti-inflammatory effects of cannabidiol against lipopolysaccharides in cardiac sodium channels. Br J Pharmacol 2022; 179:5259-5272. [PMID: 35906756 DOI: 10.1111/bph.15936] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 07/13/2022] [Accepted: 07/24/2022] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND Sepsis, caused by a dysregulated host response to infections, can lead to cardiac arrhythmias. However, the mechanisms underlying sepsis-induced inflammation, and how inflammation provokes cardiac arrhythmias, are not well understood. We hypothesized that CBD may ameliorate lipopolysaccharides (LPS)-induced cardiotoxicity via Toll-like receptor 4 (TLR-4) and cardiac sodium channels (Nav1.5). METHODS AND RESULTS We incubated human immune cells (THP-1 macrophages) with LPS for 24 hours, then extracted the THP-1 incubation media. ELISA assay showed that LPS (1 or 5 μg/ml), in a concentration-dependent manner, or MPLA (TLR-4 agonist, 5 μg/ml) stimulated the THP-1 cells to release inflammatory cytokines (TNF-α and IL-6). Prior incubation (4 hours) with cannabidiol (CBD: 5 μM) or C34 (TLR-4 antagonist: 5 μg/ml) inhibited LPS and MPLA-induced release of both IL-6 and TNF-α. Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) were subsequently incubated for 24 hours in the media extracted from THP-1 cells incubated with LPS, MPLA alone, or in combination with CBD or C34. Voltage-clamp experiments showed a right shift in the voltage dependence of Nav1.5 activation, steady state fast inactivation (SSFI), increased persistent current and prolonged in silico action potential duration in hiSPC-CM incubated in the LPS or MPLA-THP-1 media. Co-incubation with CBD or C34 rescued the biophysical dysfunction caused by LPS and MPLA. CONCLUSION Our results suggest that CBD may protect against sepsis-induced inflammation and subsequent arrhythmias through (i) inhibition of the release of inflammatory cytokines, antioxidant and anti-apoptotic effects and/or (ii) direct effect on Nav1.5.
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Affiliation(s)
- Mohamed A Fouda
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada.,Department of Pharmacology and Toxicology, Alexandria University, Alexandria, Egypt
| | - Yasmine Fathy Mohamed
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada.,Department of Microbiology and Immunology, Alexandria University, Alexandria, Egypt
| | - Rachel Fernandez
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
| | - Peter C Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
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4
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Allam C. Acoustic energy and cardiac electrophysiology: Ultrasonic cardiac pacing and novel shockwave ablation catheters. Pacing Clin Electrophysiol 2022; 45:800-806. [DOI: 10.1111/pace.14513] [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: 02/09/2022] [Revised: 04/11/2022] [Accepted: 04/22/2022] [Indexed: 11/30/2022]
Affiliation(s)
- Chadi Allam
- Faculty of Medicine Saint‐Joseph University Beirut Lebanon
- Department of Cardiology Hôtel‐Dieu de France Hospital Beirut Lebanon
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5
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Fouda MA, Ghovanloo MR, Ruben PC. Late sodium current: incomplete inactivation triggers seizures, myotonias, arrhythmias, and pain syndromes. J Physiol 2022; 600:2835-2851. [PMID: 35436004 DOI: 10.1113/jp282768] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 04/12/2022] [Indexed: 11/08/2022] Open
Abstract
Acquired and inherited dysfunction in voltage-gated sodium channels underlies a wide range of diseases. "In addition to the defects in trafficking and expression, sodium channelopathies are also caused by dysfunction in one or several gating properties, for instance activation or inactivation. Disruption of the channel inactivation leads to the increased late sodium current, which is a common defect in seizure disorders, cardiac arrhythmias skeletal muscle myotonia and pain. An increase in late sodium current leads to repetitive action potential in neurons and skeletal muscles, and prolonged action potential duration in the heart. In this topical review, we compare the effects of late sodium current in brain, heart, skeletal muscle, and peripheral nerves. Abstract figure legend Shows cartoon illustration of general Nav channel transitions between (1) resting, (2) open, and (3) fast inactivated states. Disruption of the inactivation process exacerbates (4) late sodium currents. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Mohamed A Fouda
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada.,Department of Pharmacology and Toxicology, Alexandria University, Alexandria, Egypt
| | | | - Peter C Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
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6
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Absolute Quantification of Nav1.5 Expression by Targeted Mass Spectrometry. Int J Mol Sci 2022; 23:ijms23084177. [PMID: 35456996 PMCID: PMC9028338 DOI: 10.3390/ijms23084177] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/07/2022] [Accepted: 04/08/2022] [Indexed: 11/20/2022] Open
Abstract
Nav1.5 is the pore forming α-subunit of the cardiac voltage-gated sodium channel that initiates cardiac action potential and regulates the human heartbeat. A normal level of Nav1.5 is crucial to cardiac function and health. Over- or under-expression of Nav1.5 can cause various cardiac diseases ranging from short PR intervals to Brugada syndromes. An assay that can directly quantify the protein amount in biological samples would be a priori to accurately diagnose and treat Nav1.5-associated cardiac diseases. Due to its large size (>200 KD), multipass transmembrane domains (24 transmembrane passes), and heavy modifications, Nav1.5 poses special quantitation challenges. To date, only the relative quantities of this protein have been measured in biological samples. Here, we describe the first targeted and mass spectrometry (MS)-based quantitative assay that can provide the copy numbers of Nav1.5 in cells with a well-defined lower limit of quantification (LLOQ) and precision. Applying the developed assay, we successfully quantified transiently expressed Nav1.5 in as few as 1.5 million Chinese hamster ovary (CHO) cells. The obtained quantity was 3 ± 2 fmol on the column and 3 ± 2 × 104 copies/cell. To our knowledge, this is the first absolute quantity of Nav1.5 measured in a biological sample.
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7
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Horváth B, Szentandrássy N, Almássy J, Dienes C, Kovács ZM, Nánási PP, Banyasz T. Late Sodium Current of the Heart: Where Do We Stand and Where Are We Going? Pharmaceuticals (Basel) 2022; 15:ph15020231. [PMID: 35215342 PMCID: PMC8879921 DOI: 10.3390/ph15020231] [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: 01/13/2022] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 02/05/2023] Open
Abstract
Late sodium current has long been linked to dysrhythmia and contractile malfunction in the heart. Despite the increasing body of accumulating information on the subject, our understanding of its role in normal or pathologic states is not complete. Even though the role of late sodium current in shaping action potential under physiologic circumstances is debated, it’s unquestioned role in arrhythmogenesis keeps it in the focus of research. Transgenic mouse models and isoform-specific pharmacological tools have proved useful in understanding the mechanism of late sodium current in health and disease. This review will outline the mechanism and function of cardiac late sodium current with special focus on the recent advances of the area.
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Affiliation(s)
- Balázs Horváth
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
| | - Norbert Szentandrássy
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
- Department of Basic Medical Sciences, Faculty of Dentistry, University of Debrecen, 4032 Debrecen, Hungary
| | - János Almássy
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
| | - Csaba Dienes
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
| | - Zsigmond Máté Kovács
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
| | - Péter P. Nánási
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
- Department of Dental Physiology and Pharmacology, University of Debrecen, 4032 Debrecen, Hungary
| | - Tamas Banyasz
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary; (B.H.); (N.S.); (J.A.); (C.D.); (Z.M.K.); (P.P.N.)
- Correspondence: ; Tel.: +36-(52)-255-575; Fax: +36-(52)-255-116
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8
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Wu X, Hoeker GS, Blair GA, King DR, Gourdie RG, Weinberg SH, Poelzing S. Hypernatremia and intercalated disc edema synergistically exacerbate long-QT syndrome type 3 phenotype. Am J Physiol Heart Circ Physiol 2021; 321:H1042-H1055. [PMID: 34623182 DOI: 10.1152/ajpheart.00366.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cardiac voltage-gated sodium channel gain-of-function prolongs repolarization in the long-QT syndrome type 3 (LQT3). Previous studies suggest that narrowing the perinexus within the intercalated disc, leading to rapid sodium depletion, attenuates LQT3-associated action potential duration (APD) prolongation. However, it remains unknown whether extracellular sodium concentration modulates APD prolongation during sodium channel gain-of-function. We hypothesized that elevated extracellular sodium concentration and widened perinexus synergistically prolong APD in LQT3. LQT3 was induced with sea anemone toxin (ATXII) in Langendorff-perfused guinea pig hearts (n = 34). Sodium concentration was increased from 145 to 160 mM. Perinexal expansion was induced with mannitol or the sodium channel β1-subunit adhesion domain antagonist (βadp1). Epicardial ventricular action potentials were optically mapped. Individual and combined effects of varying clefts and sodium concentrations were simulated in a computational model. With ATXII, both mannitol and βadp1 significantly widened the perinexus and prolonged APD, respectively. The elevated sodium concentration alone significantly prolonged APD as well. Importantly, the combination of elevated sodium concentration and perinexal widening synergistically prolonged APD. Computational modeling results were consistent with animal experiments. Concurrently elevating extracellular sodium and increasing intercalated disc edema prolongs repolarization more than the individual interventions alone in LQT3. This synergistic effect suggests an important clinical implication that hypernatremia in the presence of cardiac edema can markedly increase LQT3-associated APD prolongation. Therefore, to our knowledge, this is the first study to provide evidence of a tractable and effective strategy to mitigate LQT3 phenotype by means of managing sodium levels and preventing cardiac edema in patients.NEW & NOTEWORTHY This is the first study to demonstrate that the long-QT syndrome type 3 (LQT3) phenotype can be exacerbated or concealed by regulating extracellular sodium concentrations and/or the intercalated disc separation. The animal experiments and computational modeling in the current study reveal a critically important clinical implication: sodium dysregulation in the presence of edema within the intercalated disc can markedly increase the risk of arrhythmia in LQT3. These findings strongly suggest that maintaining extracellular sodium within normal physiological limits may be an effective and inexpensive therapeutic option for patients with congenital or acquired sodium channel gain-of-function diseases.
