201
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Lai YC, Li N, Lawrence W, Wang S, Levine A, Burchhardt DM, Pautler RG, Valderrábano M, Wehrens XH, Anderson AE. Myocardial remodeling and susceptibility to ventricular tachycardia in a model of chronic epilepsy. Epilepsia Open 2018; 3:213-223. [PMID: 29881800 PMCID: PMC5983128 DOI: 10.1002/epi4.12107] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/02/2018] [Indexed: 01/08/2023] Open
Abstract
Objective Sympathetic predominance and ventricular repolarization abnormalities represent epilepsy‐associated cardiac alterations and may underlie seizure‐induced ventricular arrhythmias. Myocardial ion channel and electrical remodeling have been described early in epilepsy development and may contribute to ventricular repolarization abnormalities and excitability. Using the pilocarpine‐induced acquired epilepsy model we sought to examine whether altered myocardial ion channel levels and electrophysiological changes also occur in animals with long‐standing epilepsy. Methods We examined myocardial adrenergic receptor and ion channel protein levels of epileptic and age‐matched sham rats (9–20 months old) using western blotting. Cardiac electrical properties were examined using optical mapping ex vivo and electrophysiology in vivo. We investigated the propensity for ventricular tachycardia (VT) and the effects of β‐adrenergic blockade on ventricular electrical properties and excitability in vivo. Results In animals with long‐standing epilepsy, we observed decreased myocardial voltage‐gated K+ channels Kv4.2 and Kv4.3, which are known to underlie early ventricular repolarization in rodents. Decreased β1 and increased α1A adrenergic receptor protein levels occurred in the myocardium of chronically epileptic animals consistent with elevated sympathetic tone. These animals exhibited many cardiac electrophysiological abnormalities, represented by longer QRS and corrected QT (QTc) intervals in vivo, slower conduction velocity ex vivo, and stimulation‐induced VT. Administration of a β‐adrenergic antagonist late in epilepsy was beneficial, as the therapy shortened the QTc interval and decreased stimulation‐induced VT. Significance Our findings demonstrate that myocardial ion channel remodeling and sympathetic predominance, risk factors for increased ventricular excitability and arrhythmias, persist in chronic epilepsy. The beneficial effects of β‐adrenergic antagonist treatment late in the course of epilepsy suggest that attenuating elevated sympathetic tone may represent a therapeutic target for ameliorating epilepsy‐associated cardiac morbidity.
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Affiliation(s)
- Yi-Chen Lai
- Department of Pediatrics Baylor College of Medicine Houston Texas U.S.A
| | - Na Li
- Department of Molecular Physiology and Biophysics Baylor College of Medicine Houston Texas U.S.A
| | - William Lawrence
- Department of Molecular Physiology and Biophysics Baylor College of Medicine Houston Texas U.S.A
| | - Sufen Wang
- DeBakey Heart and Vascular Center Methodist Hospital Research Institute Houston Texas U.S.A
| | - Amber Levine
- Department of Neuroscience Baylor College of Medicine Houston Texas U.S.A
| | | | - Robia G Pautler
- Department of Molecular Physiology and Biophysics Baylor College of Medicine Houston Texas U.S.A
| | - Miguel Valderrábano
- DeBakey Heart and Vascular Center Methodist Hospital Research Institute Houston Texas U.S.A
| | - Xander H Wehrens
- Department of Molecular Physiology and Biophysics Baylor College of Medicine Houston Texas U.S.A
| | - Anne E Anderson
- Department of Pediatrics Baylor College of Medicine Houston Texas U.S.A.,Department of Neuroscience Baylor College of Medicine Houston Texas U.S.A.,Department of Neurology Baylor College of Medicine Houston Texas U.S.A
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202
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Conant G, Lai BFL, Lu RXZ, Korolj A, Wang EY, Radisic M. High-Content Assessment of Cardiac Function Using Heart-on-a-Chip Devices as Drug Screening Model. Stem Cell Rev Rep 2018; 13:335-346. [PMID: 28429185 DOI: 10.1007/s12015-017-9736-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Drug discovery and development continues to be a challenge to the pharmaceutical industry despite great advances in cell and molecular biology that allow for the design of better targeted therapeutics. Many potential drug compounds fail during the clinical trial due to inefficacy and toxicity that were not predicted during preclinical stages. The fundamental problem lies with the use of traditional drug screening models that still largely rely on the use of cell lines or animal cell monolayers, which leads to lack of predictive power of human tissue and organ response to the drug candidates. More physiologically relevant systems are therefore critical in relieving the burden of high failure rates. Emerging knowledge and techniques in tissue engineering and microfabrication have enabled the development of micro-engineered systems - collectively known as organs-on-chips - that may lead to a paradigm shift in preclinical drug screening assays. In this review we explore the technological advances and challenges in the development of heart-on-a-chip models, by addressing current assessment methods for drug-induced cardiotoxicity and providing a perspective on the modifications that should be implemented to realize the full potential of this system.
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Affiliation(s)
- Genevieve Conant
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada
| | - Benjamin Fook Lun Lai
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Rick Xing Ze Lu
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Anastasia Korolj
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada
| | - Erika Yan Wang
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada
| | - Milica Radisic
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada.
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada.
- Toronto General Research Institute, Toronto, ON, Canada.
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203
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Yu Z, Chen Z, Wu Y, Chen R, Li M, Chen X, Qin S, Liang Y, Su Y, Ge J. Electrocardiographic parameters effectively predict ventricular tachycardia/fibrillation in acute phase and abnormal cardiac function in chronic phase of ST-segment elevation myocardial infarction. J Cardiovasc Electrophysiol 2018; 29:756-766. [PMID: 29399929 DOI: 10.1111/jce.13453] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 01/10/2018] [Accepted: 01/29/2018] [Indexed: 11/28/2022]
Affiliation(s)
- Ziqing Yu
- Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital; Fudan University; Shanghai PR China
- Shanghai Medical College; Fudan University; Shanghai PR China
| | - Zhangwei Chen
- Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital; Fudan University; Shanghai PR China
| | - Yuan Wu
- Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital; Fudan University; Shanghai PR China
| | - Ruizhen Chen
- Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital; Fudan University; Shanghai PR China
- Department of Cardiovascular Diseases, Key Laboratory of Viral Heart Diseases, Ministry of Public Health, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital; Fudan University; Shanghai PR China
| | - Minghui Li
- Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital; Fudan University; Shanghai PR China
- Department of Cardiovascular Diseases, Key Laboratory of Viral Heart Diseases, Ministry of Public Health, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital; Fudan University; Shanghai PR China
| | - Xueying Chen
- Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital; Fudan University; Shanghai PR China
| | - Shengmei Qin
- Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital; Fudan University; Shanghai PR China
| | - Yixiu Liang
- Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital; Fudan University; Shanghai PR China
| | - Yangang Su
- Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital; Fudan University; Shanghai PR China
| | - Junbo Ge
- Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital; Fudan University; Shanghai PR China
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204
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Liu M, Shi G, Zhou A, Rupert CE, Coulombe KLK, Dudley SC. Activation of the unfolded protein response downregulates cardiac ion channels in human induced pluripotent stem cell-derived cardiomyocytes. J Mol Cell Cardiol 2018; 117:62-71. [PMID: 29474817 DOI: 10.1016/j.yjmcc.2018.02.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 02/03/2018] [Accepted: 02/14/2018] [Indexed: 10/18/2022]
Abstract
RATIONALE Heart failure is characterized by electrical remodeling that contributes to arrhythmic risk. The unfolded protein response (UPR) is active in heart failure and can decrease protein levels by increasing mRNA decay, accelerating protein degradation, and inhibiting protein translation. OBJECTIVE Therefore, we investigated whether the UPR downregulated cardiac ion channels that may contribute to arrhythmogenic electrical remodeling. METHODS Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were used to study cardiac ion channels. Action potentials (APs) and ion channel currents were measured by patch clamp recording. The mRNA and protein levels of channels and the UPR effectors were determined by quantitative RT-PCR and Western blotting. Tunicamycin (TM, 50 ng/mL and 5 μg/mL), GSK2606414 (GSK, 300 nmol/L), and 4μ8C (5 μmol/L) were utilized to activate the UPR, inhibit protein kinase-like ER kinase (PERK) and inositol-requiring protein-1 (IRE1), respectively. RESULTS TM-induced activation of the UPR caused significant prolongation of the AP duration (APD) and a reduction of the maximum upstroke velocity (dV/dtmax) of the AP phase 0 in both acute (20-24 h) and chronic treatment (6 days). These changes were explained by reductions in the sodium, L-type calcium, the transient outward and rapidly/slowly activating delayed rectifier potassium currents. Nav1.5, Cav1.2, Kv4.3, and KvLQT1 channels showed concomitant reductions in mRNA and protein levels under activated UPR. Inhibition of PERK or IRE1 shortened the APD and reinstated dV/dtmax. The PERK branch regulated Nav1.5, Kv4.3, hERG, and KvLQT1. The IRE1 branch regulated Nav1.5, hERG, KvLQT1, and Cav1.2. CONCLUSIONS Activated UPR downregulates all major cardiac ion currents and results in electrical remodeling in hiPSC-CMs. Both PERK and IRE1 branches downregulate Nav1.5, hERG, and KvLQT1. The PERK branch specifically downregulates Kv4.3, while the IRE1 branch downregulates Cav1.2. Therefore, the UPR contributed to electrical remodeling, and targeting the UPR might be anti-arrhythmic.
