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Hamaguchi S, Agata N, Seki M, Namekata I, Tanaka H. Developmental Changes in the Excitation-Contraction Mechanisms of the Ventricular Myocardium and Their Sympathetic Regulation in Small Experimental Animals. J Cardiovasc Dev Dis 2024; 11:267. [PMID: 39330325 PMCID: PMC11432613 DOI: 10.3390/jcdd11090267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Revised: 08/02/2024] [Accepted: 08/11/2024] [Indexed: 09/28/2024] Open
Abstract
The developmental changes in the excitation-contraction mechanisms of the ventricular myocardium of small animals (guinea pig, rat, mouse) and their sympathetic regulation will be summarized. The action potential duration monotonically decreases during pre- and postnatal development in the rat and mouse, while in the guinea pig it decreases during the fetal stage but turns into an increase just before birth. Such changes can be attributed to changes in the repolarizing potassium currents. The T-tubule and the sarcoplasmic reticulum are scarcely present in the fetal cardiomyocyte, but increase during postnatal development. This causes a developmental shift in the Ca2+ handling from a sarcolemma-dependent mechanism to a sarcoplasmic reticulum-dependent mechanism. The sensitivity for beta-adrenoceptor-mediated positive inotropy decreases during early postnatal development, which parallels the increase in sympathetic nerve innervation. The alpha-adrenoceptor-mediated inotropy in the mouse changes from positive in the neonate to negative in the adult. This can be explained by the change in the excitation-contraction mechanism mentioned above. The shortening of the action potential duration enhances trans-sarcolemmal Ca2+ extrusion by the Na+-Ca2+ exchanger. The sarcoplasmic reticulum-dependent mechanism of contraction in the adult allows Na+-Ca2+ exchanger activity to cause negative inotropy, a mechanism not observed in neonatal myocardium. Such developmental studies would provide clues towards a more comprehensive understanding of cardiac function.
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Affiliation(s)
| | | | | | | | - Hikaru Tanaka
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Toho University, Funabashi 274-8510, Japan; (S.H.); (N.A.); (M.S.); (I.N.)
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2
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Garbutt TA, Wang Z, Wang H, Ma H, Ruan H, Dong Y, Xie Y, Tan L, Phookan R, Stouffer J, Vedantham V, Yang Y, Qian L, Liu J. Epigenetic Regulation of Cardiomyocyte Maturation by Arginine Methyltransferase CARM1. Circulation 2024; 149:1501-1515. [PMID: 38223978 PMCID: PMC11073921 DOI: 10.1161/circulationaha.121.055738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 12/19/2023] [Indexed: 01/16/2024]
Abstract
BACKGROUND During the neonatal stage, the cardiomyocyte undergoes a constellation of molecular, cytoarchitectural, and functional changes known collectively as cardiomyocyte maturation to increase myocardial contractility and cardiac output. Despite the importance of cardiomyocyte maturation, the molecular mechanisms governing this critical process remain largely unexplored. METHODS We leveraged an in vivo mosaic knockout system to characterize the role of Carm1, the founding member of protein arginine methyltransferase, in cardiomyocyte maturation. Using a battery of assays, including immunohistochemistry, immuno-electron microscopy imaging, and action potential recording, we assessed the effect of loss of Carm1 function on cardiomyocyte cell growth, myofibril expansion, T-tubule formation, and electrophysiological maturation. Genome-wide transcriptome profiling, H3R17me2a chromatin immunoprecipitation followed by sequencing, and assay for transposase-accessible chromatin with high-throughput sequencing were used to investigate the mechanisms by which CARM1 (coactivator-associated arginine methyltransferase 1) regulates cardiomyocyte maturation. Finally, we interrogated the human syntenic region to the H3R17me2a chromatin immunoprecipitation followed by sequencing peaks for single-nucleotide polymorphisms associated with human heart diseases. RESULTS We report that mosaic ablation of Carm1 disrupts multiple aspects of cardiomyocyte maturation cell autonomously, leading to reduced cardiomyocyte size and sarcomere thickness, severe loss and disorganization of T tubules, and compromised electrophysiological maturation. Genomics study demonstrates that CARM1 directly activates genes that underlie cardiomyocyte cytoarchitectural and electrophysiological maturation. Moreover, our study reveals significant enrichment of human heart disease-associated single-nucleotide polymorphisms in the human genomic region syntenic to the H3R17me2a chromatin immunoprecipitation followed by sequencing peaks. CONCLUSIONS This study establishes a critical and multifaceted role for CARM1 in regulating cardiomyocyte maturation and demonstrates that deregulation of CARM1-dependent cardiomyocyte maturation gene expression may contribute to human heart diseases.
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Affiliation(s)
- Tiffany A. Garbutt
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Zhenhua Wang
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
- Department of Cardiovascular Surgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Haofei Wang
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Hong Ma
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
- Present address: Department of Cardiology, 2 Affiliated Hospital, School of Medicine, Zhejiang University. Hangzhou 310009, China
| | - Hongmei Ruan
- Department of Medicine and Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Yanhan Dong
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Yifang Xie
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Lianmei Tan
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Ranan Phookan
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Joy Stouffer
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Vasanth Vedantham
- Department of Medicine and Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Yuchen Yang
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Li Qian
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jiandong Liu
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
- McAllister Heart Institute, University of North Carolina, Chapel Hill, NC 27599, USA
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Silva Dos Santos D, Turaça LT, Coutinho KCDS, Barbosa RAQ, Polidoro JZ, Kasai-Brunswick TH, Campos de Carvalho AC, Girardi ACC. Empagliflozin reduces arrhythmogenic effects in rat neonatal and human iPSC-derived cardiomyocytes and improves cytosolic calcium handling at least partially independent of NHE1. Sci Rep 2023; 13:8689. [PMID: 37248416 DOI: 10.1038/s41598-023-35944-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 05/26/2023] [Indexed: 05/31/2023] Open
Abstract
The antidiabetic agent class of sodium-glucose cotransporter 2 (SGLT2) inhibitors confer unprecedented cardiovascular benefits beyond glycemic control, including reducing the risk of fatal ventricular arrhythmias. However, the impact of SGLT2 inhibitors on the electrophysiological properties of cardiomyocytes exposed to stimuli other than hyperglycemia remains elusive. This investigation tested the hypothesis that the SGLT2 inhibitor empagliflozin (EMPA) affects cardiomyocyte electrical activity under hypoxic conditions. Rat neonatal and human induced pluripotent stem cell (iPSC)-derived cardiomyocytes incubated or not with the hypoxia-mimetic agent CoCl2 were treated with EMPA (1 μM) or vehicle for 24 h. Action potential records obtained using intracellular microelectrodes demonstrated that EMPA reduced the action potential duration at 30%, 50%, and 90% repolarization and arrhythmogenic events in rat and human cardiomyocytes under normoxia and hypoxia. Analysis of Ca2+ transients using Fura-2-AM and contractility kinetics showed that EMPA increased Ca2+ transient amplitude and decreased the half-time to recover Ca2+ transients and relaxation time in rat neonatal cardiomyocytes. We also observed that the combination of EMPA with the Na+/H+ exchanger isoform 1 (NHE1) inhibitor cariporide (10 µM) exerted a more pronounced effect on Ca2+ transients and contractility than either EMPA or cariporide alone. Besides, EMPA, but not cariporide, increased phospholamban phosphorylation at serine 16. Collectively, our data reveal that EMPA reduces arrhythmogenic events, decreases the action potential duration in rat neonatal and human cardiomyocytes under normoxic or hypoxic conditions, and improves cytosolic calcium handling at least partially independent of NHE1. Moreover, we provided further evidence that SGLT2 inhibitor-mediated cardioprotection may be partly attributed to its cardiomyocyte electrophysiological effects.
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Affiliation(s)
- Danúbia Silva Dos Santos
- Laboratório de Genética e Cardiologia Molecular, Faculdade de Medicina, Instituto do Coração (InCor), Hospital das Clínicas HCFMUSP, Universidade de São Paulo, Avenida Dr. Enéas de Carvalho Aguiar, 44 - Bloco II 10° Andar, São Paulo, 05403-900, Brazil
| | - Lauro Thiago Turaça
- Laboratório de Genética e Cardiologia Molecular, Faculdade de Medicina, Instituto do Coração (InCor), Hospital das Clínicas HCFMUSP, Universidade de São Paulo, Avenida Dr. Enéas de Carvalho Aguiar, 44 - Bloco II 10° Andar, São Paulo, 05403-900, Brazil
| | | | - Raiana Andrade Quintanilha Barbosa
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Centro de Tecnologia Celular, Instituto Nacional de Cardiologia, Rio de Janeiro, Brazil
| | - Juliano Zequini Polidoro
- Laboratório de Genética e Cardiologia Molecular, Faculdade de Medicina, Instituto do Coração (InCor), Hospital das Clínicas HCFMUSP, Universidade de São Paulo, Avenida Dr. Enéas de Carvalho Aguiar, 44 - Bloco II 10° Andar, São Paulo, 05403-900, Brazil
| | - Tais Hanae Kasai-Brunswick
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Centro Nacional de Biologia Estrutural e Bioimagem (CENABIO), Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Antonio Carlos Campos de Carvalho
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
- Centro Nacional de Biologia Estrutural e Bioimagem (CENABIO), Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Adriana Castello Costa Girardi
- Laboratório de Genética e Cardiologia Molecular, Faculdade de Medicina, Instituto do Coração (InCor), Hospital das Clínicas HCFMUSP, Universidade de São Paulo, Avenida Dr. Enéas de Carvalho Aguiar, 44 - Bloco II 10° Andar, São Paulo, 05403-900, Brazil.