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Affiliation(s)
- Xiaobo Wu
- Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University, Roanoke, Virginia.,Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia
| | - Gregory S Hoeker
- Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia
| | - Grace A Blair
- Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University, Roanoke, Virginia.,Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia
| | - D Ryan King
- Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University, Roanoke, Virginia.,Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia
| | - Robert G Gourdie
- Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia.,Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
| | - Seth H Weinberg
- Department of Biomedical Engineering, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio
| | - Steven Poelzing
- Translational Biology, Medicine, and Health Graduate Program, Virginia Polytechnic Institute and State University, Roanoke, Virginia.,Center for Heart and Reparative Medicine Research, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, Virginia.,Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia
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9
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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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10
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IL-33 Is Involved in the Anti-Inflammatory Effects of Butyrate and Propionate on TNFα-Activated Endothelial Cells. Int J Mol Sci 2021; 22:ijms22052447. [PMID: 33671042 PMCID: PMC7957702 DOI: 10.3390/ijms22052447] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/23/2021] [Accepted: 02/24/2021] [Indexed: 12/21/2022] Open
Abstract
Short-chain fatty acids (e.g., butyrate and propionate) are able to diminish endothelial cell activation. The aim of this study was to investigate whether intracellular IL-33 mediates the effects of butyrate and propionate on TNFα-induced IL-8 production and vascular cell adhesion molecule-1 (VCAM-1) expression. In addition, it was investigated whether regulating NF-κB and MAPK signaling pathways are involved. Intracellular IL-33 was measured in human endothelial cells (HUVECs) pre-incubated for 24 h with butyrate (0.1 mM or 5 mM), propionate (0.3 mM or 10 mM), or trichostatin A (TSA, 0.5 μM) prior to TNFα (1 ng/mL) stimulation (24 h). The effects of butyrate, propionate, and TSA on TNFα-induced IL-8, vascular cell adhesion molecule-1 (VCAM-1), NF-κB, and MAPK signaling pathways in normal HUVECs and IL-33 siRNA (siIL-33)-transfected HUVECs were compared to study the role of IL-33 in the protective effects of butyrate and propionate. Endogenous IL-33 was highly expressed in the perinuclear in HUVECs, which was significantly reduced by TNFα stimulation. The TNFα-induced reduction in IL-33 was prevented by pre-incubation with butyrate or propionate. Butyrate (0.1 mM), propionate (0.3 mM), and TSA inhibited the IL-8 production and activation of NF-κB. Interestingly, this effect was not observed in siIL-33-transfected HUVECs. The effects of butyrate (5 mM), propionate (10 mM), and TSA (0.5 μM) on VCAM-1 expression and activation of MAPK signaling pathways were not affected by siIL-33 transfection. In conclusion, we showed that the inhibitory effects of butyrate and propionate on TNFα-induced IL-8 production were mediated by the HDACs/IL-33/NF-κB pathway, while their effects on VCAM-1 expression might be associated with the HDACs/MAPK signaling pathway, independently of IL-33.
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11
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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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12
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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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13
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Vermij SH, Abriel H, Kucera JP. Modeling Depolarization Delay, Sodium Currents, and Electrical Potentials in Cardiac Transverse Tubules. Front Physiol 2020; 10:1487. [PMID: 31920695 PMCID: PMC6916517 DOI: 10.3389/fphys.2019.01487] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 11/21/2019] [Indexed: 01/22/2023] Open
Abstract
T-tubules are invaginations of the lateral membrane of striated muscle cells that provide a large surface for ion channels and signaling proteins, thereby supporting excitation–contraction coupling. T-tubules are often remodeled in heart failure. To better understand the electrical behavior of T-tubules of cardiac cells in health and disease, this study addresses two largely unanswered questions regarding their electrical properties: (1) the delay of T-tubular membrane depolarization and (2) the effects of T-tubular sodium current on T-tubular potentials. Here, we present an elementary computational model to determine the delay in depolarization of deep T-tubular membrane segments as the narrow T-tubular lumen provides resistance against the extracellular current. We compare healthy tubules to tubules with constrictions and diseased tubules from mouse and human, and conclude that constrictions greatly delay T-tubular depolarization, while diseased T-tubules depolarize faster than healthy ones due to tubule widening. Increasing the tubule length non-linearly delays the depolarization. We moreover model the effect of T-tubular sodium current on intraluminal T-tubular potentials. We observe that extracellular potentials become negative during the sodium current transient (up to −40 mV in constricted T-tubules), which feedbacks on sodium channel function (self-attenuation) in a manner resembling ephaptic effects that have been described for intercalated discs where opposing membranes are very close together. The intraluminal potential and sodium current self-attenuation however greatly depend on sodium current conductance. These results show that (1) the changes in passive electrical properties of remodeled T-tubules cannot explain the excitation–contraction coupling defects in diseased cells; and (2) the sodium current may modulate intraluminal potentials. Such extracellular potentials might also affect excitation–contraction coupling and macroscopic conduction.
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Affiliation(s)
- Sarah Helena Vermij
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Hugues Abriel
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
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14
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A fundamental evaluation of the electrical properties and function of cardiac transverse tubules. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2019; 1867:118502. [PMID: 31269418 DOI: 10.1016/j.bbamcr.2019.06.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 06/07/2019] [Accepted: 06/28/2019] [Indexed: 11/20/2022]
Abstract
This work discusses active and passive electrical properties of transverse (T-)tubules in ventricular cardiomyocytes to understand the physiological roles of T-tubules. T-tubules are invaginations of the lateral membrane that provide a large surface for calcium-handling proteins to facilitate sarcomere shortening. Higher heart rates correlate with higher T-tubular densities in mammalian ventricular cardiomyocytes. We assess ion dynamics in T-tubules and the effects of sodium current in T-tubules on the extracellular potential, which leads to a partial reduction of the sodium current in deep segments of a T-tubule. We moreover reflect on the impact of T-tubules on macroscopic conduction velocity, integrating fundamental principles of action potential propagation and conduction. We also theoretically assess how the conduction velocity is affected by different T-tubular sodium current densities. Lastly, we critically assess literature on ion channel expression to determine whether action potentials can be initiated in T-tubules.
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15
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Rougier JS, Essers MC, Gillet L, Guichard S, Sonntag S, Shmerling D, Abriel H. A Distinct Pool of Na v1.5 Channels at the Lateral Membrane of Murine Ventricular Cardiomyocytes. Front Physiol 2019; 10:834. [PMID: 31333492 PMCID: PMC6619393 DOI: 10.3389/fphys.2019.00834] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 06/17/2019] [Indexed: 01/22/2023] Open
Abstract
Background: In cardiac ventricular muscle cells, the presence of voltage-gated sodium channels Nav1.5 at the lateral membrane depends in part on the interaction between the dystrophin–syntrophin complex and the Nav1.5 C-terminal PDZ-domain-binding sequence Ser-Ile-Val (SIV motif). α1-Syntrophin, a PDZ-domain adaptor protein, mediates the interaction between Nav1.5 and dystrophin at the lateral membrane of cardiac cells. Using the cell-attached patch-clamp approach on cardiomyocytes expressing Nav1.5 in which the SIV motif is deleted (ΔSIV), sodium current (INa) recordings from the lateral membrane revealed a SIV-motif-independent INa. Since immunostaining has suggested that Nav1.5 is expressed in transverse (T-) tubules, this remaining INa might be carried by channels in the T-tubules. Of note, a recent study using heterologous expression systems showed that α1-syntrophin also interacts with the Nav1.5 N-terminus, which may explain the SIV-motif independent INa at the lateral membrane of cardiomyocytes. Aim: To address the role of α1-syntrophin in regulating the INa at the lateral membrane of cardiac cells. Methods and Results: Patch-clamp experiments in cell-attached configuration were performed on the lateral membranes of wild-type, α1-syntrophin knockdown, and ΔSIV ventricular mouse cardiomyocytes. Compared to wild-type, a reduction of the lateral INa was observed in myocytes from α1-syntrophin knockdown hearts. Similar to ΔSIV myocytes, a remaining INa was still recorded. In addition, cell-attached INa recordings from lateral membrane did not differ significantly between non-detubulated and detubulated ΔSIV cardiomyocytes. Lastly, we obtained evidence suggesting that cell-attached patch-clamp experiments on the lateral membrane cannot record currents carried by channels in T-tubules such as calcium channels. Conclusion: Altogether, these results suggest the presence of a sub-pool of sodium channels at the lateral membrane of cardiomyocytes that is independent of α1-syntrophin and the PDZ-binding motif of Nav1.5, located in membrane domains outside of T-tubules. The question of a T-tubular pool of Nav1.5 channels, however, remains open.
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Affiliation(s)
| | - Maria C Essers
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Ludovic Gillet
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland.,Pain Center, Department of Anesthesiology, Lausanne University Hospital, Lausanne, Switzerland.,Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Sabrina Guichard
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | | | | | - Hugues Abriel
- Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
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16
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Wu M, Tran PN, Sheng J, Randolph AL, Wu WW. Drug potency on inhibiting late Na + current is sensitive to gating modifier and current region where drug effects were measured. J Pharmacol Toxicol Methods 2019; 100:106605. [PMID: 31255744 DOI: 10.1016/j.vascn.2019.106605] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 06/18/2019] [Accepted: 06/24/2019] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Cardiac late Na+ current (INaL) contributes to ventricular action potential duration. Pathological increase in INaL is arrhythmogenic, and inhibition of INaL offers protection against ventricular repolarization disturbance. Recently, two INaL datasets generated by different laboratories that assessed current inhibition by a panel of clinical drugs as a part of the Comprehensive in vitro Proarrhythmia Assay (CiPA) initiative were published. The results revealed a surprising degree of data variability despite of the use of a standardized voltage protocol. This study investigated whether remaining procedural differences related to experimental methods and data analysis associated with these datasets can produce differences in INaL pharmacology. METHODS Whole cell voltage clamp recordings were performed on cells expressing NaV1.5 α- and β1-subunits to study: 1) the impact of gating modifiers used to augment INaL (ATX-II vs. veratridine), internal solution composition (with vs. without ATP and GTP), and recording temperature (23 °C vs 37 °C) on stability of INaL measured across the duration of a patch clamp experiment; 2) mechanisms of each gating modifier on Na+ channels; and 3) effects of six drugs (lidocaine, mexiletine, chloroquine, ranolazine, ritonavir, and verapamil) on INaL induced by either gating modifier. RESULTS Stability of INaL is affected by the choice of gating modifier, presence of nucleotides in the internal solution, and recording temperature. ATX-II and veratridine produced different changes in Na+ channel gating, inducing mechanistically distinct INaL. Drug potencies on inhibiting INaL were dependent on the choice of gating modifier and current region where drug effects were measured. DISCUSSION INaL pharmacology can be impacted by all experimental factors examined in this study. The effect of gating modifier and current region used to quantify drug inhibition alone led to 30× difference in half inhibitory concentration (IC50) for ritonavir, demonstrating that substantial difference in drug inhibition can be produced. Drug potencies on inhibiting INaL derived from different patch clamp studies may thus not be generalizable. For INaL pharmacology to be useful for in silico modeling or interpreting drug-induced changes in cardiac action potentials or ECG, standardizing INaL experimental procedures including data analysis methods is necessary to minimize data variability.