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Affiliation(s)
- Man Liu
- Division of Cardiology, Dept. of Medicine, the Lillehei Heart Institute, University of Minnesota, Minneapolis, MN, United States
| | - Guangbin Shi
- Division of Cardiology, Dept. of Medicine, The Warren Alpert School of Medicine, Brown University; Lifespan Cardiovascular Research Center, Providence, RI, United States
| | - Anyu Zhou
- Division of Cardiology, Dept. of Medicine, The Warren Alpert School of Medicine, Brown University; Lifespan Cardiovascular Research Center, Providence, RI, United States
| | - Cassady E Rupert
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, United States
| | - Kareen L K Coulombe
- Center for Biomedical Engineering, School of Engineering, Brown University, Providence, RI, United States
| | - Samuel C Dudley
- Division of Cardiology, Dept. of Medicine, the Lillehei Heart Institute, University of Minnesota, Minneapolis, MN, United States.
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205
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Lazzerini PE, Capecchi PL, Galeazzi M, Laghi-Pasini F. Biologic drugs and arrhythmic risk in chronic inflammatory arthritis: the good and the bad. Immunol Res 2018; 65:262-275. [PMID: 27423435 DOI: 10.1007/s12026-016-8833-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Increasing evidence indicates that patients with chronic inflammatory arthritis (CIA), including rheumatoid arthritis and spondyloarthropathies, have an increased risk of arrhythmic events, significantly contributing to the higher cardiovascular disease (CVD) morbidity and mortality observed in these subjects compared to the general population. Although the mechanisms accounting for such an arrhythmogenic substrate are not fully understood, the main role is probably played by chronic systemic inflammation, able to accelerate the development of structural CVD, as well as to directly affect cardiac electrophysiology. In the past decade, biologic therapies have revolutionized the treatment of CIA by highly enhancing the probability to effectively control disease activity and its systemic consequences, including cardiovascular involvement. Accordingly, accumulating data demonstrated that by potently inhibiting systemic inflammation, biologic drugs can reduce CVD progression and ameliorate arrhythmic risk parameters, with a putative beneficial impact on arrhythmia incidence. Nevertheless, a significant number of reports from clinical trials and postmarketing experience suggest that some of these medications, particularly TNF inhibitor monoclonal antibodies and rituximab, may in some circumstances precipitate arrhythmia occurrence, probably by acutely amplifying myocardial electric instability intrinsically associated with these diseases. In this review, we analyze the intricate link between biologic drugs and arrhythmias in CIA in the effort to identify which factors are involved in the fine-tuning of antiarrhythmic/pro-arrhythmic balance, and understand how this knowledge should be translated in the clinical practice to obtain the most favorable benefit-to-risk profile when biologic drugs are used in these patients.
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Affiliation(s)
- Pietro Enea Lazzerini
- Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Policlinico "Le Scotte", Viale Bracci, Siena, Italy.
| | - Pier Leopoldo Capecchi
- Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Policlinico "Le Scotte", Viale Bracci, Siena, Italy
| | - Mauro Galeazzi
- Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Policlinico "Le Scotte", Viale Bracci, Siena, Italy
| | - Franco Laghi-Pasini
- Department of Medical Sciences, Surgery and Neurosciences, University of Siena, Policlinico "Le Scotte", Viale Bracci, Siena, Italy
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206
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Zhang X, Yoon JY, Morley M, McLendon JM, Mapuskar KA, Gutmann R, Mehdi H, Bloom HL, Dudley SC, Ellinor PT, Shalaby AA, Weiss R, Tang WHW, Moravec CS, Singh M, Taylor AL, Yancy CW, Feldman AM, McNamara DM, Irani K, Spitz DR, Breheny P, Margulies KB, London B, Boudreau RL. A common variant alters SCN5A-miR-24 interaction and associates with heart failure mortality. J Clin Invest 2018; 128:1154-1163. [PMID: 29457789 DOI: 10.1172/jci95710] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 12/12/2017] [Indexed: 12/19/2022] Open
Abstract
SCN5A encodes the voltage-gated Na+ channel NaV1.5 that is responsible for depolarization of the cardiac action potential and rapid intercellular conduction. Mutations disrupting the SCN5A coding sequence cause inherited arrhythmias and cardiomyopathy, and single-nucleotide polymorphisms (SNPs) linked to SCN5A splicing, localization, and function associate with heart failure-related sudden cardiac death. However, the clinical relevance of SNPs that modulate SCN5A expression levels remains understudied. We recently generated a transcriptome-wide map of microRNA (miR) binding sites in human heart, evaluated their overlap with common SNPs, and identified a synonymous SNP (rs1805126) adjacent to a miR-24 site within the SCN5A coding sequence. This SNP was previously shown to reproducibly associate with cardiac electrophysiological parameters, but was not considered to be causal. Here, we show that miR-24 potently suppresses SCN5A expression and that rs1805126 modulates this regulation. We found that the rs1805126 minor allele associates with decreased cardiac SCN5A expression and that heart failure subjects homozygous for the minor allele have decreased ejection fraction and increased mortality, but not increased ventricular tachyarrhythmias. In mice, we identified a potential basis for this in discovering that decreased Scn5a expression leads to accumulation of myocardial reactive oxygen species. Together, these data reiterate the importance of considering the mechanistic significance of synonymous SNPs as they relate to miRs and disease, and highlight a surprising link between SCN5A expression and nonarrhythmic death in heart failure.
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Affiliation(s)
- Xiaoming Zhang
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Jin-Young Yoon
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Michael Morley
- Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jared M McLendon
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Kranti A Mapuskar
- Department of Radiation Oncology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Rebecca Gutmann
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Haider Mehdi
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Heather L Bloom
- Department of Medicine, Emory University Medical Center, Atlanta, Georgia, USA
| | - Samuel C Dudley
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Patrick T Ellinor
- Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Alaa A Shalaby
- Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - Raul Weiss
- Department of Internal Medicine, The Ohio State University Medical Center, Columbus, Ohio, USA
| | - W H Wilson Tang
- Department of Cardiovascular Medicine, Cleveland Clinic Lerner College of Medicine, Cleveland, Ohio, USA
| | - Christine S Moravec
- Department of Molecular Cardiology, Cleveland Clinic Lerner College of Medicine, Cleveland, Ohio, USA
| | - Madhurmeet Singh
- Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - Anne L Taylor
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York, USA
| | - Clyde W Yancy
- Division of Cardiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Arthur M Feldman
- Department of Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania, USA
| | - Dennis M McNamara
- Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - Kaikobad Irani
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Douglas R Spitz
- Department of Radiation Oncology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Patrick Breheny
- Department of Biostatistics, University of Iowa College of Public Heath, Iowa City, Iowa, USA
| | - Kenneth B Margulies
- Department of Internal Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Barry London
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Ryan L Boudreau
- Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
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Abstract
Heart failure (HF) has been referred to as the cardiovascular epidemic of our time. Understanding the molecular determinants of HF disease progression and mortality risk is of utmost importance. In this issue of the JCI, Zhang et al. uncover an important link between clinical HF mortality risk and a common variant that regulates SCN5A expression through microRNA-dependent (miR-dependent)mechanisms. They also demonstrate that haploinsufficiency of SCN5A is associated with increased accumulation of reactive oxygen species (ROS) in a genetically engineered murine model. Their data suggest that even modest depression of SCN5A expression may promote pathologic cardiac remodeling and progression of HF.
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208
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Holland NA, Francisco JT, Johnson SC, Morgan JS, Dennis TJ, Gadireddy NR, Tulis DA. Cyclic Nucleotide-Directed Protein Kinases in Cardiovascular Inflammation and Growth. J Cardiovasc Dev Dis 2018; 5:E6. [PMID: 29367584 PMCID: PMC5872354 DOI: 10.3390/jcdd5010006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 01/17/2018] [Accepted: 01/19/2018] [Indexed: 02/08/2023] Open
Abstract
Cardiovascular disease (CVD), including myocardial infarction (MI) and peripheral or coronary artery disease (PAD, CAD), remains the number one killer of individuals in the United States and worldwide, accounting for nearly 18 million (>30%) global deaths annually. Despite considerable basic science and clinical investigation aimed at identifying key etiologic components of and potential therapeutic targets for CVD, the number of individuals afflicted with these dreaded diseases continues to rise. Of the many biochemical, molecular, and cellular elements and processes characterized to date that have potential to control foundational facets of CVD, the multifaceted cyclic nucleotide pathways continue to be of primary basic science and clinical interest. Cyclic adenosine monophosphate (cyclic AMP) and cyclic guanosine monophosphate (cyclic GMP) and their plethora of downstream protein kinase effectors serve ubiquitous roles not only in cardiovascular homeostasis but also in the pathogenesis of CVD. Already a major target for clinical pharmacotherapy for CVD as well as other pathologies, novel and potentially clinically appealing actions of cyclic nucleotides and their downstream targets are still being discovered. With this in mind, this review article focuses on our current state of knowledge of the cyclic nucleotide-driven serine (Ser)/threonine (Thr) protein kinases in CVD with particular emphasis on cyclic AMP-dependent protein kinase (PKA) and cyclic GMP-dependent protein kinase (PKG). Attention is given to the regulatory interactions of these kinases with inflammatory components including interleukin 6 signals, with G protein-coupled receptor and growth factor signals, and with growth and synthetic transcriptional platforms underlying CVD pathogenesis. This article concludes with a brief discussion of potential future directions and highlights the importance for continued basic science and clinical study of cyclic nucleotide-directed protein kinases as emerging and crucial controllers of cardiac and vascular disease pathologies.
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Affiliation(s)
- Nathan A Holland
- Department of Physiology, Brody School of Medicine, East Carolina University, 600 Moye Boulevard, Greenville, NC 27834, USA.
| | - Jake T Francisco
- Department of Physiology, Brody School of Medicine, East Carolina University, 600 Moye Boulevard, Greenville, NC 27834, USA.
| | - Sean C Johnson
- Department of Physiology, Brody School of Medicine, East Carolina University, 600 Moye Boulevard, Greenville, NC 27834, USA.
| | - Joshua S Morgan
- Department of Physiology, Brody School of Medicine, East Carolina University, 600 Moye Boulevard, Greenville, NC 27834, USA.
| | - Troy J Dennis
- Department of Physiology, Brody School of Medicine, East Carolina University, 600 Moye Boulevard, Greenville, NC 27834, USA.
| | - Nishitha R Gadireddy
- Department of Physiology, Brody School of Medicine, East Carolina University, 600 Moye Boulevard, Greenville, NC 27834, USA.
| | - David A Tulis
- Department of Physiology, Brody School of Medicine, East Carolina University, 600 Moye Boulevard, Greenville, NC 27834, USA.