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4
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Oshiyama NF, Pereira AHM, Cardoso AC, Franchini KG, Bassani JWM, Bassani RA. Developmental differences in myocardial transmembrane Na + transport: Implications for excitability and Na + handling. J Physiol 2022; 600:2651-2667. [PMID: 35489088 DOI: 10.1113/jp282661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 04/20/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Previous studies showed that myocardial preparations from immature rats are less sensitive to electrical field stimulation than adult preparations. Freshly-isolated ventricular myocytes from neonatal rats showed lower excitability than adult cells, e.g., less negative threshold membrane potential and greater membrane depolarization required for action potential triggering. In addition to differences in mRNA levels for Na+ channels isoforms and greater Na+ current (INa ) density, Na+ channel voltage-dependence was shifted to the right in immature myocytes, which seems to be sufficient to decrease excitability, according to computer simulations. Only in neonatal myocytes did cyclic activity promote marked cytosolic Na+ accumulation, which was prevented by abolition of systolic Ca2+ transients by blockade of Ca2+ currents. Developmental changes in INa may account for the difference in action potential initiation parameters, but not for cytosolic Na+ accumulation, which seems to be due mainly to Na+ /Ca2+ exchanger-mediated Na+ influx. ABSTRACT Little is currently known about possible developmental changes in myocardial Na+ handling, which may have impact on cell excitability and Ca2+ content. Resting intracellular Na+ concentration ([Na+ ]i ), measured in freshly-isolated rat ventricular myocytes with CoroNa-green, was not significantly different in neonates (3-5 days old) and adults, but electrical stimulation caused marked [Na+ ]i rise only in neonates. Inhibition of L-type Ca2+ current by CdCl2 abolished not only systolic Ca2+ transients, but also activity-dependent intracellular Na+ accumulation in immature cells. This indicates that the main Na+ influx pathway during activity is the Na+ /Ca2+ exchanger, rather than voltage-dependent Na+ current (INa ), which was not affected by CdCl2 . In immature myocytes, INa density was 2-fold greater, inactivation was faster, and the current peak occurred at less negative transmembrane potential (Em ) than in adults. Na+ channel steady-state activation and inactivation curves in neonates showed a rightward shift, which should increase channel availability at diastolic Em , but also require greater depolarization for excitation, which was observed experimentally and reproduced in computer simulations. Ventricular mRNA levels of Nav 1.1, Nav 1.4 and Nav 1.5 pore-forming isoforms were greater in neonate ventricles, while decrease was seen for the β1 subunit. Both molecular and biophysical changes in the channel profile may contribute to the differences in INa density and voltage-dependence, and also to the less negative threshold Em in neonates, compared to adults. The apparently lower excitability in immature ventricle may confer protection against the development of spontaneous activity in this tissue. Abstract figure legend Little is currently known about possible developmental changes in myocardial Na+ transport, which may have impact on cell excitability and other physiological aspects. At the mRNA level, neonatal rat ventricle expresses a greater variety of Na+ channel isoforms than in adults. In immature ventricular cardiomyocytes, Na+ current (INa ) density was greater, but voltage-dependence is shifted to less negative potentials than in adults. This should increase channel availability at diastolic membrane potential, but also require greater depolarization for excitation, which was observed experimentally and reproduced in computer simulation. We also observed that electrical stimulation caused marked intracellular Na+ accumulation only in neonates, which was abolished when Ca2+ transients and the Na+ /Ca2+ exchanger (NCX) were inhibited by Cd2+ + Ni2+ . Thus, it seems that the main Na+ influx pathway during activity in neonates is the NCX, rather than voltage-dependent INa , which was not affected by these blockers. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Natália F Oshiyama
- Department of Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Campinas, SP, Brazil.,National Laboratory for Cell Calcium Study, (LabNECC), Center for Biomedical Engineering, University of Campinas, Campinas, SP, Brazil
| | - Ana H M Pereira
- Brazilian Biosciences National Laboratory, Brazilian Center for Research in Energy and Materials (LNBio/CNPEM), Campinas, SP, Brazil
| | - Alisson C Cardoso
- Brazilian Biosciences National Laboratory, Brazilian Center for Research in Energy and Materials (LNBio/CNPEM), Campinas, SP, Brazil
| | - Kleber G Franchini
- Brazilian Biosciences National Laboratory, Brazilian Center for Research in Energy and Materials (LNBio/CNPEM), Campinas, SP, Brazil.,Department of Internal Medicine, School of Medicine, University of Campinas, Campinas, SP, Brazil
| | - José W M Bassani
- Department of Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Campinas, SP, Brazil.,National Laboratory for Cell Calcium Study, (LabNECC), Center for Biomedical Engineering, University of Campinas, Campinas, SP, Brazil
| | - Rosana A Bassani
- Department of Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Campinas, SP, Brazil.,National Laboratory for Cell Calcium Study, (LabNECC), Center for Biomedical Engineering, University of Campinas, Campinas, SP, Brazil
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5
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Hager NA, McAtee CK, Lesko MA, O’Donnell AF. Inwardly Rectifying Potassium Channel Kir2.1 and its "Kir-ious" Regulation by Protein Trafficking and Roles in Development and Disease. Front Cell Dev Biol 2022; 9:796136. [PMID: 35223865 PMCID: PMC8864065 DOI: 10.3389/fcell.2021.796136] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 12/15/2021] [Indexed: 11/13/2022] Open
Abstract
Potassium (K+) homeostasis is tightly regulated for optimal cell and organismal health. Failure to control potassium balance results in disease, including cardiac arrythmias and developmental disorders. A family of inwardly rectifying potassium (Kir) channels helps cells maintain K+ levels. Encoded by KCNJ genes, Kir channels are comprised of a tetramer of Kir subunits, each of which contains two-transmembrane domains. The assembled Kir channel generates an ion selectivity filter for K+ at the monomer interface, which allows for K+ transit. Kir channels are found in many cell types and influence K+ homeostasis across the organism, impacting muscle, nerve and immune function. Kir2.1 is one of the best studied family members with well-defined roles in regulating heart rhythm, muscle contraction and bone development. Due to their expansive roles, it is not surprising that Kir mutations lead to disease, including cardiomyopathies, and neurological and metabolic disorders. Kir malfunction is linked to developmental defects, including underdeveloped skeletal systems and cerebellar abnormalities. Mutations in Kir2.1 cause the periodic paralysis, cardiac arrythmia, and developmental deficits associated with Andersen-Tawil Syndrome. Here we review the roles of Kir family member Kir2.1 in maintaining K+ balance with a specific focus on our understanding of Kir2.1 channel trafficking and emerging roles in development and disease. We provide a synopsis of the vital work focused on understanding the trafficking of Kir2.1 and its role in development.
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Affiliation(s)
| | | | | | - Allyson F. O’Donnell
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, United States
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6
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Liao Y, Zhu L, Wang Y. Maturation of Stem Cell-Derived Cardiomyocytes: Foe in Translation Medicine. Int J Stem Cells 2021; 14:366-385. [PMID: 34711701 PMCID: PMC8611306 DOI: 10.15283/ijsc21077] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 07/16/2021] [Accepted: 08/23/2021] [Indexed: 11/17/2022] Open
Abstract
With the in-depth study of heart development, many human cardiomyocytes (CMs) have been generated in a laboratory environment. CMs derived from pluripotent stem cells (PSCs) have been widely used for a series of applications such as laboratory studies, drug toxicology screening, cardiac disease models, and as an unlimited resource for cell-based cardiac regeneration therapy. However, the low maturity of the induced CMs significantly impedes their applicability. Scientists have been committed to improving the maturation of CMs to achieve the purpose of heart regeneration in the past decades. In this review, we take CMs maturation as the main object of discussion, describe the characteristics of CMs maturation, summarize the key regulatory mechanism of regulating maturation and address the approaches to promote CMs maturation. The maturation of CM is gradually improving due to the incorporation of advanced technologies and is expected to continue.
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Affiliation(s)
- Yingnan Liao
- Xiamen Key Laboratory of Cardiovascular Disease, Xiamen Cardiovascular Hospital, Xiamen University, Xiamen, China
| | - Liyuan Zhu
- Xiamen Key Laboratory of Cardiovascular Disease, Xiamen Cardiovascular Hospital, Xiamen University, Xiamen, China
| | - Yan Wang
- Xiamen Key Laboratory of Cardiovascular Disease, Xiamen Cardiovascular Hospital, Xiamen University, Xiamen, China
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7
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Baczkó I, Hornyik T, Brunner M, Koren G, Odening KE. Transgenic Rabbit Models in Proarrhythmia Research. Front Pharmacol 2020; 11:853. [PMID: 32581808 PMCID: PMC7291951 DOI: 10.3389/fphar.2020.00853] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 05/22/2020] [Indexed: 12/23/2022] Open
Abstract
Drug-induced proarrhythmia constitutes a potentially lethal side effect of various drugs. Most often, this proarrhythmia is mechanistically linked to the drug's potential to interact with repolarizing cardiac ion channels causing a prolongation of the QT interval in the ECG. Despite sophisticated screening approaches during drug development, reliable prediction of proarrhythmia remains very challenging. Although drug-induced long-QT-related proarrhythmia is often favored by conditions or diseases that impair the individual's repolarization reserve, most cellular, tissue, and whole animal model systems used for drug safety screening are based on normal, healthy models. In recent years, several transgenic rabbit models for different types of long QT syndromes (LQTS) with differences in the extent of impairment in repolarization reserve have been generated. These might be useful for screening/prediction of a drug's potential for long-QT-related proarrhythmia, particularly as different repolarizing cardiac ion channels are impaired in the different models. In this review, we summarize the electrophysiological characteristics of the available transgenic LQTS rabbit models, and the pharmacological proof-of-principle studies that have been performed with these models—highlighting the advantages and disadvantages of LQTS models for proarrhythmia research. In the end, we give an outlook on potential future directions and novel models.