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Affiliation(s)
- Min Wu
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Center for Drug Evaluation and Research, The US Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States of America
| | - Phu N Tran
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Center for Drug Evaluation and Research, The US Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States of America
| | - Jiansong Sheng
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Center for Drug Evaluation and Research, The US Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States of America
| | - Aaron L Randolph
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Center for Drug Evaluation and Research, The US Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States of America
| | - Wendy W Wu
- Division of Applied Regulatory Science, Office of Clinical Pharmacology, Center for Drug Evaluation and Research, The US Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, United States of America.
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17
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Jæger KH, Edwards AG, McCulloch A, Tveito A. Properties of cardiac conduction in a cell-based computational model. PLoS Comput Biol 2019; 15:e1007042. [PMID: 31150383 PMCID: PMC6561587 DOI: 10.1371/journal.pcbi.1007042] [Citation(s) in RCA: 32] [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: 11/24/2018] [Revised: 06/12/2019] [Accepted: 04/23/2019] [Indexed: 11/18/2022] Open
Abstract
The conduction of electrical signals through cardiac tissue is essential for maintaining the function of the heart, and conduction abnormalities are known to potentially lead to life-threatening arrhythmias. The properties of cardiac conduction have therefore been the topic of intense study for decades, but a number of questions related to the mechanisms of conduction still remain unresolved. In this paper, we demonstrate how the so-called EMI model may be used to study some of these open questions. In the EMI model, the extracellular space, the cell membrane, the intracellular space and the cell connections are all represented as separate parts of the computational domain, and the model therefore allows for study of local properties that are hard to represent in the classical homogenized bidomain or monodomain models commonly used to study cardiac conduction. We conclude that a non-uniform sodium channel distribution increases the conduction velocity and decreases the time delays over gap junctions of reduced coupling in the EMI model simulations. We also present a theoretical optimal cell length with respect to conduction velocity and consider the possibility of ephaptic coupling (i.e. cell-to-cell coupling through the extracellular potential) acting as an alternative or supporting mechanism to gap junction coupling. We conclude that for a non-uniform distribution of sodium channels and a sufficiently small intercellular distance, ephaptic coupling can influence the dynamics of the sodium channels and potentially provide cell-to-cell coupling when the gap junction connection is absent. The electrochemical wave traversing the heart during every beat is essential for cardiac pumping function and supply of blood to the body. Understanding the stability of this wave is crucial to understanding how lethal arrhythmias are generated. Despite this importance, our knowledge of the physical determinants of wave propagation are still evolving. One particular challenge has been the lack of accurate mathematical models of conduction at the cellular level. Because cardiac muscle is an electrical syncytium, in which direct charge transfer between cells drives wave propagation, classical bidomain and monodomain tissue models employ a homogenized approximation of this process. This approximation is not valid at the length scale of single cells, and prevents any analysis of how cellular structures impact cardiac conduction. Instead, so-called microdomain models must be used for these questions. Here we utilize a recently developed modelling framework that is well suited to represent small collections of cells. By applying this framework, we show that concentration of sodium channels at the longitudinal borders of myocytes accelerates cardiac conduction. We also demonstrate that when juxtaposed cells are sufficiently close, this non-uniform distribution induces large ephaptic currents, which contribute to intercellular coupling.
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Affiliation(s)
| | | | - Andrew McCulloch
- Department of Bioengineering, University of California, San Diego, California, United States of America
| | - Aslak Tveito
- Simula Research Laboratory, Oslo, Norway
- * E-mail:
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18
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Johnson CN. Calcium modulation of cardiac sodium channels. J Physiol 2019; 598:2835-2846. [PMID: 30707447 DOI: 10.1113/jp277553] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2018] [Accepted: 01/08/2019] [Indexed: 12/28/2022] Open
Abstract
Modification of voltage-gated Na+ channel (NaV ) function by intracellular Ca2+ has been a topic of much controversy. Early studies relied on measuring NaV function in the absence or presence of intracellular Ca2+ , and generated seemingly disparate results. Subsequent investigations revealed the mechanism(s) of Ca2+ -driven NaV modulation are complex and involve multiple accessory proteins. The Ca2+ -sensing protein calmodulin (CaM) has a central role in tuning NaV function to [Ca2+ ]i , but the mechanism has been obscured by other proteins (such as fibroblast growth factors (FGF) or CaM-dependent kinase II (CaMKII)) that can also modify channel function or exert an influence in a Ca2+ -dependent manner. Significant progress has been made in understanding the architecture of full-length ion channels and the structural and biophysical details of NaV -accessory protein interactions. Interdisciplinary structure-function studies are beginning to resolve the effect each interaction has on NaV gating. Carefully designed structure-guided or strategically selected disease-associated mutations are able to impair NaV -accessory protein interactions without altering other properties of channel function. Recently CaM was found to engage part of NaV 1.5 that is required for channel inactivation with high affinity. Careful impairment of this interaction disrupted NaV 1.5's ability to recover from inactivation. Such results support a paradigm of CaM-facilitated recovery from inactivation (CFRI). How NaV -CaM, CaMKII and FGF/fibroblast growth factor homologous factor interactions affect the timing or function of CFRI in cardiomyocytes remain open questions that are discussed herein. Moreover whether CFRI dysfunction or premature activation underlie certain NaV channelopathies are important questions that will require further investigation.
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Affiliation(s)
- Christopher N Johnson
- The Ohio State Wexner Medical Centre, Dorothy M. Davis Heart & Lung Research Institute, Columbus, OH, USA.,Vanderbilt Centre for Arrhythmia Research and Therapeutics, Division of Clinical Pharmacology, Nashville, TN, USA
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19
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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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20
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Frasier CR, Zhang H, Offord J, Dang LT, Auerbach DS, Shi H, Chen C, Goldman AM, Eckhardt LL, Bezzerides VJ, Parent JM, Isom LL. Channelopathy as a SUDEP Biomarker in Dravet Syndrome Patient-Derived Cardiac Myocytes. Stem Cell Reports 2018; 11:626-634. [PMID: 30146492 PMCID: PMC6135724 DOI: 10.1016/j.stemcr.2018.07.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 07/23/2018] [Accepted: 07/26/2018] [Indexed: 12/31/2022] Open
Abstract
Dravet syndrome (DS) is a severe developmental and epileptic encephalopathy with a high incidence of sudden unexpected death in epilepsy (SUDEP). Most DS patients carry de novo variants in SCN1A, resulting in Nav1.1 haploinsufficiency. Because SCN1A is expressed in heart and in brain, we proposed that cardiac arrhythmia contributes to SUDEP in DS. We generated DS patient and control induced pluripotent stem cell-derived cardiac myocytes (iPSC-CMs). We observed increased sodium current (INa) and spontaneous contraction rates in DS patient iPSC-CMs versus controls. For the subject with the largest increase in INa, cardiac abnormalities were revealed upon clinical evaluation. Generation of a CRISPR gene-edited heterozygous SCN1A deletion in control iPSCs increased INa density in iPSC-CMs similar to that seen in patient cells. Thus, the high risk of SUDEP in DS may result from a predisposition to cardiac arrhythmias in addition to seizures, reflecting expression of SCN1A in heart and brain.
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Affiliation(s)
- Chad R Frasier
- Department of Pharmacology, University of Michigan Medical School, 2301E MSRB III, Ann Arbor, MI 48109, USA
| | - Helen Zhang
- Department of Neurology, University of Michigan Medical School, 5021 BSRB, Ann Arbor, MI 48109, USA
| | - James Offord
- Department of Pharmacology, University of Michigan Medical School, 2301E MSRB III, Ann Arbor, MI 48109, USA
| | - Louis T Dang
- Division of Pediatric Neurology, Department of Pediatrics and Communicable Diseases, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - David S Auerbach
- Department of Pharmacology, University of Michigan Medical School, 2301E MSRB III, Ann Arbor, MI 48109, USA
| | - Huilin Shi
- Department of Neurology, University of Michigan Medical School, 5021 BSRB, Ann Arbor, MI 48109, USA
| | - Chunling Chen
- Department of Pharmacology, University of Michigan Medical School, 2301E MSRB III, Ann Arbor, MI 48109, USA
| | - Alica M Goldman
- Ann Arbor VA Healthcare System, University of Michigan Medical School, Ann Arbor, MI 48109, USA; Department of Neurology, Baylor College of Medicine, Houston, TX 77030, USA
| | - L Lee Eckhardt
- Cellular and Molecular Arrhythmia Research Program, Division of Cardiovascular Medicine, University of Wisconsin, Madison, WI 53705, USA
| | - Vassilios J Bezzerides
- Cardiology, Electrophysiology Division, Boston Children's Hospital, Boston, MA 02115, USA
| | - Jack M Parent
- Department of Neurology, University of Michigan Medical School, 5021 BSRB, Ann Arbor, MI 48109, USA; Ann Arbor VA Healthcare System, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
| | - Lori L Isom
- Department of Pharmacology, University of Michigan Medical School, 2301E MSRB III, Ann Arbor, MI 48109, USA; Department of Neurology, University of Michigan Medical School, 5021 BSRB, Ann Arbor, MI 48109, USA.
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21
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Radwański PB, Johnson CN, Györke S, Veeraraghavan R. Cardiac Arrhythmias as Manifestations of Nanopathies: An Emerging View. Front Physiol 2018; 9:1228. [PMID: 30233404 PMCID: PMC6131669 DOI: 10.3389/fphys.2018.01228] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 08/14/2018] [Indexed: 12/21/2022] Open
Abstract
A nanodomain is a collection of proteins localized within a specialized, nanoscale structural environment, which can serve as the functional unit of macroscopic physiologic processes. We are beginning to recognize the key roles of cardiomyocyte nanodomains in essential processes of cardiac physiology such as electrical impulse propagation and excitation–contraction coupling (ECC). There is growing appreciation of nanodomain dysfunction, i.e., nanopathy, as a mechanistic driver of life-threatening arrhythmias in a variety of pathologies. Here, we offer an overview of current research on the role of nanodomains in cardiac physiology with particular emphasis on: (1) sodium channel-rich nanodomains within the intercalated disk that participate in cell-to-cell electrical coupling and (2) dyadic nanodomains located along transverse tubules that participate in ECC. The beat to beat function of cardiomyocytes involves three phases: the action potential, the calcium transient, and mechanical contraction/relaxation. In all these phases, cell-wide function results from the aggregation of the stochastic function of individual proteins. While it has long been known that proteins that exist in close proximity influence each other’s function, it is increasingly appreciated that there exist nanoscale structures that act as functional units of cardiac biophysical phenomena. Termed nanodomains, these structures are collections of proteins, localized within specialized nanoscale structural environments. The nano-environments enable the generation of localized electrical and/or chemical gradients, thereby conferring unique functional properties to these units. Thus, the function of a nanodomain is determined by its protein constituents as well as their local structural environment, adding an additional layer of complexity to cardiac biology and biophysics. However, with the emergence of experimental techniques that allow direct investigation of structure and function at the nanoscale, our understanding of cardiac physiology and pathophysiology at these scales is rapidly advancing. Here, we will discuss the structure and functions of multiple cardiomyocyte nanodomains, and novel strategies that target them for the treatment of cardiac arrhythmias.