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209
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Yamada S, Fong MC, Hsiao YW, Chang SL, Tsai YN, Lo LW, Chao TF, Lin YJ, Hu YF, Chung FP, Liao JN, Chang YT, Li HY, Higa S, Chen SA. Impact of Renal Denervation on Atrial Arrhythmogenic Substrate in Ischemic Model of Heart Failure. J Am Heart Assoc 2018; 7:JAHA.117.007312. [PMID: 29358197 PMCID: PMC5850156 DOI: 10.1161/jaha.117.007312] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Myocardial infarction increases the risk of heart failure (HF) and atrial fibrillation. Renal denervation (RDN) might suppress the development of atrial remodeling. This study aimed to elucidate the molecular mechanism of RDN in the suppression of atrial fibrillation in a HF model after myocardial infarction. METHODS AND RESULTS HF rabbits were created 4 weeks after coronary ligation. Rabbits were classified into 3 groups: normal control (n=10), HF (n=10), and HF-RDN (n=6). Surgical and chemical RDN were approached through midabdominal incisions in HF-RDN. Left anterior descending coronary artery in HF and HF-RDN was ligated to create myocardial infarction. After electrophysiological study, the rabbits were euthanized and the left atrial appendage was harvested for real-time polymerase chain reaction analysis and Trichrome stain. Left atrial dimension and left ventricular mass were smaller in HF-RDN by echocardiography compared with HF. Attenuated atrial fibrosis and tyrosine hydroxylase levels were observed in HF-RDN compared with HF. The mRNA expressions of Cav1.2, Nav1.5, Kir2.1, KvLQT1, phosphoinositide 3-kinase, AKT, and endothelial nitric oxide synthase in HF-RDN were significantly higher compared with HF. The effective refractory period and action potential duration of HF-RDN were significantly shorter compared with HF. Decreased atrial fibrillation inducibility was noted in HF-RDN compared with HF (50% versus 100%, P<0.05). CONCLUSIONS RDN reversed atrial electrical and structural remodeling, and suppressed the atrial fibrillation inducibility in an ischemic HF model. The beneficial effect of RDN may be related to prevention of the downregulation of the phosphoinositide 3-kinase/AKT/endothelial nitric oxide synthase signaling pathway.
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Affiliation(s)
- Shinya Yamada
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Department of Cardiovascular Medicine, Fukushima Medical University, Fukushima, Japan
| | - Man-Cai Fong
- Heart Center, Cheng Hsin General Hospital, Taipei, Taiwan.,Division of Cardiology, Department of Medicine, National Defense Medical Center, Taipei, Taiwan
| | - Ya-Wen Hsiao
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Shih-Lin Chang
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan .,Institute of Clinical Medicine, and Cardiovascular Research Institute, National Yang-Ming University, Taipei, Taiwan
| | - Yung-Nan Tsai
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, and Cardiovascular Research Institute, National Yang-Ming University, Taipei, Taiwan
| | - Li-Wei Lo
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, and Cardiovascular Research Institute, National Yang-Ming University, Taipei, Taiwan
| | - Tze-Fan Chao
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, and Cardiovascular Research Institute, National Yang-Ming University, Taipei, Taiwan
| | - Yenn-Jiang Lin
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, and Cardiovascular Research Institute, National Yang-Ming University, Taipei, Taiwan
| | - Yu-Feng Hu
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, and Cardiovascular Research Institute, National Yang-Ming University, Taipei, Taiwan
| | - Fa-Po Chung
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, and Cardiovascular Research Institute, National Yang-Ming University, Taipei, Taiwan
| | - Jo-Nan Liao
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, and Cardiovascular Research Institute, National Yang-Ming University, Taipei, Taiwan
| | - Yao-Ting Chang
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, and Cardiovascular Research Institute, National Yang-Ming University, Taipei, Taiwan
| | - Hsing-Yuan Li
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Department of Pediatrics, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Satoshi Higa
- Division of Cardiovascular Medicine, Cardiac Electrophysiology and Pacing Laboratory, Makiminato Central Hospital, Okinawa, Japan
| | - Shih-Ann Chen
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Institute of Clinical Medicine, and Cardiovascular Research Institute, National Yang-Ming University, Taipei, Taiwan
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210
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Electrical and histological remodeling of the pulmonary vein in 2K1C hypertensive rats: Indication of initiation and maintenance of atrial fibrillation. Anatol J Cardiol 2018; 19:169-175. [PMID: 29339676 PMCID: PMC5864765 DOI: 10.14744/anatoljcardiol.2017.7844] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Objective Hypertension is a significant risk factor for atrial fibrillation (AF). The role of pulmonary vein (PV) remodeling in the mechanistic association between hypertension and AF is not definitive. In this study, we aimed to identify changes in the electrophysiology and histology in PVs in two-kidney, one-clip (2K1C) hypertensive rats. Methods Fifty male Sprague-Dawley rats were classified into the 2K1C and sham-operated groups. The systolic blood pressure was measured every 2 weeks. The left atrial diameter was measured by transthoracic echocardiography. Left superior PV (LSPV) and left atrial (LA) fibrosis was evaluated by Masson’s trichrome staining. The expression of fibrosis markers [angiotensin II (Ang II), transforming growth factor-β1 (TGF-β1), matrix metalloproteinase-2 (MMP-2), and collagen I (Col I)] and ion channels [Kir2.1, Kir2.3, Cav1.2, and Nav1.5] in LSVP was quantified by western blot. Conventional microelectrodes were used to record the action potential duration at 90% repolarization (APD90) and effective refractory period (ERP) in isolated LA. Results At 4 months, the 2K1C hypertensive rats developed LA dilation. Col deposition in LSPV and left atrium and expression of TGF-β1, MMP-2, and Col I in LSPV were significantly increased in 2K1C hypertensive rats. In addition, hypertension reduced the expression of Nav1.5 and Kir2.1, although there were no significant differences in APD90; ERP; and expression of Ang II, Kir2.3, and Cav1.2 between the two groups. Conclusion Hypertension may lead to changes in the electrophysiology and histology of rats PVs, which is characterized by significant reduction in the expression of Nav1.5 and Kir2.1 and increase in interstitial fibrosis. These observations may clarify the role of PVs in the mechanistic association between hypertension and AF.
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Deyawe A, Kasimova MA, Delemotte L, Loussouarn G, Tarek M. Studying Kv Channels Function using Computational Methods. Methods Mol Biol 2018; 1684:321-341. [PMID: 29058202 DOI: 10.1007/978-1-4939-7362-0_24] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In recent years, molecular modeling techniques, combined with MD simulations, provided significant insights on voltage-gated (Kv) potassium channels intrinsic properties. Among the success stories are the highlight of molecular level details of the effects of mutations, the unraveling of several metastable intermediate states, and the influence of a particular lipid, PIP2, in the stability and the modulation of Kv channel function. These computational studies offered a detailed view that could not have been reached through experimental studies alone. With the increase of cross disciplinary studies, numerous experiments provided validation of these computational results, which endows an increase in the reliability of molecular modeling for the study of Kv channels. This chapter offers a description of the main techniques used to model Kv channels at the atomistic level.
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Affiliation(s)
- Audrey Deyawe
- Structure et Réactivité des Systèmes Moléculaires Complexes, CNRS, Université de Lorraine, Nancy, France
| | - Marina A Kasimova
- Structure et Réactivité des Systèmes Moléculaires Complexes, CNRS, Université de Lorraine, Nancy, France
| | - Lucie Delemotte
- Structure et Réactivité des Systèmes Moléculaires Complexes, CNRS, Université de Lorraine, Nancy, France
| | - Gildas Loussouarn
- L'institut du thorax, Inserm, CNRS, Université de Nantes, Nantes, France
| | - Mounir Tarek
- Structure et Réactivité des Systèmes Moléculaires Complexes, CNRS, Université de Lorraine, Nancy, France.
- CNRS, Unité Mixte de Recherches 7565, Université de Lorraine, Boulevard des Aiguillettes, BP 70239, 54506, Vandoeuvre-lès-Nancy, France.
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Zhao X, Gu T. Dysfunctional Hyperpolarization-Activated Cyclic Nucleotide-gated Ion Channels in Cardiac Diseases. Braz J Cardiovasc Surg 2017; 31:203-6. [PMID: 27556324 PMCID: PMC5062718 DOI: 10.5935/1678-9741.20160030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are reverse
voltage-dependent, and their activation depends on the hyperpolarization of the
membrane and may be directly or indirectly regulated by the cyclic adenosine
monophosphate (cAMP) or other signal-transduction cascades. The distribution,
quantity and activation states of HCN channels differ in tissues throughout the
body. Evidence exhibits that HCN channels play critical roles in the generation
and conduction of the electrical impulse and the physiopathological process of
some cardiac diseases. They may constitute promising drug targets in the
treatment of these cardiac diseases. Pharmacological treatment targeting HCN
channels is of benefit to these cardiac conditions.