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Affiliation(s)
- István Baczkó
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Tibor Hornyik
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary.,Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Michael Brunner
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Department of Cardiology and Medical Intensive Care, St. Josefskrankenhaus, Freiburg, Germany
| | - Gideon Koren
- Cardiovascular Research Center, Division of Cardiology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI, United States
| | - Katja E Odening
- Department of Cardiology and Angiology I, Heart Center, University of Freiburg, Freiburg, Germany.,Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Translational Cardiology, Department of Cardiology, Inselspital, Bern University Hospital, Bern, Switzerland.,Institute of Physiology, University of Bern, Bern, Switzerland
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8
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Lu A, Kamkar M, Chu C, Wang J, Gaudet K, Chen Y, Lin L, Liu W, Marbán E, Liang W. Direct and Indirect Suppression of Scn5a Gene Expression Mediates Cardiac Na + Channel Inhibition by Wnt Signalling. Can J Cardiol 2020; 36:564-576. [PMID: 32046907 DOI: 10.1016/j.cjca.2019.09.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 09/10/2019] [Accepted: 09/26/2019] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Myocardial infarction and heart failure are associated with reduced voltage-gated Na+ current (INa) that promotes arrhythmias and sudden deaths. We have previously shown that the Wnt/β-catenin signalling (Wnt signalling), which is active in heart disease, reduces cardiac INa, suggesting that Wnt signalling may be a potential therapeutic target. However, because Wnt signalling is required for the homeostasis of many noncardiac tissues, administration of Wnt inhibitors to heart patients would cause significant side effects. The present study aims to elucidate the molecular mechanisms of cardiac INa inhibition by Wnt, which would identify cardiac-specific therapeutic targets. METHODS Wnt signalling was activated in neonatal rat ventricular myocytes by Wnt3a protein. Adenovirus expressing Wnt3a was injected into the adult rat ventricle. CRISPR/Cas9 and chromatin immunoprecipitation were used for mechanistic studies. RESULTS Wnt signalling activation in neonatal rat ventricular myocytes reduced Nav1.5 protein and Scn5a mRNA, but increased Tbx3, a known suppressor of Scn5a. Chromatin immunoprecipitation showed that Wnt signalling inhibits Scn5a expression through downstream mediator (TCF4) binding to both Tbx3 and Scn5a promoters. Overexpression or knockdown of Tbx3 directly modified Nav1.5 and INa, whereas CRISPR/Cas9-induced mutations at TCF4 binding sites within the Scn5a promoter attenuated Wnt inhibition of Scn5a and Nav1.5. In adult rat hearts, adenovirus expressing Wnt3a reduced Nav1.5, increased QRS duration in electrocardiogram, and increased the susceptibility to ventricular tachycardia. CONCLUSIONS Wnt signalling inhibits the Na+ channel by direct and indirect (via Tbx3) suppression of Scn5a transcription. Strategies to block TCF4 binding to the Tbx3 and Scn5a promoters would represent novel strategies for cardiac-specific inhibition of the Wnt pathway to rescue INa and prevent sudden cardiac deaths.
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Affiliation(s)
- Aizhu Lu
- University of Ottawa Heart Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Maryam Kamkar
- University of Ottawa Heart Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Cencen Chu
- University of Ottawa Heart Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Jerry Wang
- University of Ottawa Heart Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Kaya Gaudet
- University of Ottawa Heart Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Yawen Chen
- University of Ottawa Heart Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Lauren Lin
- University of Ottawa Heart Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Weixin Liu
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Eduardo Marbán
- Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Wenbin Liang
- University of Ottawa Heart Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada.
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9
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Swift LM, Burke M, Guerrelli D, Reilly M, Ramadan M, McCullough D, Prudencio T, Mulvany C, Chaluvadi A, Jaimes R, Posnack NG. Age-dependent changes in electrophysiology and calcium handling: implications for pediatric cardiac research. Am J Physiol Heart Circ Physiol 2019; 318:H354-H365. [PMID: 31886723 DOI: 10.1152/ajpheart.00521.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Rodent models are frequently employed in cardiovascular research, yet our understanding of pediatric cardiac physiology has largely been deduced from more simplified two-dimensional cell studies. Previous studies have shown that postnatal development includes an alteration in the expression of genes and proteins involved in cell coupling, ion channels, and intracellular calcium handling. Accordingly, we hypothesized that postnatal cell maturation is likely to lead to dynamic alterations in whole heart electrophysiology and calcium handling. To test this hypothesis, we employed multiparametric imaging and electrophysiological techniques to quantify developmental changes from neonate to adult. In vivo electrocardiograms were collected to assess changes in heart rate, variability, and atrioventricular conduction (Sprague-Dawley rats). Intact, whole hearts were transferred to a Langendorff-perfusion system for multiparametric imaging (voltage, calcium). Optical mapping was performed in conjunction with an electrophysiology study to assess cardiac dynamics throughout development. Postnatal age was associated with an increase in the heart rate (181 ± 34 vs. 429 ± 13 beats/min), faster atrioventricular conduction (94 ± 13 vs. 46 ± 3 ms), shortened action potentials (APD80: 113 ± 18 vs. 60 ± 17 ms), and decreased ventricular refractoriness (VERP: 157 ± 45 vs. 57 ± 14 ms; neonatal vs. adults, means ± SD, P < 0.05). Calcium handling matured with development, resulting in shortened calcium transient durations (168 ± 18 vs. 117 ± 14 ms) and decreased propensity for calcium transient alternans (160 ± 18- vs. 99 ± 11-ms cycle length threshold; neonatal vs. adults, mean ± SD, P < 0.05). Results of this study can serve as a comprehensive baseline for future studies focused on pediatric disease modeling and/or preclinical testing.NEW & NOTEWORTHY This is the first study to assess cardiac electrophysiology and calcium handling throughout postnatal development, using both in vivo and whole heart models.
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Affiliation(s)
- Luther M Swift
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Health System, Washington, District of Columbia.,Children's National Heart Institute, Children's National Health System, Washington, District of Columbia
| | - Morgan Burke
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Health System, Washington, District of Columbia.,Children's National Heart Institute, Children's National Health System, Washington, District of Columbia
| | - Devon Guerrelli
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Health System, Washington, District of Columbia.,Children's National Heart Institute, Children's National Health System, Washington, District of Columbia
| | - Marissa Reilly
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Health System, Washington, District of Columbia
| | - Manelle Ramadan
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Health System, Washington, District of Columbia.,Children's National Heart Institute, Children's National Health System, Washington, District of Columbia
| | - Damon McCullough
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Health System, Washington, District of Columbia.,Children's National Heart Institute, Children's National Health System, Washington, District of Columbia
| | - Tomas Prudencio
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Health System, Washington, District of Columbia
| | - Colm Mulvany
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Health System, Washington, District of Columbia
| | - Ashika Chaluvadi
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Health System, Washington, District of Columbia
| | - Rafael Jaimes
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Health System, Washington, District of Columbia.,Children's National Heart Institute, Children's National Health System, Washington, District of Columbia
| | - Nikki Gillum Posnack
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Health System, Washington, District of Columbia.,Children's National Heart Institute, Children's National Health System, Washington, District of Columbia.,Department of Pediatrics and Department of Pharmacology and Physiology, School of Medicine and Health Sciences, George Washington University, Washington, District of Columbia
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10
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Reduced hybrid/complex N-glycosylation disrupts cardiac electrical signaling and calcium handling in a model of dilated cardiomyopathy. J Mol Cell Cardiol 2019; 132:13-23. [PMID: 31071333 DOI: 10.1016/j.yjmcc.2019.05.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 04/12/2019] [Accepted: 05/01/2019] [Indexed: 12/19/2022]
Abstract
Dilated cardiomyopathy (DCM) is the third most common cause of heart failure, with ~70% of DCM cases considered idiopathic. We showed recently, through genetic ablation of the MGAT1 gene, which encodes an essential glycosyltransferase (GlcNAcT1), that prevention of cardiomyocyte hybrid/complex N-glycosylation was sufficient to cause DCM that led to heart failure and early death. Our findings are consistent with increasing evidence suggesting a link between aberrant glycosylation and heart diseases of acquired and congenital etiologies. However, the mechanisms by which changes in glycosylation contribute to disease onset and progression remain largely unknown. Activity and gating of voltage-gated Na+ and K+ channels (Nav and Kv respectively) play pivotal roles in the initiation, shaping and conduction of cardiomyocyte action potentials (APs) and aberrant channel activity was shown to contribute to cardiac disease. We and others showed that glycosylation can impact Nav and Kv function; therefore, here, we investigated the effects of reduced cardiomyocyte hybrid/complex N-glycosylation on channel activity to investigate whether chronic aberrant channel function can contribute to DCM. Ventricular cardiomyocytes from MGAT1 deficient (MGAT1KO) mice display prolonged APs and pacing-induced aberrant early re-activation that can be attributed to, at least in part, a significant reduction in Kv expression and activity that worsens over time suggesting heart disease-related remodeling. MGAT1KO Nav demonstrate no change in expression or maximal conductance but show depolarizing shifts in voltage-dependent gating. Together, the changes in MGAT1KO Nav and Kv function likely contribute to observed anomalous electrocardiograms and Ca2+ handling. These findings provide insight into mechanisms by which altered glycosylation contributes to DCM through changes in Nav and Kv activity that impact conduction, Ca2+ handling and contraction. The MGAT1KO can also serve as a useful model to study the effects of aberrant electrical signaling on cardiac function and the remodeling events that can occur with heart disease progression.