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Affiliation(s)
- Przemysław B Radwański
- Bob and Corinne Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, United States.,Division of Pharmacy Practice and Science, College of Pharmacy, The Ohio State University, Columbus, OH, United States
| | - Christopher N Johnson
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Vanderbilt Center for Arrhythmia Research and Therapeutics, Nashville, TN, United States
| | - Sándor Györke
- Bob and Corinne Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, United States
| | - Rengasayee Veeraraghavan
- Bob and Corinne Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, United States.,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, United States.,Department of Biomedical Engineering, The Ohio State University, Columbus, OH, United States
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22
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Chevalier M, Vermij SH, Wyler K, Gillet L, Keller I, Abriel H. Transcriptomic analyses of murine ventricular cardiomyocytes. Sci Data 2018; 5:180170. [PMID: 30129933 PMCID: PMC6103258 DOI: 10.1038/sdata.2018.170] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 06/14/2018] [Indexed: 12/27/2022] Open
Abstract
Mice are used universally as model organisms for studying heart physiology, and a plethora of genetically modified mouse models exist to study cardiac disease. Transcriptomic data for whole-heart tissue are available, but not yet for isolated ventricular cardiomyocytes. Our lab therefore collected comprehensive RNA-seq data from wildtype murine ventricular cardiomyocytes as well as from knockout models of the ion channel regulators CASK, dystrophin, and SAP97. We also elucidate ion channel expression from wild-type cells to help forward the debate about which ion channels are expressed in cardiomyocytes. Researchers studying the heart, and especially cardiac arrhythmias, may benefit from these cardiomyocyte-specific transcriptomic data to assess expression of genes of interest.
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Affiliation(s)
- Morgan Chevalier
- Ion Channels and Channelopathies Laboratory, Institute for Biochemistry and Molecular Medicine, University of Bern, 3012 Bern, Switzerland
| | - Sarah H Vermij
- Ion Channels and Channelopathies Laboratory, Institute for Biochemistry and Molecular Medicine, University of Bern, 3012 Bern, Switzerland
| | - Kurt Wyler
- Interfaculty Bioinformatics Unit and Swiss Institute of Bioinformatics, University of Bern, 3012 Bern, Switzerland
| | - Ludovic Gillet
- Pain Center, Department of Anesthesiology, University Hospital Center (CHUV) and Faculty of Biology and Medicine (FBM), University of Lausanne, 1011 Lausanne, Switzerland.,Department of Fundamental Neurosciences, Faculty of Biology and Medicine (FBM), University of Lausanne, 1005 Lausanne, Switzerland
| | - Irene Keller
- Department for BioMedical Research and Swiss Institute of Bioinformatics, University of Bern, 3007 Bern, Switzerland
| | - Hugues Abriel
- Ion Channels and Channelopathies Laboratory, Institute for Biochemistry and Molecular Medicine, University of Bern, 3012 Bern, Switzerland
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23
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Jones DC, Gong JQX, Sobie EA. A privileged role for neuronal Na + channels in regulating ventricular [Ca 2+] and arrhythmias. J Gen Physiol 2018; 150:901-905. [PMID: 29899058 PMCID: PMC6028496 DOI: 10.1085/jgp.201812120] [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] [Indexed: 11/20/2022] Open
Abstract
Jones et al. provide commentary on the intricate crosstalk between ion transporters that goes awry in long QT arrhythmia.
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Affiliation(s)
- DeAnalisa C Jones
- Department of Pharmacological Sciences, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Jingqi Q X Gong
- Department of Pharmacological Sciences, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Eric A Sobie
- Department of Pharmacological Sciences, Graduate School of Biomedical Sciences, Icahn School of Medicine at Mount Sinai, New York, NY
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24
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Li M, van Esch BCAM, Henricks PAJ, Folkerts G, Garssen J. The Anti-inflammatory Effects of Short Chain Fatty Acids on Lipopolysaccharide- or Tumor Necrosis Factor α-Stimulated Endothelial Cells via Activation of GPR41/43 and Inhibition of HDACs. Front Pharmacol 2018; 9:533. [PMID: 29875665 PMCID: PMC5974203 DOI: 10.3389/fphar.2018.00533] [Citation(s) in RCA: 179] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 05/02/2018] [Indexed: 12/22/2022] Open
Abstract
Background and Aim: Previously, we found that short chain fatty acids (SCFA) inhibit LPS or TNFα-induced endothelial inflammatory responses and excessive vascular cell adhesion molecule-1 (VCAM-1) expression, two important steps in the development of atherosclerosis. However, the mechanisms involved are still unclear. We hypothesized that the effects of SCFA are associated with activation of G-protein coupled receptor 41/43 (GPR41/43) and/or inhibition of histone deacetylases (HDACs). Methods: The expression and location of GPR41/43 and HDAC3 in human umbilical vein endothelial cells (HUVEC) were confirmed. HUVEC were pre-incubated with acetate, butyrate or propionate alone or in combination with GLPG0974 (GLPG, antagonist of GPR43) or β-hydroxybutyrate (SHB, antagonist of GPR41) and then exposed to LPS or TNFα. Interleukin (IL)-6 and IL-8 levels and VCAM-1 expression were measured. HDAC activity was measured after treatment with butyrate, propionate and trichostatin A (TSA, HDAC inhibitor). The peripheral blood mononuclear cell (PBMC) adhesive level was also determined after TSA treatment. Results: GPR41/43 were expressed on the membrane of HUVEC and HDAC3 was located in cytoplasm and nucleus. The GLPG and/or SHB treatments restored the inhibitory effects of acetate on IL-6 and IL-8 production and the inhibitory effects of butyrate or propionate on IL-6 production, but not on IL-8. In contrast, GLPG and/or SHB treatments did not affect the inhibitory effects of butyrate or propionate on TNFα-induced VCAM-1 expression. TSA showed similar effects on IL-8 production and VCAM-1 expression as butyrate and propionate. In addition, TSA significantly inhibited the adhesion of PBMC to an endothelial monolayer. Conclusion: Activation of GPR41/43 mediates the effects of acetate on IL-6 and IL-8 production and the effects of butyrate and propionate on IL-6 production. Furthermore, inhibition of HDACs mediates the effects of butyrate and propionate on IL-8 production, VCAM-1 expression, and PBMC adhesion to an endothelial monolayer. These data indicate the beneficial roles of SCFA in preventing vascular inflammation and relevant diseases by activation of GPR41/43 and inhibition of HDACs.
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Affiliation(s)
- Meng Li
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Betty C A M van Esch
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Utrecht, Netherlands.,Nutricia Research, Immunology, Utrecht, Netherlands
| | - Paul A J Henricks
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Gert Folkerts
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Johan Garssen
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Faculty of Science, Utrecht University, Utrecht, Netherlands.,Nutricia Research, Immunology, Utrecht, Netherlands
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25
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Koleske M, Bonilla I, Thomas J, Zaman N, Baine S, Knollmann BC, Veeraraghavan R, Györke S, Radwański PB. Tetrodotoxin-sensitive Na vs contribute to early and delayed afterdepolarizations in long QT arrhythmia models. J Gen Physiol 2018; 150:991-1002. [PMID: 29793933 PMCID: PMC6028491 DOI: 10.1085/jgp.201711909] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 03/30/2018] [Accepted: 04/30/2018] [Indexed: 01/08/2023] Open
Abstract
Neuronal Na+ channels contribute to catecholaminergic polymorphic ventricular tachycardia in the heart, but their role in other types of arrhythmias is unknown. Koleske et al. show that they contribute to early and delayed afterdepolarizations common to long QT, catecholaminergic polymorphic ventricular tachycardia, and overlap phenotypes. Recent evidence suggests that neuronal Na+ channels (nNavs) contribute to catecholamine-promoted delayed afterdepolarizations (DADs) and catecholaminergic polymorphic ventricular tachycardia (CPVT). The newly identified overlap between CPVT and long QT (LQT) phenotypes has stoked interest in the cross-talk between aberrant Na+ and Ca2+ handling and its contribution to early afterdepolarizations (EADs) and DADs. Here, we used Ca2+ imaging and electrophysiology to investigate the role of Na+ and Ca2+ handling in DADs and EADs in wild-type and cardiac calsequestrin (CASQ2)-null mice. In experiments, repolarization was impaired using 4-aminopyridine (4AP), whereas the L-type Ca2+ and late Na+ currents were augmented using Bay K 8644 (BayK) and anemone toxin II (ATX-II), respectively. The combination of 4AP and isoproterenol prolonged action potential duration (APD) and promoted aberrant Ca2+ release, EADs, and DADs in wild-type cardiomyocytes. Similarly, BayK in the absence of isoproterenol induced the same effects in CASQ2-null cardiomyocytes. In vivo, it prolonged the QT interval and, upon catecholamine challenge, precipitated wide QRS polymorphic ventricular tachycardia that resembled human torsades de pointes. Treatment with ATX-II produced similar effects at both the cellular level and in vivo. Importantly, nNav inhibition with riluzole or 4,9-anhydro-tetrodotoxin reduced the incidence of ATX-II–, BayK-, or 4AP-induced EADs, DADs, aberrant Ca2+ release, and VT despite only modestly mitigating APD prolongation. These data reveal the contribution of nNaVs to triggered arrhythmias in murine models of LQT and CPVT-LQT overlap phenotypes. We also demonstrate the antiarrhythmic impact of nNaV inhibition, independent of action potential and QT interval duration, and provide a basis for a mechanistically driven antiarrhythmic strategy.