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Affiliation(s)
- Xiaoqi Zhao
- Department of Cardiac Surgery ICU, First Affiliated Hospital, China Medical University, Shenyang, China
| | - Tianxiang Gu
- Department of Cardiac Surgery ICU, First Affiliated Hospital, China Medical University, Shenyang, China
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213
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Reentry via high-frequency pacing in a mathematical model for human-ventricular cardiac tissue with a localized fibrotic region. Sci Rep 2017; 7:15350. [PMID: 29127361 PMCID: PMC5681702 DOI: 10.1038/s41598-017-15735-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 10/02/2017] [Indexed: 11/08/2022] Open
Abstract
Localized heterogeneities, caused by the regional proliferation of fibroblasts, occur in mammalian hearts because of diseases like myocardial infarction. Such fibroblast clumps can become sources of pathological reentrant activities, e.g., spiral or scroll waves of electrical activation in cardiac tissue. The occurrence of reentry in cardiac tissue with heterogeneities, such as fibroblast clumps, can depend on the frequency at which the medium is paced. Therefore, it is important to study the reentry-initiating potential of such fibroblast clumps at different frequencies of pacing. We investigate the arrhythmogenic effects of fibroblast clumps at high- and low-frequency pacing. We find that reentrant waves are induced in the medium more prominently at high-frequency pacing than with low-frequency pacing. We also study the other factors that affect the potential of fibroblast clumps to induce reentry in cardiac tissue. In particular, we show that the ability of a fibroblast clump to induce reentry depends on the size of the clump, the distribution and percentage of fibroblasts in the clump, and the excitability of the medium. We study the process of reentry in two-dimensional and a three-dimensional mathematical models for cardiac tissue.
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214
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Lane JD, Tinker A. Have the Findings from Clinical Risk Prediction and Trials Any Key Messages for Safety Pharmacology? Front Physiol 2017; 8:890. [PMID: 29163223 PMCID: PMC5681497 DOI: 10.3389/fphys.2017.00890] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 10/20/2017] [Indexed: 01/28/2023] Open
Abstract
Anti-arrhythmic drugs are a mainstay in the management of symptoms related to arrhythmias, and are adjuncts in prevention and treatment of life-threatening ventricular arrhythmias. However, they also have the potential for pro-arrhythmia and thus the prediction of arrhythmia predisposition and drug response are critical issues. Clinical trials are the latter stages in the safety testing and efficacy process prior to market release, and as such serve as a critical safeguard. In this review, we look at some of the lessons to be learned from approaches to arrhythmia prediction in patients, clinical trials of drugs used in the treatment of arrhythmias, and the implications for the design of pre-clinical safety pharmacology testing.
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Affiliation(s)
- Jem D. Lane
- William Harvey Heart Centre, Barts and The London School of Medicine and Dentistry, London, United Kingdom
- Department of Cardiac Electrophysiology, Barts Heart Centre, St Bartholomew's Hospital, London, United Kingdom
| | - Andrew Tinker
- William Harvey Heart Centre, Barts and The London School of Medicine and Dentistry, London, United Kingdom
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215
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Ionic mechanisms of the action of anaesthetics on sinoatrial node automaticity. Eur J Pharmacol 2017; 814:63-72. [DOI: 10.1016/j.ejphar.2017.08.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Revised: 07/06/2017] [Accepted: 08/07/2017] [Indexed: 12/11/2022]
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216
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QRS duration reflects underlying changes in conduction velocity during increased intraventricular pressure and heart failure. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 130:394-403. [DOI: 10.1016/j.pbiomolbio.2017.08.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 08/04/2017] [Accepted: 08/07/2017] [Indexed: 11/19/2022]
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217
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Hung CL, Lai YJ, Chi PC, Chen LC, Tseng YM, Kuo JY, Lin CI, Chen YC, Lin SJ, Yeh HI. Dose-related ethanol intake, Cx43 and Nav1.5 remodeling: Exploring insights of altered ventricular conduction and QRS fragmentation in excessive alcohol users. J Mol Cell Cardiol 2017; 114:150-160. [PMID: 29097069 DOI: 10.1016/j.yjmcc.2017.10.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 10/05/2017] [Accepted: 10/27/2017] [Indexed: 02/05/2023]
Abstract
BACKGROUND Chronic, excessive ethanol intake has been linked with various electrical instabilities, conduction disturbances, and even sudden cardiac death, but the underlying cause for the latter is insufficiently delineated. METHODS We studied surface electrocardiography (ECG) in a community-dwelling cohort with moderate-to-heavy daily alcohol intake (grouped as >90g/day, ≤90g/day, and nonintake). RESULTS Compared with nonintake, heavier alcohol users showed markedly widened QRS duration and higher prevalence of QRS fragmentation (64.3%, 50.9%, and 33.7%, respectively, χ2 12.0, both p<0.05) on surface ECG across the 3 groups. These findings were successfully recapitulated in 14-week-old C57BL/6 mice that were chronically given a 4% or 6% alcohol diet and showed dose-related slower action potential upstroke, reduced resting membrane potential, and disorganized or decreased intraventricular conduction (all p<0.05). Immunodetection further revealed increased ventricular collagen I depots with Cx43 downregulation and remodeling, together with clustered and diminished membrane Nav1.5 distribution. Administration of Cx43 blocker (heptanol) and Nav1.5 inhibitor (tetrodotoxin) in the mice each attenuated the suppression ventricular conduction compared with nonintake mice (p<0.05). CONCLUSIONS Chronic excessive alcohol ingestion is associated with dose-related phenotypic intraventricular conduction disturbances and QRS fragmentation that can be recapitulated in mice. The mechanisms may involve suppressed gap junction and sodium channel functions, together with enhanced cardiac fibrosis that may contribute to arrhythmogenesis.
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Affiliation(s)
- Chung-Lieh Hung
- Department of Medicine, MacKay Medical College, New Taipei City, Taiwan; Division of Cardiology, Department of Internal Medicine, National Yang-Ming University, Taipei, Taiwan; Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan; Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan
| | - Yu-Jun Lai
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Po-Ching Chi
- Department of Medicine, MacKay Medical College, New Taipei City, Taiwan; Division of Cardiology, Department of Internal Medicine, National Yang-Ming University, Taipei, Taiwan; Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Liang-Chia Chen
- Department of Mechanical Engineering, National Taiwan University, Taipei, Taiwan
| | - Ya-Ming Tseng
- Division of Cardiology, Department of Internal Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Jen-Yuan Kuo
- Department of Medicine, MacKay Medical College, New Taipei City, Taiwan; Division of Cardiology, Department of Internal Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Cheng-I Lin
- Institute of Physiology, National Defense Medical Center, Taipei, Taiwan; Department of Biophysics, National Defense Medical Center, Taipei, Taiwan
| | - Yao-Chang Chen
- Biomedical Engineering, National Defense Medical Center, Taipei, Taiwan
| | - Shing-Jong Lin
- Institute of Clinical Medicine, and, Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan
| | - Hung-I Yeh
- Department of Medicine, MacKay Medical College, New Taipei City, Taiwan; Division of Cardiology, Department of Internal Medicine, National Yang-Ming University, Taipei, Taiwan.
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218
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Cho JH, Zhang R, Kilfoil PJ, Gallet R, de Couto G, Bresee C, Goldhaber JI, Marbán E, Cingolani E. Delayed Repolarization Underlies Ventricular Arrhythmias in Rats With Heart Failure and Preserved Ejection Fraction. Circulation 2017; 136:2037-2050. [PMID: 28974519 DOI: 10.1161/circulationaha.117.028202] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 09/07/2017] [Indexed: 12/20/2022]
Abstract
BACKGROUND Heart failure with preserved ejection fraction (HFpEF) represents approximately half of heart failure, and its incidence continues to increase. The leading cause of mortality in HFpEF is sudden death, but little is known about the underlying mechanisms. METHODS Dahl salt-sensitive rats were fed a high-salt diet (8% NaCl) from 7 weeks of age to induce HFpEF (n=38). Rats fed a normal-salt diet (0.3% NaCl) served as controls (n=13). Echocardiograms were performed to assess systolic and diastolic function from 14 weeks of age. HFpEF-verified and control rats underwent programmed electrical stimulation. Corrected QT interval was measured by surface ECG. The mechanisms of ventricular arrhythmias (VA) were probed by optical mapping, whole-cell patch clamp to measure action potential duration and ionic currents, and quantitative polymerase chain reaction and Western blotting to investigate changes in ion channel expression. RESULTS After 7 weeks of a high-salt diet, 31 of 38 rats showed diastolic dysfunction and preserved ejection fraction along with signs of heart failure and hence were diagnosed with HFpEF. Programmed electric stimulation demonstrated increased susceptibility to VA in HFpEF rats (P<0.001 versus controls). The arrhythmogenicity index was increased (P<0.001) and the corrected QT interval on ECG was prolonged (P<0.001) in HFpEF rats. Optical mapping of HFpEF hearts demonstrated prolonged action potentials (P<0.05) and multiple reentry circuits during induced VA. Single-cell recordings of cardiomyocytes isolated from HFpEF rats confirmed a delay of repolarization (P=0.001) and revealed downregulation of transient outward potassium current (Ito; P<0.05). The rapid components of the delayed rectifier potassium current (IKr) and the inward rectifier potassium current (IK1) were also downregulated (P<0.05), but the current densities were much lower than for Ito. In accordance with the reduction of Ito, both Kcnd3 transcript and Kv4.3 protein levels were decreased in HFpEF rat hearts. CONCLUSIONS Susceptibility to VA was markedly increased in rats with HFpEF. Underlying abnormalities include QT prolongation, delayed repolarization from downregulation of potassium currents, and multiple reentry circuits during VA. Our findings are consistent with the hypothesis that potassium current downregulation leads to abnormal repolarization in HFpEF, which in turn predisposes to VA and sudden cardiac death.