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11
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Jackman C, Li H, Bursac N. Long-term contractile activity and thyroid hormone supplementation produce engineered rat myocardium with adult-like structure and function. Acta Biomater 2018; 78:98-110. [PMID: 30086384 DOI: 10.1016/j.actbio.2018.08.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 08/02/2018] [Accepted: 08/03/2018] [Indexed: 02/07/2023]
Abstract
The field of cardiac tissue engineering has developed rapidly, but structural and functional immaturity of engineered heart tissues hinder their widespread use. Here, we show that a combination of low-rate (0.2 Hz) contractile activity and thyroid hormone (T3) supplementation significantly promote structural and functional maturation of engineered rat cardiac tissues ("cardiobundles"). The progressive maturation of cardiobundles during first 2 weeks of culture resulted in cell cycle exit and loss of spontaneous activity, which in longer culture yielded decreased contractile function. Maintaining a low level of contractile activity by 0.2 Hz pacing between culture weeks 3 and 5, combined with T3 treatment, yielded significant growth of cardiobundle and myocyte cross-sectional areas (by 68% and 32%, respectively), increased nuclei numbers (by 22%), improved twitch force (by 39%), shortened action potential duration (by 32%), polarized N-cadherin distribution, and switch from immature (slow skeletal) to mature (fast) cardiac troponin I isoform expression. Along with advanced functional output (conduction velocity 53.7 ± 0.8 cm/s, specific force 70.1 ± 5.8 mN/mm2), quantitative ultrastructural analyses revealed similar metrics and abundance of sarcomeres, T-tubules, M-bands, and intercalated disks compared to native age-matched (5-week) and adult (3-month) ventricular myocytes. Unlike 0.2 Hz regime, chronic 1 Hz pacing resulted in significant cardiomyocyte loss and formation of necrotic core despite the use of dynamic culture. Overall, our results demonstrate remarkable ultrastructural and functional maturation of neonatal rat cardiomyocytes in 3D culture and reveal importance of combined biophysical and hormonal inputs for in vitro engineering of adult-like myocardium. STATEMENT OF SIGNIFICANCE Compared to human stem cell-derived cardiomyocytes, neonatal rat ventricular myocytes show advanced maturation state which makes them suitable for in vitro studies of postnatal cardiac development. Still, maturation process from a neonatal to an adult cardiomyocyte has not been recapitulated in rodent cell cultures. Here, we show that low-frequency pacing and thyroid hormone supplementation of 3D engineered neonatal rat cardiac tissues synergistically yield significant increase in cell and tissue volume, robust formation of T-tubules and M-lines, improved sarcomere organization, and faster and more forceful contractions. To the best of our knowledge, 5-week old engineered cardiac tissues described in this study are the first that exhibit both ultrastructural and functional characteristics approaching or matching those of adult ventricular myocardium.
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12
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Sagawa H, Hoshino S, Yoshioka K, Ding WG, Omatsu-Kanbe M, Nakagawa M, Maruo Y, Matsuura H. Postnatal developmental changes in the sensitivity of L-type Ca 2+ channel to inhibition by verapamil in a mouse heart model. Pediatr Res 2018; 83:1207-1217. [PMID: 29554082 DOI: 10.1038/pr.2018.46] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 01/29/2018] [Indexed: 11/09/2022]
Abstract
BackgroundIn the clinical setting, verapamil is contraindicated in neonates and infants, because of the perceived risk of hypotension or bradyarrhythmia. However, it remains unclear whether there is an age-dependent difference in the sensitivity of cardiac L-type Ca2+ channel current (ICa,L) to inhibition by verapamil.MethodsVentricular myocytes were enzymatically dissociated from the hearts of six different age groups (0, 7, 14, 21, 28 days, and 10-15 weeks) of mice, using a similar Langendorff-perfusion method. Whole-cell patch-clamp technique was applied to examine the sensitivity of ICa,L to inhibition, by three classes of structurally different L-type Ca2+ channel antagonists.ResultsVerapamil, nifedipine, and diltiazem concentration-dependently blocked the ventricular ICa,L in all six age groups. However, although nifedipine and diltiazem blocked ventricular ICa,L with a similar potency in all age groups, verapamil more potently blocked ventricular ICa,L in day 0, day 7, day 14, and day 21 mice, than in day 28, and 10-15-week mice.ConclusionIn a mouse heart model, ventricular ICa,L before the weaning age (~21 days of age) exhibited a higher sensitivity to inhibition by verapamil than that after the weaning age, which may explain one possible mechanism associated with the development of verapamil-induced hypotension in human neonates and infants.
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Affiliation(s)
- Hironori Sagawa
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Shinsuke Hoshino
- Department of Pediatrics, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Kengo Yoshioka
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Wei-Guang Ding
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Mariko Omatsu-Kanbe
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Masao Nakagawa
- Department of Pediatrics, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Yoshihiro Maruo
- Department of Pediatrics, Shiga University of Medical Science, Otsu, Shiga, Japan
| | - Hiroshi Matsuura
- Department of Physiology, Shiga University of Medical Science, Otsu, Shiga, Japan
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13
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Borghetti G, Eisenberg CA, Signore S, Sorrentino A, Kaur K, Andrade-Vicenty A, Edwards JG, Nerkar M, Qanud K, Sun D, Goichberg P, Leri A, Anversa P, Eisenberg LM, Jacobson JT, Hintze TH, Rota M. Notch signaling modulates the electrical behavior of cardiomyocytes. Am J Physiol Heart Circ Physiol 2017; 314:H68-H81. [PMID: 28939651 DOI: 10.1152/ajpheart.00587.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Notch receptor signaling is active during cardiac development and silenced in myocytes after birth. Conversely, outward K+ Kv currents progressively appear in postnatal myocytes leading to shortening of the action potential (AP) and acquisition of the mature electrical phenotype. In the present study, we tested the possibility that Notch signaling modulates the electrical behavior of cardiomyocytes by interfering with Kv currents. For this purpose, the effects of Notch receptor activity on electrophysiological properties of myocytes were evaluated using transgenic mice with inducible expression of the Notch1 intracellular domain (NICD), the functional fragment of the activated Notch receptor, and in neonatal myocytes after inhibition of the Notch transduction pathway. By patch clamp, NICD-overexpressing cells presented prolonged AP duration and reduced upstroke amplitude, properties that were coupled with reduced rapidly activating Kv and fast Na+ currents, compared with cells obtained from wild-type mice. In cultured neonatal myocytes, inhibition of the proteolitic release of NICD with a γ-secretase antagonist increased transcript levels of the Kv channel-interacting proteins 2 (KChIP2) and enhanced the density of Kv currents. Collectively, these results indicate that Notch signaling represents an important regulator of the electrophysiological behavior of developing and adult myocytes by repressing, at least in part, repolarizing Kv currents. NEW & NOTEWORTHY We investigated the effects of Notch receptor signaling on the electrical properties of cardiomyocytes. Our results indicate that the Notch transduction pathway interferes with outward K+ Kv currents, critical determinants of the electrical repolarization of myocytes.