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Affiliation(s)
- Megan Koleske
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH
| | - Ingrid Bonilla
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH.,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH
| | - Justin Thomas
- Division of Pharmacy Practice and Sciences, College of Pharmacy, The Ohio State University, Columbus, OH
| | - Naveed Zaman
- Division of Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH
| | - Stephen Baine
- Division of Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH
| | - Bjorn C Knollmann
- Division of Clinical Pharmacology, Vanderbilt University Medical School, Nashville, TN
| | - Rengasayee Veeraraghavan
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH.,Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH
| | - Sándor Györke
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH.,Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH
| | - Przemysław B Radwański
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH .,Division of Pharmacy Practice and Sciences, College of Pharmacy, The Ohio State University, Columbus, OH.,Division of Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH
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26
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Kubasov IV, Stepanov A, Bobkov D, Radwanski PB, Terpilowski MA, Dobretsov M, Gyorke S. Sub-cellular Electrical Heterogeneity Revealed by Loose Patch Recording Reflects Differential Localization of Sarcolemmal Ion Channels in Intact Rat Hearts. Front Physiol 2018; 9:61. [PMID: 29487533 PMCID: PMC5816904 DOI: 10.3389/fphys.2018.00061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 01/18/2018] [Indexed: 12/31/2022] Open
Abstract
The cardiac action potential (AP) is commonly recoded as an integral signal from isolated myocytes or ensembles of myocytes (with intracellular microelectrodes and extracellular macroelectrodes, respectively). These signals, however, do not provide a direct measure of activity of ion channels and transporters located in two major compartments of a cardiac myocyte: surface sarcolemma and the T-tubule system, which differentially contribute to impulse propagation and excitation-contraction (EC) coupling. In the present study we investigated electrical properties of myocytes within perfused intact rat heart employing loose patch recording with narrow-tip (2 μm diameter) extracellular electrodes. Using this approach, we demonstrated two distinct types of electric signals with distinct waveforms (single peak and multi-peak AP; AP1 and AP2, respectively) during intrinsic pacemaker activity. These two types of waveforms depend on the position of the electrode tip on the myocyte surface. Such heterogeneity of electrical signals was lost when electrodes of larger pipette diameter were used (5 or 10 μm), which indicates that the electric signal was assessed from a region of <5 μm. Importantly, both pharmacological and mathematical simulation based on transverse (T)-tubular distribution suggested that while the AP1 and the initial peak of AP2 are predominantly attributable to the fast, inward Na+ current in myocyte's surface sarcolemma, the late components of AP2 are likely representative of currents associated with L-type Ca2+ channel and Na+/Ca2+ exchanger (NCX) currents which are predominantly located in T-tubules. Thus, loose patch recording with narrow-tip pipette provides a valuable tool for studying cardiac electric activity on the subcellular level in the intact heart.
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Affiliation(s)
- Igor V. Kubasov
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, Saint-Petersburg, Russia
| | - Andrei Stepanov
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, Saint-Petersburg, Russia
- Institute of Cytology RAS, Saint-Petersburg, Russia
| | - Danila Bobkov
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, Saint-Petersburg, Russia
- Institute of Cytology RAS, Saint-Petersburg, Russia
| | - Przemysław B. Radwanski
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, Ohio State University, Columbus, OH, United States
- Division of Pharmacy Practice and Science, College of Pharmacy, Ohio State University, Columbus, OH, United States
| | - Maxim A. Terpilowski
- I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, Saint-Petersburg, Russia
| | - Maxim Dobretsov
- Department of Anesthesiology, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Sandor Gyorke
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, Ohio State University, Columbus, OH, United States
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27
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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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28
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Rapid negative inotropic effect induced by TNF-α in rat heart perfused related to PKC activation. Cytokine 2017; 107:65-69. [PMID: 29196133 DOI: 10.1016/j.cyto.2017.11.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 10/16/2017] [Accepted: 11/27/2017] [Indexed: 11/21/2022]
Abstract
Myocardial depression, frequently observed in septic shock, is mediated by circulating molecules such as cytokines. TNF-α appears to be the most important pro-inflammatory cytokine released during the early phase of a septic shock. It was previously shown that TNF-α had a negative inotropic effect on myocardium. Now, the aim of this study was to investigate the effects of the activation of PKC by TNF-α on heart function, and to determine if this cytokine could induce a decrease of membrane excitability. Isolated rat hearts (n = 6) were perfused with Tyrode solution containing TNF-α at 20 ng/ml during 30 min by using a Langendorff technique. Expressions of PKC-α and PKC-ε were analysed by western blot on membrane and cytosol proteins extracted from ventricular myocardium. Patch clamp was performed on freshly isolated cardiomyocytes (n = 8). Compared to control situation, 30 min of TNF-α perfusion led to cardiac dysfunction with a decrease of the heart rate (-83%), the force (-20%) and speed of relaxation (-18%) and the coronary flow (-25%). This is associated with an activation and a membrane targeting of both PKC-α and PKC-ε isoforms in ventricle with respectively +123% and +54% compared to control hearts. Nevertheless, TNF-α had no significant effect on voltage-gated sodium current (109.0%+/- 12.5) after addition of the cytokine when compared to control. These results showed that TNF-α had a negative inotropic effect on the isolated rat heart and can induce PKC activation leading to an impaired contractility of the heart. However the early heart dysfunction induced by the cytokine was not associated to a decrease of cardiomyocytes membrane excitability as it has been evidenced in skeletal muscle fibres.
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29
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Mishra V, Karumuri BK, Gautier NM, Liu R, Hutson TN, Vanhoof-Villalba SL, Vlachos I, Iasemidis L, Glasscock E. Scn2a deletion improves survival and brain-heart dynamics in the Kcna1-null mouse model of sudden unexpected death in epilepsy (SUDEP). Hum Mol Genet 2017; 26:2091-2103. [PMID: 28334922 DOI: 10.1093/hmg/ddx104] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 03/13/2017] [Indexed: 12/20/2022] Open
Abstract
People with epilepsy have greatly increased probability of premature mortality due to sudden unexpected death in epilepsy (SUDEP). Identifying which patients are most at risk of SUDEP is hindered by a complex genetic etiology, incomplete understanding of the underlying pathophysiology and lack of prognostic biomarkers. Here we evaluated heterozygous Scn2a gene deletion (Scn2a+/-) as a protective genetic modifier in the Kcna1 knockout mouse (Kcna1-/-) model of SUDEP, while searching for biomarkers of SUDEP risk embedded in electroencephalography (EEG) and electrocardiography (ECG) recordings. The human epilepsy gene Kcna1 encodes voltage-gated Kv1.1 potassium channels that act to dampen neuronal excitability whereas Scn2a encodes voltage-gated Nav1.2 sodium channels important for action potential initiation and conduction. SUDEP-prone Kcna1-/- mice with partial genetic ablation of Nav1.2 channels (i.e. Scn2a+/-; Kcna1-/-) exhibited a two-fold increase in survival. Classical analysis of EEG and ECG recordings separately showed significantly decreased seizure durations in Scn2a+/-; Kcna1-/- mice compared with Kcna1-/- mice, without substantial modification of cardiac abnormalities. Novel analysis of the EEG and ECG together revealed a significant reduction in EEG-ECG association in Kcna1-/- mice compared with wild types, which was partially restored in Scn2a+/-; Kcna1-/- mice. The degree of EEG-ECG association was also proportional to the survival rate of mice across genotypes. These results show that Scn2a gene deletion acts as protective genetic modifier of SUDEP and suggest measures of brain-heart association as potential indices of SUDEP susceptibility.
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Affiliation(s)
- Vikas Mishra
- Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA
| | - Bharat K Karumuri
- Biomedical Engineering, Louisiana Tech University, Ruston, LA 71272, USA
| | - Nicole M Gautier
- Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA
| | - Rui Liu
- Department of Mathematics and Statistics, Louisiana Tech University, Ruston, LA 71272, USA
| | - Timothy N Hutson
- Biomedical Engineering, Louisiana Tech University, Ruston, LA 71272, USA
| | - Stephanie L Vanhoof-Villalba
- Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA
| | - Ioannis Vlachos
- Department of Mathematics and Statistics, Louisiana Tech University, Ruston, LA 71272, USA
| | - Leonidas Iasemidis
- Biomedical Engineering, Louisiana Tech University, Ruston, LA 71272, USA
| | - Edward Glasscock
- Department of Cellular Biology and Anatomy, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA
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30
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Weinberg SH. Ephaptic coupling rescues conduction failure in weakly coupled cardiac tissue with voltage-gated gap junctions. CHAOS (WOODBURY, N.Y.) 2017; 27:093908. [PMID: 28964133 DOI: 10.1063/1.4999602] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Electrical conduction in cardiac tissue is usually considered to be primarily facilitated by gap junctions, providing a pathway between the intracellular spaces of neighboring cells. However, recent studies have highlighted the role of coupling via extracellular electric fields, also known as ephaptic coupling, particularly in the setting of reduced gap junction expression. Further, in the setting of reduced gap junctional coupling, voltage-dependent gating of gap junctions, an oft-neglected biophysical property in computational studies, produces a positive feedback that promotes conduction failure. We hypothesized that ephaptic coupling can break the positive feedback loop and rescue conduction failure in weakly coupled cardiac tissue. In a computational tissue model incorporating voltage-gated gap junctions and ephaptic coupling, we demonstrate that ephaptic coupling can rescue conduction failure in weakly coupled tissue. Further, ephaptic coupling increased conduction velocity in weakly coupled tissue, and importantly, reduced the minimum gap junctional coupling necessary for conduction, most prominently at fast pacing rates. Finally, we find that, although neglecting gap junction voltage-gating results in negligible differences in well coupled tissue, more significant differences occur in weakly coupled tissue, greatly underestimating the minimal gap junctional coupling that can maintain conduction. Our study suggests that ephaptic coupling plays a conduction-preserving role, particularly at rapid heart rates.