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Affiliation(s)
- Jae Hyung Cho
- Cedars-Sinai Heart Institute, Los Angeles, CA (J.H.C., R.Z., P.J.K., G.d.C., J.I.G., E.M., E.C.)
| | - Rui Zhang
- Cedars-Sinai Heart Institute, Los Angeles, CA (J.H.C., R.Z., P.J.K., G.d.C., J.I.G., E.M., E.C.)
| | - Peter J Kilfoil
- Cedars-Sinai Heart Institute, Los Angeles, CA (J.H.C., R.Z., P.J.K., G.d.C., J.I.G., E.M., E.C.)
| | - Romain Gallet
- Henri Mondor University Hospital, Créteil, France (R.G.)
| | - Geoffrey de Couto
- Cedars-Sinai Heart Institute, Los Angeles, CA (J.H.C., R.Z., P.J.K., G.d.C., J.I.G., E.M., E.C.)
| | - Catherine Bresee
- Biostatistics and Bioinformatics Research Center, Cedars-Sinai Medical Center, Los Angeles, CA (C.B.)
| | - Joshua I Goldhaber
- Cedars-Sinai Heart Institute, Los Angeles, CA (J.H.C., R.Z., P.J.K., G.d.C., J.I.G., E.M., E.C.)
| | - Eduardo Marbán
- Cedars-Sinai Heart Institute, Los Angeles, CA (J.H.C., R.Z., P.J.K., G.d.C., J.I.G., E.M., E.C.)
| | - Eugenio Cingolani
- Cedars-Sinai Heart Institute, Los Angeles, CA (J.H.C., R.Z., P.J.K., G.d.C., J.I.G., E.M., E.C.)
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219
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Lin YK, Chen YA, Lee TI, Chen YC, Chen SA, Chen YJ. Aging Modulates the Substrate and Triggers Remodeling in Atrial Fibrillation. Circ J 2017; 82:1237-1244. [PMID: 28904308 DOI: 10.1253/circj.cj-17-0242] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Aging plays a critical role in the genesis of atrial fibrillation (AF) and also increases the risks of cardiac dysfunction and stroke in AF patients. AF is caused by increased AF triggering from abnormalities of the thoracic vein and/or modulated substrate (atrial) with enhancement of AF maintenance. Clinical and laboratory evidence indicates that aging is significant in the creation of atrial electrical and structural remodeling that leads to increased susceptibility to AF occurrence. Aging is commonly associated with cardiovascular comorbidities, oxidative stress, calcium dysregulation, atrial myopathy with apoptosis, and fibrosis, which all contribute to the genesis of AF. This review updates the current understanding of the effects of aging on the pathophysiology of AF.
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Affiliation(s)
- Yung-Kuo Lin
- Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University.,Division of Cardiology, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University
| | - Yi-Ann Chen
- Division of Nephrology, Sijhih Cathay General Hospital
| | - Ting-I Lee
- Division of Endocrinology and Metabolism, Wan Fang Hospital, Taipei Medical University
| | - Yao-Chang Chen
- Department of Biomedical Engineering, National Defense Medical Center
| | - Shih-Ann Chen
- Division of Cardiology and Cardiovascular Research Center, Veterans General Hospital-Taipei
| | - Yi-Jen Chen
- Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University.,Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University
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220
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Hysteretic Dynamics of Multi-Stable Early Afterdepolarisations with Repolarisation Reserve Attenuation: A Potential Dynamical Mechanism for Cardiac Arrhythmias. Sci Rep 2017; 7:10771. [PMID: 28883639 PMCID: PMC5589958 DOI: 10.1038/s41598-017-11355-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 08/23/2017] [Indexed: 02/08/2023] Open
Abstract
Some cardiovascular and non-cardiovascular drugs frequently cause excessive prolongation of the cardiac action potential (AP) and lead to the development of early afterdepolarisations (EADs), which trigger lethal ventricular arrhythmias. Combining computer simulations in APs with numerical calculations based on dynamical system theory, we investigated stability changes of APs observed in a paced human ventricular myocyte model by decreasing and/or increasing the rapid (IKr) and slow (IKs) components of delayed rectifying K+ current. Upon reducing IKr, the APs without EADs (no-EAD response) showed gradual prolongation of AP duration (APD), and were annihilated without AP configuration changes due to the occurrence of saddle-node bifurcations. This annihilation caused a transition to an AP with EADs as a new stable steady state. Furthermore, reducing repolarisation currents (repolarisation reserve attenuation) evoked multi-stable states consisting of APs with different APDs, and caused multiple hysteretic dynamics. Depending on initial ion circumstances within ventricular myocytes, these multi-stable AP states might increase the local/global heterogeneity of AP repolarisations in the ventricle. Thus, the EAD-induced arrhythmias with repolarisation reserve attenuation might be attributed to the APD variability caused by multi-stability in cardiac AP dynamics.
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221
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Circadian pattern of short-term variability of the QT-interval in primary prevention ICD patients - EU-CERT-ICD methodological pilot study. PLoS One 2017; 12:e0183199. [PMID: 28827816 PMCID: PMC5565185 DOI: 10.1371/journal.pone.0183199] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 07/31/2017] [Indexed: 01/26/2023] Open
Abstract
Objective Short-term variability of the QT-interval (STV-QT) was shown to be associated with an increased risk of ventricular arrhythmias. We aimed at investigating (a) whether STV-QT exhibits circadian pattern, and (b) whether such pattern differs between patients with high and low arrhythmia risk. Methods As part of the ongoing EU-CERT-ICD study, 24h high resolution digital ambulatory 12-lead Holter recordings are collected prior to ICD implantation for primary prophylactic indication. Presently available patients were categorized based on their arrhythmia score (AS), a custom-made weighted score of the number of arrhythmic events on the recording. STV-QT was calculated every hour in 30 patients of which 15 and 15 patients had a high and a low AS, respectively. Results The overall dynamicity of STV-QT showed high intra- and inter-individual variability with different circadian patterns associated with low and high AS. High AS patients showed a prominent peak both at 08:00 and 18:00. At these times, STV-QT was significantly higher in the high AS patients compared to the low AS patients (1.22ms±0.55ms vs 0.60ms±0.24ms at 08:00 and 1.12ms±0.39ms vs 0.64ms±0.29ms at 18:00, both p < 0.01). Conclusion In patients with high AS, STV-QT peaks in the early morning and late afternoon. This potentially reflects increased arrhythmia risk at these times. Prospective STV-QT determination at these times might thus be more sensitive to identify patients at high risk of ventricular arrhythmias.
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222
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Kirschner Peretz N, Segal S, Arbel-Ganon L, Ben Jehuda R, Shemer Y, Eisen B, Davoodi M, Binah O, Yaniv Y. A Method Sustaining the Bioelectric, Biophysical, and Bioenergetic Function of Cultured Rabbit Atrial Cells. Front Physiol 2017; 8:584. [PMID: 28860999 PMCID: PMC5559495 DOI: 10.3389/fphys.2017.00584] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 07/31/2017] [Indexed: 12/16/2022] Open
Abstract
Culturing atrial cells leads to a loss in their ability to be externally paced at physiological rates and to maintain their shape. We aim to develop a culture method that sustains the shape of atrial cells along with their biophysical and bioenergetic properties in response to physiological pacing. We hypothesize that adding 2,3-Butanedione 2-monoxime (BDM), which inhibits contraction during the culture period, will preserve these biophysical and bioenergetic properties. Rabbit atrial cells were maintained in culture for 24 h in a medium enriched with a myofilament contraction inhibitor, BDM. The morphology and volume of the cells, including their ability to contract in response to 1–3 Hz electrical pacing, was maintained at the same level as fresh cells. Importantly, the cells could be successfully infected with a GFP adenovirus. Action potentials, Ca2+ transients, and local Ca2+ spark parameters were similar in the cultured and in fresh cells. Finally, these cultured cells' flavoprotein autofluorescence was maintained at a constant level in response to electrical pacing, a response similar to that of fresh cells. Thus, eliminating contraction during the culture period preserves the bioelectric, biophysical and bioenergetic properties of rabbit atrial myocytes. This method therefore has the potential to further improve our understanding of energetic and biochemical regulation in the atria.
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Affiliation(s)
- Noa Kirschner Peretz
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Sofia Segal
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Limor Arbel-Ganon
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Ronen Ben Jehuda
- Department of Physiology, Biophysics and Systems Biology, Technion - Israel Institute of TechnologyHaifa, Israel.,The Rappaport Institute, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Yuval Shemer
- Department of Physiology, Biophysics and Systems Biology, Technion - Israel Institute of TechnologyHaifa, Israel.,The Rappaport Institute, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Binyamin Eisen
- Department of Physiology, Biophysics and Systems Biology, Technion - Israel Institute of TechnologyHaifa, Israel.,The Rappaport Institute, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Moran Davoodi
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Ofer Binah
- Department of Physiology, Biophysics and Systems Biology, Technion - Israel Institute of TechnologyHaifa, Israel.,The Rappaport Institute, The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of TechnologyHaifa, Israel
| | - Yael Yaniv
- Biomedical Engineering Faculty, Technion - Israel Institute of TechnologyHaifa, Israel
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223
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Kratz JM, Grienke U, Scheel O, Mann SA, Rollinger JM. Natural products modulating the hERG channel: heartaches and hope. Nat Prod Rep 2017; 34:957-980. [PMID: 28497823 PMCID: PMC5708533 DOI: 10.1039/c7np00014f] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
This review covers natural products modulating the hERG potassium channel. Risk assessment strategies, structural features of blockers, and the duality target/antitarget are discussed.
Covering: 1996–December 2016 The human Ether-à-go-go Related Gene (hERG) channel is a voltage-gated potassium channel playing an essential role in the normal electrical activity in the heart. It is involved in the repolarization and termination of action potentials in excitable cardiac cells. Mutations in the hERG gene and hERG channel blockage by small molecules are associated with increased risk of fatal arrhythmias. Several drugs have been withdrawn from the market due to hERG channel-related cardiotoxicity. Moreover, as a result of its notorious ligand promiscuity, this ion channel has emerged as an important antitarget in early drug discovery and development. Surprisingly, the hERG channel blocking profile of natural compounds present in frequently consumed botanicals (i.e. dietary supplements, spices, and herbal medicinal products) is not routinely assessed. This comprehensive review will address these issues and provide a critical compilation of hERG channel data for isolated natural products and extracts over the past two decades (1996–2016). In addition, the review will provide (i) a solid basis for the molecular understanding of the physiological functions of the hERG channel, (ii) the translational potential of in vitro/in vivo results to cardiotoxicity in humans, (iii) approaches for the identification of hERG channel blockers from natural sources, (iv) future perspectives for cardiac safety guidelines and their applications within phytopharmaceuticals and dietary supplements, and (v) novel applications of hERG channel modulation (e.g. as a drug target).