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Affiliation(s)
- Giulia Borghetti
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
| | - Carol A Eisenberg
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Sergio Signore
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
| | - Andrea Sorrentino
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
| | - Keerat Kaur
- Department of Physiology, New York Medical College, Valhalla, New York
| | | | - John G Edwards
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Mriganka Nerkar
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Khaled Qanud
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Dong Sun
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Polina Goichberg
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
| | - Annarosa Leri
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
| | - Piero Anversa
- Departments of Anesthesia and Medicine, and Division of Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School , Boston, Massachusetts
| | | | - Jason T Jacobson
- Department of Physiology, New York Medical College, Valhalla, New York.,Department of Cardiology, Westchester Medical Center, Valhalla, New York
| | - Thomas H Hintze
- Department of Physiology, New York Medical College, Valhalla, New York
| | - Marcello Rota
- Department of Physiology, New York Medical College, Valhalla, New York
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14
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Peinkofer G, Burkert K, Urban K, Krausgrill B, Hescheler J, Saric T, Halbach M. From Early Embryonic to Adult Stage: Comparative Study of Action Potentials of Native and Pluripotent Stem Cell-Derived Cardiomyocytes. Stem Cells Dev 2016; 25:1397-406. [DOI: 10.1089/scd.2016.0073] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Affiliation(s)
- Gabriel Peinkofer
- Department of Internal Medicine III, University of Cologne, Cologne, Germany
- Institute of Neurophysiology, University of Cologne, Cologne, Germany
| | - Karsten Burkert
- Institute of Neurophysiology, University of Cologne, Cologne, Germany
| | - Katja Urban
- Department of Internal Medicine III, University of Cologne, Cologne, Germany
| | - Benjamin Krausgrill
- Department of Internal Medicine III, University of Cologne, Cologne, Germany
| | - Jürgen Hescheler
- Institute of Neurophysiology, University of Cologne, Cologne, Germany
| | - Tomo Saric
- Institute of Neurophysiology, University of Cologne, Cologne, Germany
| | - Marcel Halbach
- Department of Internal Medicine III, University of Cologne, Cologne, Germany
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15
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Baczkó I, Jost N, Virág L, Bősze Z, Varró A. Rabbit models as tools for preclinical cardiac electrophysiological safety testing: Importance of repolarization reserve. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 121:157-68. [PMID: 27208697 DOI: 10.1016/j.pbiomolbio.2016.05.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 05/01/2016] [Indexed: 01/26/2023]
Abstract
It is essential to more reliably assess the pro-arrhythmic liability of compounds in development. Current guidelines for pre-clinical and clinical testing of drug candidates advocate the use of healthy animals/tissues and healthy individuals and focus on the test compound's ability to block the hERG current and prolong cardiac ventricular repolarization. Also, pre-clinical safety tests utilize several species commonly used in cardiac electrophysiological studies. In this review, important species differences in cardiac ventricular repolarizing ion currents are considered, followed by the discussion on electrical remodeling associated with chronic cardiovascular diseases that leads to altered ion channel and transporter expression and densities in pathological settings. We argue that the choice of species strongly influences experimental outcome and extrapolation of results to human clinical settings. We suggest that based on cardiac cellular electrophysiology, the rabbit is a useful species for pharmacological pro-arrhythmic investigations. In addition to healthy animals and tissues, the use of animal models (e.g. those with impaired repolarization reserve) is suggested that more closely resemble subsets of patients exhibiting increased vulnerability towards the development of ventricular arrhythmias and sudden cardiac death.
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Affiliation(s)
- István Baczkó
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Dóm tér 12., 6720 Szeged, Hungary.
| | - Norbert Jost
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Dóm tér 12., 6720 Szeged, Hungary; MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Dóm tér 12., 6720 Szeged, Hungary
| | - László Virág
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Dóm tér 12., 6720 Szeged, Hungary
| | - Zsuzsanna Bősze
- Rabbit Genome and Biomodel Group, NARIC-Agricultural Biotechnology Institute, 2100 Gödöllő, Hungary
| | - András Varró
- Department of Pharmacology & Pharmacotherapy, University of Szeged, Dóm tér 12., 6720 Szeged, Hungary; MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Dóm tér 12., 6720 Szeged, Hungary
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16
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Tétreault MP, Bourdin B, Briot J, Segura E, Lesage S, Fiset C, Parent L. Identification of Glycosylation Sites Essential for Surface Expression of the CaVα2δ1 Subunit and Modulation of the Cardiac CaV1.2 Channel Activity. J Biol Chem 2016; 291:4826-43. [PMID: 26742847 DOI: 10.1074/jbc.m115.692178] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Indexed: 12/15/2022] Open
Abstract
Alteration in the L-type current density is one aspect of the electrical remodeling observed in patients suffering from cardiac arrhythmias. Changes in channel function could result from variations in the protein biogenesis, stability, post-translational modification, and/or trafficking in any of the regulatory subunits forming cardiac L-type Ca(2+) channel complexes. CaVα2δ1 is potentially the most heavily N-glycosylated subunit in the cardiac L-type CaV1.2 channel complex. Here, we show that enzymatic removal of N-glycans produced a 50-kDa shift in the mobility of cardiac and recombinant CaVα2δ1 proteins. This change was also observed upon simultaneous mutation of the 16 Asn sites. Nonetheless, the mutation of only 6/16 sites was sufficient to significantly 1) reduce the steady-state cell surface fluorescence of CaVα2δ1 as characterized by two-color flow cytometry assays and confocal imaging; 2) decrease protein stability estimated from cycloheximide chase assays; and 3) prevent the CaVα2δ1-mediated increase in the peak current density and voltage-dependent gating of CaV1.2. Reversing the N348Q and N812Q mutations in the non-operational sextuplet Asn mutant protein partially restored CaVα2δ1 function. Single mutation N663Q and double mutations N348Q/N468Q, N348Q/N812Q, and N468Q/N812Q decreased protein stability/synthesis and nearly abolished steady-state cell surface density of CaVα2δ1 as well as the CaVα2δ1-induced up-regulation of L-type currents. These results demonstrate that Asn-663 and to a lesser extent Asn-348, Asn-468, and Asn-812 contribute to protein stability/synthesis of CaVα2δ1, and furthermore that N-glycosylation of CaVα2δ1 is essential to produce functional L-type Ca(2+) channels.
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Affiliation(s)
| | - Benoîte Bourdin
- From the Départment de Physiologie Moléculaire et Intégrative, Faculté de Médecine, and
| | - Julie Briot
- From the Départment de Physiologie Moléculaire et Intégrative, Faculté de Médecine, and
| | - Emilie Segura
- From the Départment de Physiologie Moléculaire et Intégrative, Faculté de Médecine, and
| | - Sylvie Lesage
- Départment de Microbiologie, Infectiologie, and Immunologie, Faculté de Médecine, Centre de Recherche de l'Hôpital Maisonneuve-Rosemont, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Céline Fiset
- Faculté de Pharmacie, Institut de Cardiologie de Montréal and
| | - Lucie Parent
- From the Départment de Physiologie Moléculaire et Intégrative, Faculté de Médecine, and
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17
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El Khoury N, Mathieu S, Fiset C. Interleukin-1β reduces L-type Ca2+ current through protein kinase Cϵ activation in mouse heart. J Biol Chem 2014; 289:21896-908. [PMID: 24936064 DOI: 10.1074/jbc.m114.549642] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Inflammation is now widely recognized as a key component of heart disease. Patients suffering from arrhythmias and heart failure have increased levels of tumor necrosis factor-α (TNFα) and interleukin-1β (IL-1β). Evidence suggests that these cytokines are important mediators of cardiac remodeling; however, their effects on ion channels and arrhythmogenesis remain incompletely understood. The L-type Ca(2+) current (ICaL) is a major determinant of the plateau phase of cardiac action potential and has a critical excitation-contraction coupling role. Thus, altering its properties could have detrimental effects on cardiac electrical and contractile functions. Accordingly, the objective of this study was to elucidate the effect of TNFα and IL-1β on ICaL, while exploring the underlying regulatory mechanisms. Neonatal mouse ventricular myocytes were treated with a pathophysiological concentration (30 pg/ml) of TNFα and IL-1β for 24 h. Voltage-clamp recordings showed that TNFα had no effect on ICaL, whereas IL-1β decreased the current density by 36%. Although both IL-1β- and TNFα-treated myocytes showed significant increase in reactive oxidative species (ROS), Western blot experiments revealed that only IL-1β increased PKCϵ membrane translocation. The antioxidant N-acetyl-L-cysteine normalized ROS levels and restored ICaL density. Furthermore, the PKCϵ translocation inhibitor ϵ-V1-2 blocked the effect of IL-1β on ICaL. The reduction of ICaL by IL-1β was also seen in cultured adult ventricular myocytes. Overall, chronic IL-1β treatment decreased ICaL density in cardiomyocytes. These effects implicated ROS signaling and PKCϵ activation. These findings could contribute to explain the role of IL-1β in the development of arrhythmia and heart failure.
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Affiliation(s)
- Nabil El Khoury
- From the Research Center, Montreal Heart Institute, 5000 Bélanger, Montréal, Québec H1T 1C8, the Department of Physiology, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Sophie Mathieu
- From the Research Center, Montreal Heart Institute, 5000 Bélanger, Montréal, Québec H1T 1C8, the Faculty of Pharmacy, Université de Montréal, Montréal, Québec, and
| | - Céline Fiset
- From the Research Center, Montreal Heart Institute, 5000 Bélanger, Montréal, Québec H1T 1C8, the Faculty of Pharmacy, Université de Montréal, Montréal, Québec, and
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18
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Baumgartner S, Halbach M, Krausgrill B, Maass M, Srinivasan SP, Sahito RGA, Peinkofer G, Nguemo F, Müller-Ehmsen J, Hescheler J. Electrophysiological and morphological maturation of murine fetal cardiomyocytes during electrical stimulation in vitro. J Cardiovasc Pharmacol Ther 2014; 20:104-12. [PMID: 24917562 DOI: 10.1177/1074248414536273] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The aim of this study was to investigate whether continuous electrical stimulation affects electrophysiological properties and cell morphology of fetal cardiomyocytes (FCMs) in culture. Fetal cardiomyocytes at day 14.5 post coitum were harvested from murine hearts and electrically stimulated for 6 days in culture using a custom-made stimulation chamber. Subsequently, action potentials of FCM were recorded with glass microelectrodes. Immunostainings of α-Actinin, connexin 43, and vinculin were performed. Expression of ion channel subunits Kcnd2, Slc8a1, Cacna1, Kcnh2, and Kcnb1 was analyzed by quantitative reverse-transcriptase polymerase chain reaction. Action potential duration to 50% and 90% repolarization (APD50 and APD90) of electrically stimulated FCMs were significantly decreased when compared to nonstimulated control FCM. Alignment of cells was significantly higher in stimulated FCM when compared to control FCM. The expression of connexin 43 was significantly increased in stimulated FCM when compared to control FCM. The ratio between cell length and cell width of the stimulated FCM was significantly higher than in control FCM. Kcnh2 and Kcnd2 were upregulated in stimulated FCM when compared to control FCM. Expression of Slc8a1, Cacna1c, and Kcnb1 was not different in stimulated and control FCMs. The decrease in APD50 observed after electrical stimulation of FCM in vitro corresponds to the electrophysiological maturation of FCM in vivo. Expression levels of ion channels suggest that some important but not all aspects of the complex process of electrophysiological maturation are promoted by electrical stimulation. Parallel alignment, increased connexin 43 expression, and elongation of FCM are signs of a morphological maturation induced by electrical stimulation.