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Affiliation(s)
- S H Weinberg
- Virginia Commonwealth University, 401 West Main Street, Richmond, Virginia 23284, USA
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31
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Greer-Short A, George SA, Poelzing S, Weinberg SH. Revealing the Concealed Nature of Long-QT Type 3 Syndrome. Circ Arrhythm Electrophysiol 2017; 10:e004400. [PMID: 28213505 DOI: 10.1161/circep.116.004400] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 12/13/2016] [Indexed: 11/16/2022]
Abstract
BACKGROUND Gain-of-function mutations in the voltage-gated sodium channel (Nav1.5) are associated with the long-QT-3 (LQT3) syndrome. Nav1.5 is densely expressed at the intercalated disk, and narrow intercellular separation can modulate cell-to-cell coupling via extracellular electric fields and depletion of local sodium ion nanodomains. Models predict that significantly decreasing intercellular cleft widths slows conduction because of reduced sodium current driving force, termed "self-attenuation." We tested the novel hypothesis that self-attenuation can "mask" the LQT3 phenotype by reducing the driving force and late sodium current that produces early afterdepolarizations (EADs). METHODS AND RESULTS Acute interstitial edema was used to increase intercellular cleft width in isolated guinea pig heart experiments. In a drug-induced LQT3 model, acute interstitial edema exacerbated action potential duration prolongation and produced EADs, in particular, at slow pacing rates. In a computational cardiac tissue model incorporating extracellular electric field coupling, intercellular cleft sodium nanodomains, and LQT3-associated mutant channels, myocytes produced EADs for wide intercellular clefts, whereas for narrow clefts, EADs were suppressed. For both wide and narrow clefts, mutant channels were incompletely inactivated. However, for narrow clefts, late sodium current was reduced via self-attenuation, a protective negative feedback mechanism, masking EADs. CONCLUSIONS We demonstrated a novel mechanism leading to the concealing and revealing of EADs in LQT3 models. Simulations predict that this mechanism may operate independent of the specific mutation, suggesting that future therapies could target intercellular cleft separation as a compliment or alternative to sodium channels.
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Affiliation(s)
- Amara Greer-Short
- From the Virginia Tech Carilion Research Institute, Virginia Polytechnic Institute and State University, Roanoke (A.G.-S., S.A.G., S.P.); and Department of Biomedical Engineering, Virginia Commonwealth University, Richmond (S.H.W.)
| | - Sharon A George
- From the Virginia Tech Carilion Research Institute, Virginia Polytechnic Institute and State University, Roanoke (A.G.-S., S.A.G., S.P.); and Department of Biomedical Engineering, Virginia Commonwealth University, Richmond (S.H.W.)
| | - Steven Poelzing
- From the Virginia Tech Carilion Research Institute, Virginia Polytechnic Institute and State University, Roanoke (A.G.-S., S.A.G., S.P.); and Department of Biomedical Engineering, Virginia Commonwealth University, Richmond (S.H.W.).
| | - Seth H Weinberg
- From the Virginia Tech Carilion Research Institute, Virginia Polytechnic Institute and State University, Roanoke (A.G.-S., S.A.G., S.P.); and Department of Biomedical Engineering, Virginia Commonwealth University, Richmond (S.H.W.).
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32
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Veeraraghavan R, Györke S, Radwański PB. Neuronal sodium channels: emerging components of the nano-machinery of cardiac calcium cycling. J Physiol 2017; 595:3823-3834. [PMID: 28195313 DOI: 10.1113/jp273058] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 12/05/2016] [Indexed: 01/07/2023] Open
Abstract
Excitation-contraction coupling is the bridge between cardiac electrical activation and mechanical contraction. It is driven by the influx of Ca2+ across the sarcolemma triggering Ca2+ release from the sarcoplasmic reticulum (SR) - a process termed Ca2+ -induced Ca2+ release (CICR) - followed by re-sequestration of Ca2+ into the SR. The Na+ /Ca2+ exchanger inextricably couples the cycling of Ca2+ and Na+ in cardiac myocytes. Thus, influx of Na+ via voltage-gated Na+ channels (NaV ) has emerged as an important regulator of CICR both in health and in disease. Recent insights into the subcellular distribution of cardiac and neuronal NaV isoforms and their ultrastructural milieu have important implications for the roles of these channels in mediating Ca2+ -driven arrhythmias. This review will discuss functional insights into the role of neuronal NaV isoforms vis-à-vis cardiac NaV s in triggering such arrhythmias and their potential as therapeutic targets in the context of the aforementioned structural observations.
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Affiliation(s)
- Rengasayee Veeraraghavan
- Virginia Tech Carilion Research Institute, and Center for Heart and Regenerative Medicine, Virginia Polytechnic University, Roanoke, VA, USA
| | - Sándor Györke
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, Ohio State University Wexner Medical Center, 473 West 12th Avenue, Room 510, Columbus, OH, 43210, USA.,Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, OH, USA
| | - Przemysław B Radwański
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, Ohio State University Wexner Medical Center, 473 West 12th Avenue, Room 510, Columbus, OH, 43210, USA.,Department of Physiology and Cell Biology, College of Medicine, Ohio State University, Columbus, OH, USA.,Division of Pharmacy Practice and Science, College of Pharmacy, Ohio State University, Columbus, OH, USA
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33
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Chen-Izu Y, Izu LT. Mechano-chemo-transduction in cardiac myocytes. J Physiol 2017; 595:3949-3958. [PMID: 28098356 DOI: 10.1113/jp273101] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 12/15/2016] [Indexed: 12/31/2022] Open
Abstract
The heart has the ability to adjust to changing mechanical loads. The Frank-Starling law and the Anrep effect describe exquisite intrinsic mechanisms the heart has for autoregulating the force of contraction to maintain cardiac output under changes of preload and afterload. Although these mechanisms have been known for more than a century, their cellular and molecular underpinnings are still debated. How does the cardiac myocyte sense changes in preload or afterload? How does the myocyte adjust its response to compensate for such changes? In cardiac myocytes Ca2+ is a crucial regulator of contractile force and in this review we compare and contrast recent studies from different labs that address these two important questions. The 'dimensionality' of the mechanical milieu under which experiments are carried out provide important clues to the location of the mechanosensors and the kinds of mechanical forces they can sense and respond to. As a first approximation, sensors inside the myocyte appear to modulate reactive oxygen species while sensors on the cell surface appear to also modulate nitric oxide signalling; both signalling pathways affect Ca2+ handling. Undoubtedly, further studies will add layers to this simplified picture. Clarifying the intimate links from cellular mechanics to reactive oxygen species and nitric oxide signalling and to Ca2+ handling will deepen our understanding of the Frank-Starling law and the Anrep effect, and also provide a unified view on how arrhythmias may arise in seemingly disparate diseases that have in common altered myocyte mechanics.
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Affiliation(s)
- Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, CA, 95616, USA.,Department of Biomedical Engineering, University of California, Davis, CA, 95616, USA.,Department of Internal Medicine/Division of Cardiology, University of California, Davis, CA, 95616, USA
| | - Leighton T Izu
- Department of Pharmacology, University of California, Davis, CA, 95616, USA
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34
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Finlay M, Harmer SC, Tinker A. The control of cardiac ventricular excitability by autonomic pathways. Pharmacol Ther 2017; 174:97-111. [PMID: 28223225 DOI: 10.1016/j.pharmthera.2017.02.023] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Central to the genesis of ventricular cardiac arrhythmia are variations in determinants of excitability. These involve individual ionic channels and transporters in cardiac myocytes but also tissue factors such as variable conduction of the excitation wave, fibrosis and source-sink mismatch. It is also known that in certain diseases and particularly the channelopathies critical events occur with specific stressors. For example, in hereditary long QT syndrome due to mutations in KCNQ1 arrhythmic episodes are provoked by exercise and in particular swimming. Thus not only is the static substrate important but also how this is modified by dynamic signalling events associated with common physiological responses. In this review, we examine the regulation of ventricular excitability by signalling pathways from a cellular and tissue perspective in an effort to identify key processes, effectors and potential therapeutic approaches. We specifically focus on the autonomic nervous system and related signalling pathways.
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Affiliation(s)
- Malcolm Finlay
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Charterhouse Square, London EC1M6BQ, UK
| | - Stephen C Harmer
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Charterhouse Square, London EC1M6BQ, UK
| | - Andrew Tinker
- The Heart Centre, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Charterhouse Square, London EC1M6BQ, UK.
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35
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Israel MR, Tay B, Deuis JR, Vetter I. Sodium Channels and Venom Peptide Pharmacology. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2017; 79:67-116. [PMID: 28528674 DOI: 10.1016/bs.apha.2017.01.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Venomous animals including cone snails, spiders, scorpions, anemones, and snakes have evolved a myriad of components in their venoms that target the opening and/or closing of voltage-gated sodium channels to cause devastating effects on the neuromuscular systems of predators and prey. These venom peptides, through design and serendipity, have not only contributed significantly to our understanding of sodium channel pharmacology and structure, but they also represent some of the most phyla- and isoform-selective molecules that are useful as valuable tool compounds and drug leads. Here, we review our understanding of the basic function of mammalian voltage-gated sodium channel isoforms as well as the pharmacology of venom peptides that act at these key transmembrane proteins.
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Affiliation(s)
- Mathilde R Israel
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Bryan Tay
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Jennifer R Deuis
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia.
| | - Irina Vetter
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia; School of Pharmacy, The University of Queensland, Brisbane, QLD, Australia.
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Cardiac arrhythmia in a mouse model of sodium channel SCN8A epileptic encephalopathy. Proc Natl Acad Sci U S A 2016; 113:12838-12843. [PMID: 27791149 DOI: 10.1073/pnas.1612746113] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Patients with early infantile epileptic encephalopathy (EIEE) are at increased risk for sudden unexpected death in epilepsy (SUDEP). De novo mutations of the sodium channel gene SCN8A, encoding the sodium channel Nav1.6, result in EIEE13 (OMIM 614558), which has a 10% risk of SUDEP. Here, we investigated the cardiac phenotype of a mouse model expressing the gain of function EIEE13 patient mutation p.Asn1768Asp in Scn8a (Nav1.6-N1768D). We tested Scn8aN1768D/+ mice for alterations in cardiac excitability. We observed prolongation of the early stages of action potential (AP) repolarization in mutant myocytes vs. controls. Scn8aN1768D/+ myocytes were hyperexcitable, with a lowered threshold for AP firing, increased incidence of delayed afterdepolarizations, increased calcium transient duration, increased incidence of diastolic calcium release, and ectopic contractility. Calcium transient duration and diastolic calcium release in the mutant myocytes were tetrodotoxin-sensitive. A selective inhibitor of reverse mode Na/Ca exchange blocked the increased incidence of diastolic calcium release in mutant cells. Scn8aN1768D/+ mice exhibited bradycardia compared with controls. This difference in heart rate dissipated after administration of norepinephrine, and there were no differences in heart rate in denervated ex vivo hearts, implicating parasympathetic hyperexcitability in the Scn8aN1768D/+ animals. When challenged with norepinephrine and caffeine to simulate a catecholaminergic surge, Scn8aN1768D/+ mice showed ventricular arrhythmias. Two of three mutant mice under continuous ECG telemetry recording experienced death, with severe bradycardia preceding asystole. Thus, in addition to central neuron hyperexcitability, Scn8aN1768D/+ mice have cardiac myoycte and parasympathetic neuron hyperexcitability. Simultaneous dysfunction in these systems may contribute to SUDEP associated with mutations of Scn8a.