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Affiliation(s)
- Jadel M Kratz
- Department of Pharmacognosy, Faculty of Life Sciences, University of Vienna, Althanstraße 14, 1090 Vienna, Austria.
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Effect of GWAS-Identified Genetic Variants on Maximum QT Interval in Patients With Schizophrenia Receiving Antipsychotic Agents: A 24-Hour Holter ECG Study. J Clin Psychopharmacol 2017; 37:452-455. [PMID: 28590366 DOI: 10.1097/jcp.0000000000000724] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Users of antipsychotics (APs) have a risk of sudden cardiac death (SCD). Sudden cardiac death in such patients is thought to be largely due to drug-induced QT prolongation. It has been reported that many subjects with drug-induced torsades de pointes (TdP) have risk alleles associated with subclinical congenital long QT syndrome. METHODS We investigated the effects of the risk alleles associated with long QT on the QT interval in patients receiving APs using 24-hour Holter electrocardiograms to take into account the circadian fluctuation of QT intervals. We investigated 8 single-nucleotide polymorphisms identified on a GWAS. RESULTS We found that increased numbers of risk alleles at rs7188697 in NDRG4 and rs11970286 in PLN were the major predictors of an increased maximum QT interval over 24 hours in users of APs. CONCLUSIONS It could be useful to perform a DNA-based analysis before the initiation of APs to reduce the risk of drug-induced torsades de pointes and SCD.
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225
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Bondarenko VE, Shilnikov AL. Bursting dynamics in the normal and failing hearts. Sci Rep 2017; 7:5927. [PMID: 28725037 PMCID: PMC5517618 DOI: 10.1038/s41598-017-05198-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 05/15/2017] [Indexed: 01/03/2023] Open
Abstract
A failing heart differs from healthy hearts by an array of symptomatic characteristics, including impaired Ca2+ transients, upregulation of Na+/Ca2+ exchanger function, reduction of Ca2+ uptake to sarcoplasmic reticulum, reduced K+ currents, and increased propensity to arrhythmias. While significant efforts have been made in both experimental studies and model development to display the causes of heart failure, the full process of deterioration from a healthy to a failing heart yet remains deficiently understood. In this paper, we analyze a highly detailed mathematical model of mouse ventricular myocytes to disclose the key mechanisms underlying the continual transition towards a state of heart failure. We argue that such a transition can be described in mathematical terms as a sequence of bifurcations that the healthy cells undergo while transforming into failing cells. They include normal action potentials and [Ca2+]i transients, action potential and [Ca2+]i alternans, and bursting behaviors. These behaviors where supported by experimental studies of heart failure. The analysis of this model allowed us to identify that the slow component of the fast Na+ current is a key determining factor for the onset of bursting activity in mouse ventricular myocytes.
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Affiliation(s)
- Vladimir E Bondarenko
- Department of Mathematics and Statistics and Neuroscience Institute, Georgia State University, 30 Pryor Street, Atlanta, GA 30303, United States.
| | - Andrey L Shilnikov
- Department of Mathematics and Statistics and Neuroscience Institute, Georgia State University, 30 Pryor Street, Atlanta, GA 30303, United States.,Institute for Information Technologies, Mathematics and Mechanics, Nizhni Novgorod State University, Gagarin Av. 23, 606950, Nizhni Novgorod, Russia
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226
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Loss of MD1 exacerbates pressure overload-induced left ventricular structural and electrical remodelling. Sci Rep 2017; 7:5116. [PMID: 28698617 PMCID: PMC5505950 DOI: 10.1038/s41598-017-05379-w] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 05/30/2017] [Indexed: 12/24/2022] Open
Abstract
Myeloid differentiation protein 1 (MD1) has been implicated in numerous pathophysiological processes, including immune regulation, obesity, insulin resistance, and inflammation. However, the role of MD1 in cardiac remodelling remains incompletely understood. We used MD1-knockout (KO) mice and their wild-type littermates to determine the functional significance of MD1 in the regulation of aortic banding (AB)-induced left ventricular (LV) structural and electrical remodelling and its underlying mechanisms. After 4 weeks of AB, MD1-KO hearts showed substantial aggravation of LV hypertrophy, fibrosis, LV dilation and dysfunction, and electrical remodelling, which resulted in overt heart failure and increased electrophysiological instability. Moreover, MD1-KO-AB cardiomyocytes showed increased diastolic sarcoplasmic reticulum (SR) Ca2+ leak, reduced Ca2+ transient amplitude and SR Ca2+ content, decreased SR Ca2+-ATPase2 expression, and increased phospholamban and Na+/Ca2+-exchanger 1 protein expression. Mechanistically, the adverse effects of MD1 deletion on LV remodelling were related to hyperactivated CaMKII signalling and increased impairment of intracellular Ca2+ homeostasis, whereas the increased electrophysiological instability was partly attributed to exaggerated prolongation of cardiac repolarisation, decreased action potential duration alternans threshold, and increased diastolic SR Ca2+ leak. Therefore, our study on MD1 could provide new therapeutic strategies for preventing/treating heart failure.
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227
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Kurtzwald-Josefson E, Yadin D, Harun-Khun S, Waldman M, Aravot D, Shainberg A, Eldar M, Hochhauser E, Arad M. Viral delivered gene therapy to treat catecholaminergic polymorphic ventricular tachycardia (CPVT2) in mouse models. Heart Rhythm 2017; 14:1053-1060. [DOI: 10.1016/j.hrthm.2017.03.025] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Indexed: 11/27/2022]
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228
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Osadchii OE. Role of abnormal repolarization in the mechanism of cardiac arrhythmia. Acta Physiol (Oxf) 2017; 220 Suppl 712:1-71. [PMID: 28707396 DOI: 10.1111/apha.12902] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In cardiac patients, life-threatening tachyarrhythmia is often precipitated by abnormal changes in ventricular repolarization and refractoriness. Repolarization abnormalities typically evolve as a consequence of impaired function of outward K+ currents in cardiac myocytes, which may be caused by genetic defects or result from various acquired pathophysiological conditions, including electrical remodelling in cardiac disease, ion channel modulation by clinically used pharmacological agents, and systemic electrolyte disorders seen in heart failure, such as hypokalaemia. Cardiac electrical instability attributed to abnormal repolarization relies on the complex interplay between a provocative arrhythmic trigger and vulnerable arrhythmic substrate, with a central role played by the excessive prolongation of ventricular action potential duration, impaired intracellular Ca2+ handling, and slowed impulse conduction. This review outlines the electrical activity of ventricular myocytes in normal conditions and cardiac disease, describes classical electrophysiological mechanisms of cardiac arrhythmia, and provides an update on repolarization-related surrogates currently used to assess arrhythmic propensity, including spatial dispersion of repolarization, activation-repolarization coupling, electrical restitution, TRIaD (triangulation, reverse use dependence, instability, and dispersion), and the electromechanical window. This is followed by a discussion of the mechanisms that account for the dependence of arrhythmic vulnerability on the location of the ventricular pacing site. Finally, the review clarifies the electrophysiological basis for cardiac arrhythmia produced by hypokalaemia, and gives insight into the clinical importance and pathophysiology of drug-induced arrhythmia, with particular focus on class Ia (quinidine, procainamide) and Ic (flecainide) Na+ channel blockers, and class III antiarrhythmic agents that block the delayed rectifier K+ channel (dofetilide).
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Affiliation(s)
- O. E. Osadchii
- Department of Health Science and Technology; University of Aalborg; Aalborg Denmark
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229
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Liu W, Chen P, Deng J, Lv J, Liu J. Resveratrol and polydatin as modulators of Ca 2+ mobilization in the cardiovascular system. Ann N Y Acad Sci 2017; 1403:82-91. [PMID: 28665033 DOI: 10.1111/nyas.13386] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 04/20/2017] [Accepted: 04/21/2017] [Indexed: 12/29/2022]
Abstract
In the cardiovascular system, Ca2+ controls cardiac excitation-contraction coupling and vascular contraction and dilation. Disturbances in intracellular Ca2+ homeostasis induce malfunctions of the cardiovascular system, including cardiac pump dysfunction, arrhythmia, remodeling, and apoptosis, as well as hypertension and impairment of vascular reactivity. Therefore, developing drugs and strategies manipulating Ca2+ handling are highly valued in the treatment of cardiovascular disease. Resveratrol (Res) and polydatin (PD), a Res glucoside, have been well established to have beneficial effects on improving cardiovascular function. Studies from our laboratory and others have demonstrated that they exhibit inotropic effects on normal heart and therapeutic effects on hypertension, cardiac ischemia/reperfusion injury, hypertrophy, and heart failure by manipulating Ca2+ mobilization. The actions of Res and PD on Ca2+ signals delicately manipulated by multiple Ca2+ -handling proteins are pleiotropic and somewhat controversial, depending on cellular species and intracellular oxidative status. Here, we focus on the effects of Res and PD on controlling Ca2+ homeostasis in the heart and vasculature under normal and diseased conditions and highlight the key direct and indirect molecules mediating these effects.