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Affiliation(s)
- Sven Baumgartner
- Department of Internal Medicine III-Cardiology, University of Cologne, Cologne, Germany Institute of Neurophysiology, University of Cologne, Cologne, Germany
| | - Marcel Halbach
- Department of Internal Medicine III-Cardiology, University of Cologne, Cologne, Germany Institute of Neurophysiology, University of Cologne, Cologne, Germany
| | - Benjamin Krausgrill
- Department of Internal Medicine III-Cardiology, University of Cologne, Cologne, Germany Institute of Neurophysiology, University of Cologne, Cologne, Germany
| | - Martina Maass
- Department of Internal Medicine III-Cardiology, University of Cologne, Cologne, Germany
| | | | | | - Gabriel Peinkofer
- Department of Internal Medicine III-Cardiology, University of Cologne, Cologne, Germany Institute of Neurophysiology, University of Cologne, Cologne, Germany
| | - Filomain Nguemo
- Institute of Neurophysiology, University of Cologne, Cologne, Germany
| | | | - Jürgen Hescheler
- Institute of Neurophysiology, University of Cologne, Cologne, Germany
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19
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El Khoury N, Mathieu S, Marger L, Ross J, El Gebeily G, Ethier N, Fiset C. Upregulation of the hyperpolarization-activated current increases pacemaker activity of the sinoatrial node and heart rate during pregnancy in mice. Circulation 2013; 127:2009-20. [PMID: 23609807 DOI: 10.1161/circulationaha.113.001689] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Pregnancy is associated with a faster heart rate (HR), which is a risk factor for arrhythmias. However, the underlying mechanisms for this increased HR are poorly understood. Therefore, this study was performed to gain mechanistic insight into the pregnancy-induced increase in HR. METHODS AND RESULTS Using surface ECG we observed that pregnant (P) mice have faster HR (531±14 beats per minute [bpm]) compared with nonpregnant (NP) mice (470±27 bpm; P<0.03). Results obtained with Langendorff-perfused hearts showed that this difference persisted in the absence of autonomic nervous innervation (NP, 327±16 bpm; P, 385±18 bpm; P<0.02). Spontaneous action potentials of sinoatrial node cells from pregnant mice exhibited higher automaticity (NP, 292±13 bpm; P, 330±12 bpm; P=0.047) and steeper diastolic depolarization (NP, 0.20±0.03 V/s; P, 0.40±0.06 V/s; P=0.004). Pregnancy increased the density of the hyperpolarization-activated current (If) (at -90mV: NP, -15.2±1.0 pA/pF; P, -28.6±2.9 pA/pF; P=0.0002) in sinoatrial node cells. Voltage dependence of the If activation curve and the intracellular cAMP levels were unchanged in sinoatrial node cells of pregnant mice. However, there was a significant increase in HCN2 channel protein expression with no change in HCN4 expression. Maximal depolarizing shift of the If activation curve induced by isoproterenol was attenuated in pregnancy. This reduced response to isoproterenol may be attributable to the lower cAMP sensitivity of HCN2 isoform compared with that of HCN4. CONCLUSIONS This study shows that an increase in If current density contributes to the acceleration of sinoatrial node automaticity and explains, in part, the higher HR observed in pregnancy.
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Affiliation(s)
- Nabil El Khoury
- Research Center, Montreal Heart Institute, 5000 Bélanger, Montréal, Québec, Canada, H1T 1C8
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20
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Yu L, Li M, She T, Shi C, Meng W, Wang B, Cheng M. Endothelin-1 stimulates the expression of L-type Ca2+ channels in neonatal rat cardiomyocytes via the extracellular signal-regulated kinase 1/2 pathway. J Membr Biol 2013; 246:343-53. [PMID: 23546014 DOI: 10.1007/s00232-013-9538-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2012] [Accepted: 03/16/2013] [Indexed: 01/07/2023]
Abstract
The cardiac L-type Ca(2+) channel current (I(Ca,L)) plays an important role in controlling both cardiac excitability and excitation-contraction coupling and is involved in the electrical remodeling during postnatal heart development and cardiac hypertrophy. However, the possible role of endothelin-1 (ET-1) in the electrical remodeling of postnatal and diseased hearts remains unclear. Therefore, the present study was designed to investigate the transcriptional regulation of I(Ca,L) mediated by ET-1 in neonatal rat ventricular myocytes using the whole-cell patch-clamp technique, quantitative RT-PCR and Western blotting. Furthermore, we determined whether the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway is involved. ET-1 increased I(Ca,L) density without altering its voltage dependence of activation and inactivation. In line with the absence of functional changes, ET-1 increased L-type Ca(2+) channel pore-forming α1C-subunit mRNA and protein levels without affecting the mRNA expression of auxiliary β- and α2/δ-subunits. Furthermore, an actinomycin D chase experiment revealed that ET-1 did not alter α1C-subunit mRNA stability. These effects of ET-1 were inhibited by the ETA receptor antagonist BQ-123 but not the ETB receptor antagonist BQ-788. Moreover, the effects of ET-1 on I(Ca,L) and α1C-subunit expression were abolished by the ERK1/2 inhibitor (PD98059) but not by the p38 MAPK inhibitor (SB203580) or the c-Jun N-terminal kinase inhibitor (SP600125). These findings indicate that ET-1 increased the transcription of L-type Ca(2+) channel in cardiomyocytes via activation of ERK1/2 through the ETA receptor, which may contribute to the electrical remodeling of heart during postnatal development and cardiac hypertrophy.
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Affiliation(s)
- Liangzhu Yu
- Hubei Province Key Laboratory on Cardiovascular, Cerebrovascular, and Metabolic Disorders, Hubei University of Science and Technology, Xianning, Peoples Republic of China.
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21
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Bot CT, Kherlopian AR, Ortega FA, Christini DJ, Krogh-Madsen T. Rapid genetic algorithm optimization of a mouse computational model: benefits for anthropomorphization of neonatal mouse cardiomyocytes. Front Physiol 2012; 3:421. [PMID: 23133423 PMCID: PMC3488799 DOI: 10.3389/fphys.2012.00421] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Accepted: 10/17/2012] [Indexed: 11/13/2022] Open
Abstract
While the mouse presents an invaluable experimental model organism in biology, its usefulness in cardiac arrhythmia research is limited in some aspects due to major electrophysiological differences between murine and human action potentials (APs). As previously described, these species-specific traits can be partly overcome by application of a cell-type transforming clamp (CTC) to anthropomorphize the murine cardiac AP. CTC is a hybrid experimental-computational dynamic clamp technique, in which a computationally calculated time-dependent current is inserted into a cell in real-time, to compensate for the differences between sarcolemmal currents of that cell (e.g., murine) and the desired species (e.g., human). For effective CTC performance, mismatch between the measured cell and a mathematical model used to mimic the measured AP must be minimal. We have developed a genetic algorithm (GA) approach that rapidly tunes a mathematical model to reproduce the AP of the murine cardiac myocyte under study. Compared to a prior implementation that used a template-based model selection approach, we show that GA optimization to a cell-specific model results in a much better recapitulation of the desired AP morphology with CTC. This improvement was more pronounced when anthropomorphizing neonatal mouse cardiomyocytes to human-like APs than to guinea pig APs. CTC may be useful for a wide range of applications, from screening effects of pharmaceutical compounds on ion channel activity, to exploring variations in the mouse or human genome. Rapid GA optimization of a cell-specific mathematical model improves CTC performance and may therefore expand the applicability and usage of the CTC technique.