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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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Abstract
Sick excitable cells (ie, Nav channel-expressing cells injured by trauma, ischemia, inflammatory, and other conditions) typically exhibit "acquired sodium channelopathies" which, we argue, reflect bleb-damaged membranes rendering their Nav channels "leaky." The situation is excitotoxic because untreated Nav leak exacerbates bleb damage. Fast Nav inactivation (a voltage-independent process) is so tightly coupled, kinetically speaking, to the inherently voltage-dependent process of fast activation that when bleb damage accelerates and thus left-shifts macroscopic fast activation, fast inactivation accelerates to the same extent. The coupled g(V) and availability(V) processes and their window conductance regions consequently left-shift by the same number of millivolts. These damage-induced hyperpolarizing shifts, whose magnitude increases with damage intensity, are called coupled left shift (CLS). Based on past work and modeling, we discuss how to test for Nav-CLS, emphasizing the virtue of sawtooth ramp clamp. We explain that it is the inherent mechanosensitivity of Nav activation that underlies Nav-CLS. Using modeling of excitability, we show the known process of Nav-CLS is sufficient to predict a wide variety of "sick excitable cell" phenomena, from hyperexcitability through to depolarizing block. When living cells are mimicked by inclusion of pumps, mild Nav-CLS produces a wide array of burst phenomena and subthreshold oscillations. Dynamical analysis of mild damage scenarios shows how these phenomena reflect changes in spike thresholds as the pumps try to counteract the leaky Nav channels. Smart Nav inhibitors designed for sick excitable cells would target bleb-damaged membrane, buying time for cell-mediated removal or repair of Nav-bearing membrane that has become bleb-damaged (ie, detached from the cytoskeleton).
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Affiliation(s)
- C E Morris
- Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - B Joos
- University of Ottawa, Ottawa, ON, Canada
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Radwański PB, Ho HT, Veeraraghavan R, Brunello L, Liu B, Belevych AE, Unudurthi SD, Makara MA, Priori SG, Volpe P, Armoundas AA, Dillmann WH, Knollmann BC, Mohler PJ, Hund TJ, Györke S. Neuronal Na + Channels Are Integral Components of Pro-arrhythmic Na +/Ca 2+ Signaling Nanodomain That Promotes Cardiac Arrhythmias During β-adrenergic Stimulation. JACC Basic Transl Sci 2016; 1:251-266. [PMID: 27747307 PMCID: PMC5065245 DOI: 10.1016/j.jacbts.2016.04.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Cardiac arrhythmias are a leading cause of death in the US. Vast majority of these arrhythmias including catecholaminergic polymorphic ventricular tachycardia (CPVT) are associated with increased levels of circulating catecholamines and involve abnormal impulse formation secondary to aberrant Ca2+ and Na+ handling. However, the mechanistic link between β-AR stimulation and the subcellular/molecular arrhythmogenic trigger(s) remains elusive. METHODS AND RESULTS We performed functional and structural studies to assess Ca2+ and Na+ signaling in ventricular myocyte as well as surface electrocardiograms in mouse models of cardiac calsequestrin (CASQ2)-associated CPVT. We demonstrate that a subpopulation of Na+ channels (neuronal Na+ channels; nNav) that colocalize with RyR2 and Na+/Ca2+ exchanger (NCX) are a part of the β-AR-mediated arrhythmogenic process. Specifically, augmented Na+ entry via nNav in the settings of genetic defects within the RyR2 complex and enhanced sarcoplasmic reticulum (SR) Ca2+-ATPase (SERCA)-mediated SR Ca2+ refill is both an essential and a necessary factor for the arrhythmogenesis. Furthermore, we show that augmentation of Na+ entry involves β-AR-mediated activation of CAMKII subsequently leading to nNav augmentation. Importantly, selective pharmacological inhibition as well as silencing of Nav1.6 inhibit myocyte arrhythmic potential and prevent arrhythmias in vivo. CONCLUSION These data suggest that the arrhythmogenic alteration in Na+/Ca2+ handling evidenced ruing β-AR stimulation results, at least in part, from enhanced Na+ influx through nNav. Therefore, selective inhibition of these channels and Nav1.6 in particular can serve as a potential antiarrhythmic therapy.
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Affiliation(s)
- Przemysław B Radwański
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA ; Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, US ; Division of Pharmacy Practice and Sciences, College of Pharmacy, The Ohio State University, Columbus, OH, US
| | - Hsiang-Ting Ho
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA ; Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, US
| | - Rengasayee Veeraraghavan
- Center for Heart and Regenerative Medicine Research, Virginia Tech Carilion Research Institute, Virginia Polytechnic University, Roanoke, VA, USA
| | - Lucia Brunello
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA ; Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, US
| | - Bin Liu
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA ; Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, US
| | - Andriy E Belevych
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA ; Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, US
| | - Sathya D Unudurthi
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA ; Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH, USA
| | - Michael A Makara
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA ; Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, US
| | - Silvia G Priori
- Division of Cardiology and Molecular Cardiology, Maugeri Foundation-University of Pavia, Pavia, Italy
| | - Pompeo Volpe
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Antonis A Armoundas
- Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, MA, USA
| | - Wolfgang H Dillmann
- Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Bjorn C Knollmann
- Division of Clinical Pharmacology, Vanderbilt University Medical School, Nashville, TN, USA
| | - Peter J Mohler
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA ; Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, US
| | - Thomas J Hund
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA ; Center for Heart and Regenerative Medicine Research, Virginia Tech Carilion Research Institute, Virginia Polytechnic University, Roanoke, VA, USA
| | - Sándor Györke
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA ; Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, US
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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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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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George SA, Poelzing S. Cardiac conduction in isolated hearts of genetically modified mice--Connexin43 and salts. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 120:189-98. [PMID: 26627143 DOI: 10.1016/j.pbiomolbio.2015.11.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Revised: 11/13/2015] [Accepted: 11/23/2015] [Indexed: 10/22/2022]
Abstract
Physiologic variations in perfusate composition have been identified as a new and important modulator of cardiac conduction velocity (CV), particularly when gap junctions (GJ) are reduced. We recently demonstrated in ex vivo hearts that perfusates with low sodium and high potassium preferentially slow ventricular CV in mice genetically engineered to express 50% less of the gap junction protein, connexin43 (Cx43). We also reported the possible role of calcium in modulating CV. In this review we discuss previous murine studies that explored the CV-GJ relationship in isolated mouse heart preparations with approximately 50% reduced Cx43. Studies were grouped according to the type of perfusate utilized, and CV during GJ uncoupling was compared. Studies in Group A preferentially used perfusates with low sodium, high potassium and non-physiologic calcium, and found CV slows and arrhythmias increase in mouse hearts with reduced Cx43. Studies in Group B used solutions with high sodium, low potassium and physiologic calcium, and did not observe CV slowing nor increased arrhythmia risk with loss of Cx3. Studies in Group C used solutions with low sodium, low potassium, physiologic calcium, creatine, taurine, and insulin. CV slowing was not observed, nor was arrhythmia risk increased with loss of Cx43. We suggest that perfusate ion composition may be a major determinant of whether CV slows when Cx43 is reduced. Furthermore, the review of these studies highlights important theoretical developments in the understanding of cardiac conduction and suggests that ionic milieu can conceal electrophysiologic remodeling secondary to reduced Cx43 expression as occurs in many cardiac diseases.
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Affiliation(s)
- Sharon A George
- Department of Biomedical Engineering and Mechanics, Virginia Tech Carilion Research Institute, and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
| | - Steven Poelzing
- Department of Biomedical Engineering and Mechanics, Virginia Tech Carilion Research Institute, and Center for Heart and Regenerative Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
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Biet M, Morin N, Lessard-Beaudoin M, Graham RK, Duss S, Gagné J, Sanon NT, Carmant L, Dumaine R. Prolongation of Action Potential Duration and QT Interval During Epilepsy Linked to Increased Contribution of Neuronal Sodium Channels to Cardiac Late Na
+
Current. Circ Arrhythm Electrophysiol 2015; 8:912-20. [DOI: 10.1161/circep.114.002693] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 06/01/2015] [Indexed: 11/16/2022]
Affiliation(s)
- Michael Biet
- From the Département de Pharmacologie et Physiologie, Université de Sherbrooke, Sherbrooke, Canada (M.B., N.M., M.L.-B., R.K.G., R.D.); and Department of Pediatrics, Centre de Recherche du CHU Sainte Justine, Université de Montréal, Montréal, Quebec, Canada (S.D., J.G., N.T.S., L.C.)
| | - Nathalie Morin
- From the Département de Pharmacologie et Physiologie, Université de Sherbrooke, Sherbrooke, Canada (M.B., N.M., M.L.-B., R.K.G., R.D.); and Department of Pediatrics, Centre de Recherche du CHU Sainte Justine, Université de Montréal, Montréal, Quebec, Canada (S.D., J.G., N.T.S., L.C.)
| | - Melissa Lessard-Beaudoin
- From the Département de Pharmacologie et Physiologie, Université de Sherbrooke, Sherbrooke, Canada (M.B., N.M., M.L.-B., R.K.G., R.D.); and Department of Pediatrics, Centre de Recherche du CHU Sainte Justine, Université de Montréal, Montréal, Quebec, Canada (S.D., J.G., N.T.S., L.C.)
| | - Rona K. Graham
- From the Département de Pharmacologie et Physiologie, Université de Sherbrooke, Sherbrooke, Canada (M.B., N.M., M.L.-B., R.K.G., R.D.); and Department of Pediatrics, Centre de Recherche du CHU Sainte Justine, Université de Montréal, Montréal, Quebec, Canada (S.D., J.G., N.T.S., L.C.)
| | - Sandra Duss
- From the Département de Pharmacologie et Physiologie, Université de Sherbrooke, Sherbrooke, Canada (M.B., N.M., M.L.-B., R.K.G., R.D.); and Department of Pediatrics, Centre de Recherche du CHU Sainte Justine, Université de Montréal, Montréal, Quebec, Canada (S.D., J.G., N.T.S., L.C.)
| | - Jonathan Gagné
- From the Département de Pharmacologie et Physiologie, Université de Sherbrooke, Sherbrooke, Canada (M.B., N.M., M.L.-B., R.K.G., R.D.); and Department of Pediatrics, Centre de Recherche du CHU Sainte Justine, Université de Montréal, Montréal, Quebec, Canada (S.D., J.G., N.T.S., L.C.)
| | - Nathalie T. Sanon
- From the Département de Pharmacologie et Physiologie, Université de Sherbrooke, Sherbrooke, Canada (M.B., N.M., M.L.-B., R.K.G., R.D.); and Department of Pediatrics, Centre de Recherche du CHU Sainte Justine, Université de Montréal, Montréal, Quebec, Canada (S.D., J.G., N.T.S., L.C.)
| | - Lionel Carmant
- From the Département de Pharmacologie et Physiologie, Université de Sherbrooke, Sherbrooke, Canada (M.B., N.M., M.L.-B., R.K.G., R.D.); and Department of Pediatrics, Centre de Recherche du CHU Sainte Justine, Université de Montréal, Montréal, Quebec, Canada (S.D., J.G., N.T.S., L.C.)
| | - Robert Dumaine
- From the Département de Pharmacologie et Physiologie, Université de Sherbrooke, Sherbrooke, Canada (M.B., N.M., M.L.-B., R.K.G., R.D.); and Department of Pediatrics, Centre de Recherche du CHU Sainte Justine, Université de Montréal, Montréal, Quebec, Canada (S.D., J.G., N.T.S., L.C.)