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Affiliation(s)
- Wenjuan Liu
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China
| | - Peiya Chen
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China
| | - Jianxin Deng
- Department of Endocrinology, the First Affiliated Hospital of Shenzhen University, Shenzhen University, Shenzhen, China.,Department of Endocrinology, Shenzhen No. 2 People's Hospital, Shenzhen, China
| | - Jingzhang Lv
- Shenzhen Entry-Exit Inspection and Quarantine Bureau, Shenzhen, China
| | - Jie Liu
- Department of Pathophysiology, School of Medicine, Shenzhen University, Shenzhen, China
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230
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Troupes CD, Wallner M, Borghetti G, Zhang C, Mohsin S, von Lewinski D, Berretta RM, Kubo H, Chen X, Soboloff J, Houser S. Role of STIM1 (Stromal Interaction Molecule 1) in Hypertrophy-Related Contractile Dysfunction. Circ Res 2017; 121:125-136. [PMID: 28592415 DOI: 10.1161/circresaha.117.311094] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 06/02/2017] [Accepted: 06/07/2017] [Indexed: 12/20/2022]
Abstract
RATIONALE Pathological increases in cardiac afterload result in myocyte hypertrophy with changes in myocyte electrical and mechanical phenotype. Remodeling of contractile and signaling Ca2+ occurs in pathological hypertrophy and is central to myocyte remodeling. STIM1 (stromal interaction molecule 1) regulates Ca2+ signaling in many cell types by sensing low endoplasmic reticular Ca2+ levels and then coupling to plasma membrane Orai channels to induce a Ca2+ influx pathway. Previous reports suggest that STIM1 may play a role in cardiac hypertrophy, but its role in electrical and mechanical phenotypic alterations is not well understood. OBJECTIVE To define the contributions of STIM1-mediated Ca2+ influx on electrical and mechanical properties of normal and diseased myocytes, and to determine whether Orai channels are obligatory partners for STIM1 in these processes using a clinically relevant large animal model of hypertrophy. METHODS AND RESULTS Cardiac hypertrophy was induced by slow progressive pressure overload in adult cats. Hypertrophied myocytes had increased STIM1 expression and activity, which correlated with altered Ca2+-handling and action potential (AP) prolongation. Exposure of hypertrophied myocytes to the Orai channel blocker BTP2 caused a reduction of AP duration and reduced diastolic Ca2+ spark rate. BTP2 had no effect on normal myocytes. Forced expression of STIM1 in cultured adult feline ventricular myocytes increased diastolic spark rate and prolonged AP duration. STIM1 expression produced an increase in the amount of Ca2+ stored within the sarcoplasmic reticulum and activated Ca2+/calmodulin-dependent protein kinase II. STIM1 expression also increased spark rates and induced spontaneous APs. STIM1 effects were eliminated by either BTP2 or by coexpression of a dominant negative Orai construct. CONCLUSIONS STIM1 can associate with Orai in cardiac myocytes to produce a Ca2+ influx pathway that can prolong the AP duration and load the sarcoplasmic reticulum and likely contributes to the altered electromechanical properties of the hypertrophied heart.
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Affiliation(s)
- Constantine D Troupes
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Markus Wallner
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Giulia Borghetti
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Chen Zhang
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Sadia Mohsin
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Dirk von Lewinski
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Remus M Berretta
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Hajime Kubo
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Xiongwen Chen
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Jonathan Soboloff
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.)
| | - Steven Houser
- From the Cardiovascular Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA (C.D.T., M.W., G.B., C.Z., S.M., R.M.B., H.K., X.C., S.H.); Department of Cardiology, Medical University of Graz, Austria (D.v.L.); and Fels Institute for Cancer Research and Molecular Biology, Lewis Katz School of Medicine, Temple University School of Medicine, Philadelphia, PA (J.S.).
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231
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Ávila P, Chaix MA, Mondésert B, Khairy P. Sudden Cardiac Death in Adult Congenital Heart Disease. Card Electrophysiol Clin 2017; 9:225-234. [PMID: 28457237 DOI: 10.1016/j.ccep.2017.02.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Sudden death of presumed arrhythmic etiology is a leading cause of mortality in adults with congenital heart disease. Anticipated benefits of the implantable cardioverter-defibrillator (ICD) must be weighed against high complication rates. Without robust evidence from randomized trials, caregivers face difficult decisions in selecting appropriate candidates. Although secondary prevention indications are often clear-cut, risk stratification for primary prevention ICDs is more challenging. Factors associated with sudden death in patients with tetralogy of Fallot are reasonably consistent across studies. In contrast, identification of high-risk patients with systemic right ventricles or univentricular hearts remains controversial.
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Affiliation(s)
- Pablo Ávila
- Department of Cardiology, Instituto de Investigación Sanitaria, Hospital Gregorio Marañón, Universidad Complutense, Madrid, Spain
| | - Marie-A Chaix
- Adult Congenital Heart Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger Street East, Montreal H1T 1C8, Canada
| | - Blandine Mondésert
- Adult Congenital Heart Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger Street East, Montreal H1T 1C8, Canada
| | - Paul Khairy
- Adult Congenital Heart Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger Street East, Montreal H1T 1C8, Canada.
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232
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Porter B, Bishop MJ, Claridge S, Behar J, Sieniewicz BJ, Webb J, Gould J, O'Neill M, Rinaldi CA, Razavi R, Gill JS, Taggart P. Autonomic Modulation in Patients with Heart Failure Increases Beat-to-Beat Variability of Ventricular Action Potential Duration. Front Physiol 2017; 8:328. [PMID: 28611676 PMCID: PMC5447044 DOI: 10.3389/fphys.2017.00328] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 05/05/2017] [Indexed: 12/19/2022] Open
Abstract
Background: Exaggerated beat-to-beat variability of ventricular action potential duration (APD) is linked to arrhythmogenesis. Sympathetic stimulation has been shown to increase QT interval variability, but its effect on ventricular APD in humans has not been determined. Methods and Results: Eleven heart failure patients with implanted bi-ventricular pacing devices had activation–recovery intervals (ARI, surrogate for APD) recorded from LV epicardial electrodes under constant RV pacing. Sympathetic activity was increased using a standard autonomic challenge (Valsalva) and baroreceptor indices were applied to determine changes in sympathetic stimulation. Two Valsalvas were performed for each study and were repeated, both off and on bisoprolol. In addition sympathetic nerve activity (SNA) was measured from skin electrodes on the thorax using a novel validated method. Autonomic modulation significantly increased mean short-term variability in ARI; off bisoprolol mean STV increased from 3.73 ± 1.3 to 5.27 ± 1.04 ms (p = 0.01), on bisoprolol mean STV of ARI increased from 4.15 ± 1.14 to 4.62 ± 1 ms (p = 0.14). Adrenergic indices of the Valsalva demonstrated significantly reduced beta-adrenergic function when on bisoprolol (Δ pressure recovery time, p = 0.04; Δ systolic overshoot in Phase IV, p = 0.05). Corresponding increases in SNA from rest both off (1.4 uV, p < 0.01) and on (0.7 uV, p < 0.01) bisoprolol were also seen. Conclusions: Beat-to-beat variability of ventricular APD increases during brief periods of increased sympathetic activity in patients with heart failure. Bisoprolol reduces, but does not eliminate, these effects. This may be important in the genesis of ventricular arrhythmias in heart failure patients.
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Affiliation(s)
- Bradley Porter
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Martin J Bishop
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Simon Claridge
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Jonathan Behar
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Benjamin J Sieniewicz
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Jessica Webb
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Justin Gould
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Mark O'Neill
- Cardiology Department, Guy's and St. Thomas' HospitalLondon, United Kingdom
| | | | - Reza Razavi
- Department of Imaging Sciences and Biomedical Engineering, Kings College LondonLondon, United Kingdom
| | - Jaswinder S Gill
- Cardiology Department, Guy's and St. Thomas' HospitalLondon, United Kingdom
| | - Peter Taggart
- Department of Cardiovascular Sciences, University College LondonLondon, United Kingdom
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Gómez-Hurtado N, Domínguez-Rodríguez A, Mateo P, Fernández-Velasco M, Val-Blasco A, Aizpún R, Sabourin J, Gómez AM, Benitah JP, Delgado C. Beneficial effects of leptin treatment in a setting of cardiac dysfunction induced by transverse aortic constriction in mouse. J Physiol 2017; 595:4227-4243. [PMID: 28374413 DOI: 10.1113/jp274030] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 03/20/2017] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Leptin, is a 16 kDa pleiotropic peptide not only primarily secreted by adipocytes, but also produced by other tissues, including the heart. Controversy exists regarding the adverse and beneficial effects of leptin on the heart We analysed the effect of a non-hypertensive dose of leptin on cardiac function, [Ca2+ ]i handling and cellular electrophysiology, which participate in the genesis of pump failure and related arrhythmias, both in control mice and in mice subjected to chronic pressure-overload by transverse aorta constriction. We find that leptin activates mechanisms that contribute to cardiac dysfunction under physiological conditions. However, after the establishment of pressure overload, an increase in leptin levels has protective cardiac effects with respect to rescuing the cellular heart failure phenotype. These beneficial effects of leptin involve restoration of action potential duration via normalization of transient outward potassium current and sarcoplasmic reticulum Ca2+ content via rescue of control sarcoplasmic/endoplasmic reticulum Ca2+ ATPase levels and ryanodine receptor function modulation, leading to normalization of Ca2+ handling parameters. ABSTRACT Leptin, is a 16 kDa pleiotropic peptide not only primary secreted by adipocytes, but also produced by other tissues, including the heart. Evidence indicates that leptin may have either adverse or beneficial effects on the heart. To obtain further insights, in the present study, we analysed the effect of leptin treatment on cardiac function, [Ca2+ ]i handling and cellular electrophysiology, which participate in the genesis of pump failure and related arrhythmias, both in control mice and in mice subjected to chronic pressure-overload by transverse aorta constriction (TAC). Three weeks after surgery, animals received either leptin (0.36 mg kg-1 day-1 ) or vehicle via osmotic minipumps for 3 weeks. Echocardiographic measurements showed that, although leptin treatment was deleterious on cardiac function in sham, leptin had a cardioprotective effect following TAC. [Ca2+ ]i transient in cardiomyocytes followed similar pattern. Patch clamp experiments showed prolongation of action potential duration (APD) in TAC and leptin-treated sham animals, whereas, following TAC, leptin reduced the APD towards control values. APD variations were associated with decreased transient outward potassium current and Kv4.2 and KChIP2 protein expression. TAC myocytes showed a higher incidence of triggered activities and spontaneous Ca2+ waves. These proarrhythmic manifestations, related to Ca2+ /calmodulin-dependent protein kinase II and ryanodine receptor phosphorylation, were reduced by leptin. The results of the present study demonstrate that, although leptin treatment was deleterious on cardiac function in control animals, leptin had a cardioprotective effect following TAC, normalizing cardiac function and reducing arrhythmogeneity at the cellular level.