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Affiliation(s)
- Corina T. Bot
- Greenberg Division of Cardiology, Weill Cornell Medical CollegeNew York, NY, USA
| | - Armen R. Kherlopian
- Greenberg Division of Cardiology, Weill Cornell Medical CollegeNew York, NY, USA
- Department of Physiology, Biophysics and Systems Biology, Weill Cornell Medical CollegeNew York, NY, USA
| | - Francis A. Ortega
- Greenberg Division of Cardiology, Weill Cornell Medical CollegeNew York, NY, USA
| | - David J. Christini
- Greenberg Division of Cardiology, Weill Cornell Medical CollegeNew York, NY, USA
- Department of Physiology, Biophysics and Systems Biology, Weill Cornell Medical CollegeNew York, NY, USA
- Institute for Computational Biomedicine, Weill Cornell Medical CollegeNew York, NY, USA
| | - Trine Krogh-Madsen
- Greenberg Division of Cardiology, Weill Cornell Medical CollegeNew York, NY, USA
- Institute for Computational Biomedicine, Weill Cornell Medical CollegeNew York, NY, USA
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22
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Kaese S, Verheule S. Cardiac electrophysiology in mice: a matter of size. Front Physiol 2012; 3:345. [PMID: 22973235 PMCID: PMC3433738 DOI: 10.3389/fphys.2012.00345] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 08/09/2012] [Indexed: 12/27/2022] Open
Abstract
Over the last decade, mouse models have become a popular instrument for studying cardiac arrhythmias. This review assesses in which respects a mouse heart is a miniature human heart, a suitable model for studying mechanisms of cardiac arrhythmias in humans and in which respects human and murine hearts differ. Section I considers the issue of scaling of mammalian cardiac (electro) physiology to body mass. Then, we summarize differences between mice and humans in cardiac activation (section II) and the currents underlying the action potential in the murine working myocardium (section III). Changes in cardiac electrophysiology in mouse models of heart disease are briefly outlined in section IV, while section V discusses technical considerations pertaining to recording cardiac electrical activity in mice. Finally, section VI offers general considerations on the influence of cardiac size on the mechanisms of tachy-arrhythmias.
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Affiliation(s)
- Sven Kaese
- Division of Experimental and Clinical Electrophysiology, Department of Cardiology and Angiology, University Hospital Münster Münster, Germany
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Suzuki T, Shioya T, Murayama T, Sugihara M, Odagiri F, Nakazato Y, Nishizawa H, Chugun A, Sakurai T, Daida H, Morimoto S, Kurebayashi N. Multistep ion channel remodeling and lethal arrhythmia precede heart failure in a mouse model of inherited dilated cardiomyopathy. PLoS One 2012; 7:e35353. [PMID: 22514734 PMCID: PMC3325934 DOI: 10.1371/journal.pone.0035353] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 03/14/2012] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND Patients with inherited dilated cardiomyopathy (DCM) frequently die with severe heart failure (HF) or die suddenly with arrhythmias, although these symptoms are not always observed at birth. It remains unclear how and when HF and arrhythmogenic changes develop in these DCM mutation carriers. In order to address this issue, properties of the myocardium and underlying gene expressions were studied using a knock-in mouse model of human inherited DCM caused by a deletion mutation ΔK210 in cardiac troponinT. METHODOLOGY/PRINCIPAL FINDINGS By 1 month, DCM mice had already enlarged hearts, but showed no symptoms of HF and a much lower mortality than at 2 months or later. At around 2 months, some would die suddenly with no clear symptoms of HF, whereas at 3 months, many of the survivors showed evident symptoms of HF. In isolated left ventricular myocardium (LV) from 2 month-mice, spontaneous activity frequently occurred and action potential duration (APD) was prolonged. Transient outward (I(to)) and ultrarapid delayed rectifier K(+) (I(Kur)) currents were significantly reduced in DCM myocytes. Correspondingly, down-regulation of Kv4.2, Kv1.5 and KChIP2 was evident in mRNA and protein levels. In LVs at 3-months, more frequent spontaneous activity, greater prolongation of APD and further down-regulation in above K(+) channels were observed. At 1 month, in contrast, infrequent spontaneous activity and down-regulation of Kv4.2, but not Kv1.5 or KChIP2, were observed. CONCLUSIONS/SIGNIFICANCE Our results suggest that at least three steps of electrical remodeling occur in the hearts of DCM model mice, and that the combined down-regulation of Kv4.2, Kv1.5 and KChIP2 prior to the onset of HF may play an important role in the premature sudden death in this DCM model. DCM mice at 1 month or before, on the contrary, are associated with low risk of death in spite of inborn disorder and enlarged heart.
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Affiliation(s)
- Takeshi Suzuki
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Takao Shioya
- Department of Physiology, Faculty of Medicine, Saga University, Saga, Japan
| | - Takashi Murayama
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Masami Sugihara
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Fuminori Odagiri
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Yuji Nakazato
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Hiroto Nishizawa
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Akihito Chugun
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Takashi Sakurai
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Hiroyuki Daida
- Department of Cardiovascular Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Sachio Morimoto
- Department of Clinical Pharmacology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Nagomi Kurebayashi
- Department of Cellular and Molecular Pharmacology, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
- * E-mail:
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Hoshino S, Omatsu-Kanbe M, Nakagawa M, Matsuura H. Postnatal developmental decline in IK1 in mouse ventricular myocytes isolated by the Langendorff perfusion method: comparison with the chunk method. Pflugers Arch 2012; 463:649-68. [PMID: 22415213 DOI: 10.1007/s00424-012-1084-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 01/18/2012] [Accepted: 02/08/2012] [Indexed: 12/01/2022]
Abstract
Expression and function of cardiac ion channels exhibit postnatal developmental changes, which, however, has not yet been proven in ventricular myocytes isolated using similar techniques. In this study, ventricular myocytes were enzymatically dissociated from mouse heart at different postnatal ages (including postnatal day 0) by similar techniques using Langendorff perfusion. Whole-cell patch-clamp experiments were performed to record action potentials, I (K1), I (Kr), I (Kur), I (ss), and I (Ca,L), in ventricular myocytes freshly isolated from postnatal days 0, 7, and 14 and adult mice. Viable ventricular myocytes of day-0 mouse heart exhibited spindle-shaped appearance having cell length of approximately 50 μm, which gradually developed to a rod-shaped one having clear cross striation with cell length of approximately 120 μm (adult). The action potential duration markedly shortened, while the resting membrane potential depolarized to a small but significant extent during postnatal development. I (K1) density was maximal in postnatal day-0 ventricular myocytes and gradually decreased during development, which was accompanied by postnatal depolarization of resting membrane potential. However, I (K1) density was markedly decreased by approximately 80% in postnatal day-0 ventricular myocytes, when isolated by the chunk method. Quantitative real-time polymerase chain reaction (PCR) and western blot analyses demonstrated higher Kir2.3 expression but lower expression levels of Kir2.1 and Kir2.2 in day-0 mouse ventricles, compared with those of day-14 and adult mouse ventricles. Whereas I (Kr) exhibited marked decrease during postnatal development, I (Kur), I (ss), and I (Ca,L) exhibited postnatal developmental increase. The present cell isolation method using the Langendorff perfusion thus found that, in mouse ventricles, I (K1) exhibited postnatal developmental decrease, associated with depolarization of resting potential.
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Affiliation(s)
- Shinsuke Hoshino
- Department of Pediatrics, Shiga University of Medical Science, Otsu, Shiga, 520-2192, Japan
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25
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Rivard K, Grandy SA, Douillette A, Paradis P, Nemer M, Allen BG, Fiset C. Overexpression of type 1 angiotensin II receptors impairs excitation-contraction coupling in the mouse heart. Am J Physiol Heart Circ Physiol 2011; 301:H2018-27. [DOI: 10.1152/ajpheart.01092.2010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Transgenic mice that overexpress human type 1 angiotensin II receptor (AT1R) in the heart develop cardiac hypertrophy. Previously, we have shown that in 6-mo AT1R mice, which exhibit significant cardiac remodeling, fractional shortening is decreased. However, it is not clear whether altered contractility is attributable to AT1R overexpression or is secondary to cardiac hypertrophy/remodeling. Thus the present study characterized the effects of AT1R overexpression on ventricular L-type Ca2+ currents ( ICaL), cell shortening, and Ca2+ handling in 50-day and 6-mo-old male AT1R mice. Echocardiography showed there was no evidence of cardiac hypertrophy in 50-day AT1R mice but that fractional shortening was decreased. Cellular experiments showed that cell shortening, ICaL, and Cav1.2 mRNA expression were significantly reduced in 50-day and 6-mo-old AT1R mice compared with controls. In addition, Ca2+ transients and caffeine-induced Ca2+ transients were reduced whereas the time to 90% Ca2+ transient decay was prolonged in both age groups of AT1R mice. Western blot analysis revealed that sarcoplasmic reticulum Ca2+-ATPase and Na+/Ca2+ exchanger protein expression was significantly decreased in 50-day and 6-mo AT1R mice. Overall, the data show that cardiac contractility and the mechanisms that underlie excitation-contraction coupling are altered in AT1R mice. Furthermore, since the alterations in contractility occur before the development of cardiac hypertrophy, it is likely that these changes are attributable to the increased activity of the renin-angiotensin system brought about by AT1R overexpression. Thus it is possible that AT1R blockade may help maintain cardiac contractility in individuals with heart disease.