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Roger S, Gillet L, Le Guennec JY, Besson P. Voltage-gated sodium channels and cancer: is excitability their primary role? Front Pharmacol 2015; 6:152. [PMID: 26283962 PMCID: PMC4518325 DOI: 10.3389/fphar.2015.00152] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Accepted: 07/09/2015] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium channels (NaV) are molecular characteristics of excitable cells. Their activation, triggered by membrane depolarization, generates transient sodium currents that initiate action potentials in neurons and muscle cells. Sodium currents were discovered by Hodgkin and Huxley using the voltage clamp technique and reported in their landmark series of papers in 1952. It was only in the 1980's that sodium channel proteins from excitable membranes were molecularly characterized by Catterall and his collaborators. Non-excitable cells can also express NaV channels in physiological conditions as well as in pathological conditions. These NaV channels can sustain biological roles that are not related to the generation of action potentials. Interestingly, it is likely that the abnormal expression of NaV in pathological tissues can reflect the re-expression of a fetal phenotype. This is especially true in epithelial cancer cells for which these channels have been identified and sodium currents recorded, while it was not the case for cells from the cognate normal tissues. In cancers, the functional activity of NaV appeared to be involved in regulating the proliferative, migrative, and invasive properties of cells. This review is aimed at addressing the non-excitable roles of NaV channels with a specific emphasis in the regulation of cancer cell biology.
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Affiliation(s)
- Sébastien Roger
- Inserm UMR1069, Nutrition, Croissance et Cancer, Université François-Rabelais de Tours Tours, France ; Département de Physiologie Animale, UFR Sciences and Techniques, Université François-Rabelais de Tours Tours, France
| | - Ludovic Gillet
- Department of Clinical Research, University of Bern Bern, Switzerland
| | | | - Pierre Besson
- Inserm UMR1069, Nutrition, Croissance et Cancer, Université François-Rabelais de Tours Tours, France
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Gap Junction-associated Na+ Influx Is Involved in the Mediation of Ca2+ Transients in Neonatal Rat Ventricular Myocytes. J Cardiovasc Pharmacol 2015; 66:41-9. [DOI: 10.1097/fjc.0000000000000241] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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46
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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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47
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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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Radwański PB, Brunello L, Veeraraghavan R, Ho HT, Lou Q, Makara MA, Belevych AE, Anghelescu M, Priori SG, Volpe P, Hund TJ, Janssen PML, Mohler PJ, Bridge JHB, Poelzing S, Györke S. Neuronal Na+ channel blockade suppresses arrhythmogenic diastolic Ca2+ release. Cardiovasc Res 2014; 106:143-52. [PMID: 25538156 DOI: 10.1093/cvr/cvu262] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
AIMS Sudden death resulting from cardiac arrhythmias is the most common consequence of cardiac disease. Certain arrhythmias caused by abnormal impulse formation including catecholaminergic polymorphic ventricular tachycardia (CPVT) are associated with delayed afterdepolarizations resulting from diastolic Ca2+ release (DCR) from the sarcoplasmic reticulum (SR). Despite high response of CPVT to agents directly affecting Ca2+ cycling, the incidence of refractory cases is still significant. Surprisingly, these patients often respond to treatment with Na+ channel blockers. However, the relationship between Na+ influx and disturbances in Ca2+ handling immediately preceding arrhythmias in CPVT remains poorly understood and is the object of this study. METHODS AND RESULTS We performed optical Ca2+ and membrane potential imaging in ventricular myocytes and intact cardiac muscles as well as surface ECGs on a CPVT mouse model with a mutation in cardiac calsequestrin. We demonstrate that a subpopulation of Na+ channels (neuronal Na+ channels; nNav) colocalize with ryanodine receptor Ca2+ release channels (RyR2). Disruption of the crosstalk between nNav and RyR2 by nNav blockade with riluzole reduced and also desynchronized DCR in isolated cardiomyocytes and in intact cardiac tissue. Such desynchronization of DCR on cellular and tissue level translated into decreased arrhythmias in CPVT mice. CONCLUSIONS Thus, our study offers the first evidence that nNav contribute to arrhythmogenic DCR, thereby providing a conceptual basis for mechanism-based antiarrhythmic therapy.
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Affiliation(s)
- Przemysław B Radwański
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, 473 West 12th Avenue, Room 507, Columbus, OH 43210, USA Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA Division of Pharmacy Practice and Administration, College of Pharmacy, The Ohio State University, Columbus, OH, USA
| | - Lucia Brunello
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, 473 West 12th Avenue, Room 507, Columbus, OH 43210, USA Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Rengasayee Veeraraghavan
- VTC Research Institute, School of Biomedical Engineering and Sciences, Virginia Tech, Roanoke, VA, USA
| | - Hsiang-Ting Ho
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, 473 West 12th Avenue, Room 507, Columbus, OH 43210, USA Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Qing Lou
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, 473 West 12th Avenue, Room 507, Columbus, OH 43210, USA Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Michael A Makara
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, 473 West 12th Avenue, Room 507, Columbus, OH 43210, USA Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Andriy E Belevych
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, 473 West 12th Avenue, Room 507, Columbus, OH 43210, USA Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Mircea Anghelescu
- Department of Biological and Allied Health Sciences, Ohio Northern University, Ada, OH, USA
| | - Silvia G Priori
- Division of Cardiology and Molecular Cardiology, Maugeri Foundation-University of Pavia, Pavia, Italy
| | - Pompeo Volpe
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Thomas J Hund
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, 473 West 12th Avenue, Room 507, Columbus, OH 43210, USA
| | - Paul M L Janssen
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, 473 West 12th Avenue, Room 507, Columbus, OH 43210, USA Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Peter J Mohler
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, 473 West 12th Avenue, Room 507, Columbus, OH 43210, USA Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA Department of Internal Medicine, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - John H B Bridge
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, UT, USA
| | - Steven Poelzing
- VTC Research Institute, School of Biomedical Engineering and Sciences, Virginia Tech, Roanoke, VA, USA
| | - Sándor Györke
- Dorothy M. Davis Heart and Lung Research Institute, College of Medicine, The Ohio State University Wexner Medical Center, 473 West 12th Avenue, Room 507, Columbus, OH 43210, USA Department of Physiology and Cell Biology, College of Medicine, The Ohio State University, Columbus, OH, USA
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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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50
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Lin X, O'Malley H, Chen C, Auerbach D, Foster M, Shekhar A, Zhang M, Coetzee W, Jalife J, Fishman GI, Isom L, Delmar M. Scn1b deletion leads to increased tetrodotoxin-sensitive sodium current, altered intracellular calcium homeostasis and arrhythmias in murine hearts. J Physiol 2014; 593:1389-407. [PMID: 25772295 DOI: 10.1113/jphysiol.2014.277699] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 08/07/2014] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Na(+) current (INa) results from the integrated function of a molecular aggregate (the voltage-gated Na(+) channel complex) that includes the β subunit family. Mutations or rare variants in Scn1b (encoding the β1 and β1B subunits) have been associated with various inherited arrhythmogenic syndromes, including Brugada syndrome and sudden unexpected death in patients with epilepsy. We used Scn1b null mice to understand better the relation between Scn1b expression, and cardiac electrical function. Loss of Scn1b caused, among other effects, increased amplitude of tetrodotoxin-sensitive INa, delayed after-depolarizations, triggered beats, delayed Ca(2+) transients, frequent spontaneous calcium release events and increased susceptibility to polymorphic ventricular arrhythmias. Most alterations in Ca(2+) homeostasis were prevented by 100 nM tetrodotoxin. We propose that life-threatening arrhythmias in patients with mutations in Scn1b, a gene classically defined as ancillary to the Na(+) channel α subunit, can be partly consequent to disrupted intracellular Ca(2+) homeostasis. ABSTRACT Na(+) current (INa) is determined not only by the properties of the pore-forming voltage-gated Na(+) channel (VGSC) α subunit, but also by the integrated function of a molecular aggregate (the VGSC complex) that includes the VGSC β subunit family. Mutations or rare variants in Scn1b (encoding the β1 and β1B subunits) have been associated with various inherited arrhythmogenic syndromes, including cases of Brugada syndrome and sudden unexpected death in patients with epilepsy. Here, we have used Scn1b null mouse models to understand better the relation between Scn1b expression, and cardiac electrical function. Using a combination of macropatch and scanning ion conductance microscopy we show that loss of Scn1b in juvenile null animals resulted in increased tetrodotoxin-sensitive INa but only in the cell midsection, even before full T-tubule formation; the latter occurred concurrent with increased message abundance for the neuronal Scn3a mRNA, suggesting increased abundance of tetrodotoxin-sensitive NaV 1.3 protein and yet its exclusion from the region of the intercalated disc. Ventricular myocytes from cardiac-specific adult Scn1b null animals showed increased Scn3a message, prolonged action potential repolarization, presence of delayed after-depolarizations and triggered beats, delayed Ca(2+) transients and frequent spontaneous Ca(2+) release events and at the whole heart level, increased susceptibility to polymorphic ventricular arrhythmias. Most alterations in Ca(2+) homeostasis were prevented by 100 nM tetrodotoxin. Our results suggest that life-threatening arrhythmias in patients with mutations in Scn1b, a gene classically defined as ancillary to the Na(+) channel α subunit, can be partly consequent to disrupted intracellular Ca(2+) homeostasis in ventricular myocytes.
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Affiliation(s)
- Xianming Lin
- Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, NY, USA
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