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Affiliation(s)
- Katy Rivard
- Research Centre, Montreal Heart Institute, Montreal,
- Faculty of Pharmacy, Université de Montréal, Montreal,
| | - Scott A. Grandy
- Research Centre, Montreal Heart Institute, Montreal,
- Faculty of Pharmacy, Université de Montréal, Montreal,
| | - Annie Douillette
- Research Centre, Montreal Heart Institute, Montreal,
- Faculty of Pharmacy, Université de Montréal, Montreal,
| | | | | | | | - Céline Fiset
- Research Centre, Montreal Heart Institute, Montreal,
- Faculty of Pharmacy, Université de Montréal, Montreal,
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26
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de Boer TP, Houtman MJC, Compier M, van der Heyden MAG. The mammalian K(IR)2.x inward rectifier ion channel family: expression pattern and pathophysiology. Acta Physiol (Oxf) 2010; 199:243-56. [PMID: 20331539 DOI: 10.1111/j.1748-1716.2010.02108.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Inward rectifier currents based on K(IR)2.x subunits are regarded as essential components for establishing a stable and negative resting membrane potential in many excitable cell types. Pharmacological inhibition, null mutation in mice and dominant positive and negative mutations in patients reveal some of the important functions of these channels in their native tissues. Here we review the complex mammalian expression pattern of K(IR)2.x subunits and relate these to the outcomes of functional inhibition of the resultant channels. Correlations between expression and function in muscle and bone tissue are observed, while we recognize a discrepancy between neuronal expression and function.
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Affiliation(s)
- T P de Boer
- Department of Medical Physiology, UMCU, Utrecht, the Netherlands
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27
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28
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Regulated and aberrant glycosylation modulate cardiac electrical signaling. Proc Natl Acad Sci U S A 2009; 106:16517-22. [PMID: 19666501 DOI: 10.1073/pnas.0905414106] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Millions afflicted with Chagas disease and other disorders of aberrant glycosylation suffer symptoms consistent with altered electrical signaling such as arrhythmias, decreased neuronal conduction velocity, and hyporeflexia. Cardiac, neuronal, and muscle electrical signaling is controlled and modulated by changes in voltage-gated ion channel activity that occur through physiological and pathological processes such as development, epilepsy, and cardiomyopathy. Glycans attached to ion channels alter channel activity through isoform-specific mechanisms. Here we show that regulated and aberrant glycosylation modulate cardiac ion channel activity and electrical signaling through a cell-specific mechanism. Data show that nearly half of 239 glycosylation-associated genes (glycogenes) were significantly differentially expressed among neonatal and adult atrial and ventricular myocytes. The N-glycan structures produced among cardiomyocyte types were markedly variable. Thus, the cardiac glycome, defined as the complete set of glycan structures produced in the heart, is remodeled. One glycogene, ST8sia2, a polysialyltransferase, is expressed only in the neonatal atrium. Cardiomyocyte electrical signaling was compared in control and ST8sia2((-/-)) neonatal atrial and ventricular myocytes. Action potential waveforms and gating of less sialylated voltage-gated Na+ channels were altered consistently in ST8sia2((-/-)) atrial myocytes. ST8sia2 expression had no effect on ventricular myocyte excitability. Thus, the regulated (between atrium and ventricle) and aberrant (knockout in the neonatal atrium) expression of a single glycogene was sufficient to modulate cardiomyocyte excitability. A mechanism is described by which cardiac function is controlled and modulated through physiological and pathological processes that involve regulated and aberrant glycosylation.
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29
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Kaufmann SG, Westenbroek RE, Zechner C, Maass AH, Bischoff S, Muck J, Wischmeyer E, Scheuer T, Maier SKG. Functional protein expression of multiple sodium channel alpha- and beta-subunit isoforms in neonatal cardiomyocytes. J Mol Cell Cardiol 2009; 48:261-9. [PMID: 19426735 DOI: 10.1016/j.yjmcc.2009.04.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Revised: 04/14/2009] [Accepted: 04/29/2009] [Indexed: 11/29/2022]
Abstract
Voltage-gated sodium channels are composed of pore-forming alpha- and auxiliary beta-subunits and are responsible for the rapid depolarization of cardiac action potentials. Recent evidence indicates that neuronal tetrodotoxin (TTX) sensitive sodium channel alpha-subunits are expressed in the heart in addition to the predominant cardiac TTX-resistant Na(v)1.5 sodium channel alpha-subunit. These TTX-sensitive isoforms are preferentially localized in the transverse tubules of rodents. Since neonatal cardiomyocytes have yet to develop transverse tubules, we determined the complement of sodium channel subunits expressed in these cells. Neonatal rat ventricular cardiomyocytes were stained with antibodies specific for individual isoforms of sodium channel alpha- and beta-subunits. alpha-actinin, a component of the z-line, was used as an intracellular marker of sarcomere boundaries. TTX-sensitive sodium channel alpha-subunit isoforms Na(v)1.1, Na(v)1.2, Na(v)1.3, Na(v)1.4 and Na(v)1.6 were detected in neonatal rat heart but at levels reduced compared to the predominant cardiac alpha-subunit isoform, Na(v)1.5. Each of the beta-subunit isoforms (beta1-beta4) was also expressed in neonatal cardiac cells. In contrast to adult cardiomyocytes, the alpha-subunits are distributed in punctate clusters across the membrane surface of neonatal cardiomyocytes; no isoform-specific subcellular localization is observed. Voltage clamp recordings in the absence and presence of 20 nM TTX provided functional evidence for the presence of TTX-sensitive sodium current in neonatal ventricular myocardium which represents between 20 and 30% of the current, depending on membrane potential and experimental conditions. Thus, as in the adult heart, a range of sodium channel alpha-subunits are expressed in neonatal myocytes in addition to the predominant TTX-resistant Na(v)1.5 alpha-subunit and they contribute to the total sodium current.
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Affiliation(s)
- Susann G Kaufmann
- Medizinische Klinik und Poliklinik I, Universität Würzburg, Josef-Schneider-Strabetae 2, 97080 Würzburg, Germany
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30
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Rivard K, Trépanier-Boulay V, Rindt H, Fiset C. Electrical remodeling in a transgenic mouse model of alpha1B-adrenergic receptor overexpression. Am J Physiol Heart Circ Physiol 2008; 296:H704-18. [PMID: 19112097 DOI: 10.1152/ajpheart.00337.2008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiac-specific overexpression of wild-type alpha(1B)-adrenergic receptors (alpha(1B)-AR) in mice predisposes to dilated cardiomyopathy and sudden death. Although alpha-adrenergic stimulation is thought to contribute to induction of arrhythmias in heart failure, the electrophysiological consequences of chronic alpha(1)-adrenergic activation have not been clearly defined. Thus we characterized ventricular repolarization and monitored incidence of spontaneous arrhythmias in end-stage heart failure alpha(1B)-AR mice (9-12 mo) and younger alpha(1B)-AR mice (2-3 mo) that do not present signs of heart failure. Compared with aged-matched controls, the corrected QT interval was 34% longer in the 9- to 12-mo alpha(1B)-AR mice, and the action potential durations were also significantly prolonged in these mice. These changes were associated with a decrease in the density of the outward K(+) currents, Ca(2+)-independent transient, ultrarapid delayed rectifier, and steady state (at +30 mV, reduction of 68, 64, and 41%, respectively), and underlying K(+) channel expression. Electrocardiogram (ECG) recordings revealed that older alpha(1B)-AR mice exhibited spontaneous ventricular arrhythmias. The alterations in repolarization can contribute to these rhythm abnormalities and are likely caused by chronic alpha(1B)-AR activity. Additional data obtained in 2- to 3-mo alpha(1B)-AR mice clearly showed that electrical remodeling was already observed in younger transgenic animals. However, it appeared to be slightly less pronounced than in older mice. These results suggest that there are two waves of remodeling: one due to chronic alpha(1B)-AR activity, and a second due to heart failure. Taken together, these data provide strong evidence for a pathological role of chronic alpha(1B)-AR activity in the development of repolarization defects and ventricular arrhythmias.
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Affiliation(s)
- Katy Rivard
- Research Center, Montreal Heart Institute, 5000 Bélanger, Montréal, Québec, Canada H1T 1C8
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Wang LJ, Sobie EA. Mathematical model of the neonatal mouse ventricular action potential. Am J Physiol Heart Circ Physiol 2008; 294:H2565-75. [PMID: 18408122 DOI: 10.1152/ajpheart.01376.2007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Therapies for heart disease are based largely on our understanding of the adult myocardium. The dramatic differences in action potential (AP) shape between neonatal and adult cardiac myocytes, however, indicate that a different set of molecular interactions in neonatal myocytes necessitates different treatment for newborns. Computational modeling is useful for synthesizing data to determine how interactions between components lead to systems-level behavior, but this technique has not been used extensively to study neonatal heart cell function. We created a mathematical model of the neonatal (day 1) mouse myocyte by modifying, on the basis of experimental data, the densities and/or formulations of ion transport mechanisms in an adult cell model. The new model reproduces the characteristic AP shape of neonatal cells, with a brief plateau phase and longer duration than the adult (action potential duration at 80% repolarization = 60.1 vs. 12.6 ms). The simulation results are consistent with experimental data, including 1) decreased density and altered inactivation of transient outward K+ currents, 2) increased delayed rectifier K+ currents, 3) Ca2+ entry through T-type as well as L-type Ca2+ channels, 4) increased Ca2+ influx through Na+/Ca2+ exchange, and 5) Ca2+ transients resulting from transmembrane Ca2+ entry rather than release from the sarcoplasmic reticulum (SR). Simulations performed with the model generated novel predictions, including increased SR Ca2+ leak and elevated intracellular Na+ concentration in neonatal compared with adult myocytes. This new model can therefore be used for testing hypotheses and obtaining a better quantitative understanding of differences between neonatal and adult physiology.
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Affiliation(s)
- Linda J Wang
- Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, New York, New York, USA
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