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Affiliation(s)
- Nieves Gómez-Hurtado
- Departament of Pharmacology, School of Medicine, Complutense University, Madrid, Spain.,UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France.,Division of Clinical Pharmacology, Oates Institute for Experimental Therapeutics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Alejandro Domínguez-Rodríguez
- UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France.,Institute of Biomedicine of Seville/CIBER-CV, Seville, Spain
| | - Philippe Mateo
- UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | | | | | - Rafael Aizpún
- Departament of Pharmacology, School of Medicine, Complutense University, Madrid, Spain
| | - Jessica Sabourin
- UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | - Ana María Gómez
- UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | - Jean-Pierre Benitah
- UMR-S 1180, Inserm, Univ. Paris-Sud, Université Paris-Saclay, Châtenay-Malabry, France
| | - Carmen Delgado
- Departament of Pharmacology, School of Medicine, Complutense University, Madrid, Spain.,Biomedical Research Institute Alberto Sols/CIBER-CV, Madrid, Spain
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Exclusion of alternative exon 33 of Ca V1.2 calcium channels in heart is proarrhythmogenic. Proc Natl Acad Sci U S A 2017; 114:E4288-E4295. [PMID: 28490495 DOI: 10.1073/pnas.1617205114] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Alternative splicing changes the CaV1.2 calcium channel electrophysiological property, but the in vivo significance of such altered channel function is lacking. Structure-function studies of heterologously expressed CaV1.2 channels could not recapitulate channel function in the native milieu of the cardiomyocyte. To address this gap in knowledge, we investigated the role of alternative exon 33 of the CaV1.2 calcium channel in heart function. Exclusion of exon 33 in CaV1.2 channels has been reported to shift the activation potential -10.4 mV to the hyperpolarized direction, and increased expression of CaV1.2Δ33 channels was observed in rat myocardial infarcted hearts. However, how a change in CaV1.2 channel electrophysiological property, due to alternative splicing, might affect cardiac function in vivo is unknown. To address these questions, we generated mCacna1c exon 33-/--null mice. These mice contained CaV1.2Δ33 channels with a gain-of-function that included conduction of larger currents that reflects a shift in voltage dependence and a modest increase in single-channel open probability. This altered channel property underscored the development of ventricular arrhythmia, which is reflected in significantly more deaths of exon 33-/- mice from β-adrenergic stimulation. In vivo telemetric recordings also confirmed increased frequencies in premature ventricular contractions, tachycardia, and lengthened QT interval. Taken together, the significant decrease or absence of exon 33-containing CaV1.2 channels is potentially proarrhythmic in the heart. Of clinical relevance, human ischemic and dilated cardiomyopathy hearts showed increased inclusion of exon 33. However, the possible role that inclusion of exon 33 in CaV1.2 channels may play in the pathogenesis of human heart failure remains unclear.
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235
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Britton OJ, Bueno-Orovio A, Virág L, Varró A, Rodriguez B. The Electrogenic Na +/K + Pump Is a Key Determinant of Repolarization Abnormality Susceptibility in Human Ventricular Cardiomyocytes: A Population-Based Simulation Study. Front Physiol 2017; 8:278. [PMID: 28529489 PMCID: PMC5418229 DOI: 10.3389/fphys.2017.00278] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 04/18/2017] [Indexed: 11/23/2022] Open
Abstract
Background: Cellular repolarization abnormalities occur unpredictably due to disease and drug effects, and can occur even in cardiomyocytes that exhibit normal action potentials (AP) under control conditions. Variability in ion channel densities may explain differences in this susceptibility to repolarization abnormalities. Here, we quantify the importance of key ionic mechanisms determining repolarization abnormalities following ionic block in human cardiomyocytes yielding normal APs under control conditions. Methods and Results: Sixty two AP recordings from non-diseased human heart preparations were used to construct a population of human ventricular models with normal APs and a wide range of ion channel densities. Multichannel ionic block was applied to investigate susceptibility to repolarization abnormalities. IKr block was necessary for the development of repolarization abnormalities. Models that developed repolarization abnormalities over the widest range of blocks possessed low Na+/K+ pump conductance below 50% of baseline, and ICaL conductance above 70% of baseline. Furthermore, INaK made the second largest contribution to repolarizing current in control simulations and the largest contribution under 75% IKr block. Reversing intracellular Na+ overload caused by reduced INaK was not sufficient to prevent abnormalities in models with low Na+/K+ pump conductance, while returning Na+/K+ pump conductance to normal substantially reduced abnormality occurrence, indicating INaK is an important repolarization current. Conclusions: INaK is an important determinant of repolarization abnormality susceptibility in human ventricular cardiomyocytes, through its contribution to repolarization current rather than homeostasis. While we found IKr block to be necessary for repolarization abnormalities to occur, INaK decrease, as in disease, may amplify the pro-arrhythmic risk of drug-induced IKr block in humans.
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Affiliation(s)
| | | | - László Virág
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of SzegedSzeged, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of SzegedSzeged, Hungary
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236
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Rozier K, Bondarenko VE. Distinct physiological effects of β1- and β2-adrenoceptors in mouse ventricular myocytes: insights from a compartmentalized mathematical model. Am J Physiol Cell Physiol 2017; 312:C595-C623. [DOI: 10.1152/ajpcell.00273.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 01/03/2017] [Accepted: 01/18/2017] [Indexed: 01/08/2023]
Abstract
The β1- and β2-adrenergic signaling systems play different roles in the functioning of cardiac cells. Experimental data show that the activation of the β1-adrenergic signaling system produces significant inotropic, lusitropic, and chronotropic effects in the heart, whereas the effects of the β2-adrenergic signaling system is less apparent. In this paper, a comprehensive compartmentalized experimentally based mathematical model of the combined β1- and β2-adrenergic signaling systems in mouse ventricular myocytes is developed to simulate the experimental findings and make testable predictions of the behavior of the cardiac cells under different physiological conditions. Simulations describe the dynamics of major signaling molecules in different subcellular compartments; kinetics and magnitudes of phosphorylation of ion channels, transporters, and Ca2+ handling proteins; modifications of action potential shape and duration; and [Ca2+]i and [Na+]i dynamics upon stimulation of β1- and β2-adrenergic receptors (β1- and β2-ARs). The model reveals physiological conditions when β2-ARs do not produce significant physiological effects and when their effects can be measured experimentally. Simulations demonstrated that stimulation of β2-ARs with isoproterenol caused a marked increase in the magnitude of the L-type Ca2+ current, [Ca2+]i transient, and phosphorylation of phospholamban only upon additional application of pertussis toxin or inhibition of phosphodiesterases of type 3 and 4. The model also made testable predictions of the changes in magnitudes of [Ca2+]i and [Na+]i fluxes, the rate of decay of [Na+]i concentration upon both combined and separate stimulation of β1- and β2-ARs, and the contribution of phosphorylation of PKA targets to the changes in the action potential and [Ca2+]i transient.
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Affiliation(s)
- Kelvin Rozier
- Department of Mathematics and Statistics, Georgia State University, Atlanta, Georgia; and
| | - Vladimir E. Bondarenko
- Department of Mathematics and Statistics, Georgia State University, Atlanta, Georgia; and
- Neuroscience Institute, Georgia State University, Atlanta, Georgia
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237
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Calcium dynamics in cardiac excitatory and non-excitatory cells and the role of gap junction. Math Biosci 2017; 289:51-68. [PMID: 28457965 DOI: 10.1016/j.mbs.2017.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2016] [Revised: 11/12/2016] [Accepted: 04/26/2017] [Indexed: 11/21/2022]
Abstract
Calcium ions aid in the generation of action potential in myocytes and are responsible for the excitation-contraction coupling of heart. The heart muscle has specialized patches of cells, called excitatory cells (EC) such as the Sino-atrial node cells capable of auto-generation of action potential and cells which receive signals from the excitatory cells, called non-excitatory cells (NEC) such as cells of the ventricular and auricular walls. In order to understand cardiac calcium homeostasis, it is, therefore, important to study the calcium dynamics taking into account both types of cardiac cells. Here we have developed a model to capture the calcium dynamics in excitatory and non-excitatory cells taking into consideration the gap junction mediated calcium ion transfer from excitatory cell to non-excitatory cell. Our study revealed that the gap junctional coupling between excitatory and non-excitatory cells plays important role in the calcium dynamics. It is observed that any reduction in the functioning of gap junction may result in abnormal calcium oscillations in NEC, even when the calcium dynamics is normal in EC cell. Sensitivity of gap junction is observed to be independent of the pacing rate and hence a careful monitoring is required to maintain normal cardiomyocyte condition. It also highlights that sarcoplasmic reticulum may not be always able to control the amount of cytoplasmic calcium under the condition of calcium overload.
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238
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Klein MG, Shou M, Stohlman J, Solhjoo S, Haigney M, Tidwell RR, Goldstein RE, Flagg TP, Haigney MC. Role of suppression of the inward rectifier current in terminal action potential repolarization in the failing heart. Heart Rhythm 2017; 14:1217-1223. [PMID: 28396172 DOI: 10.1016/j.hrthm.2017.04.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Indexed: 11/19/2022]
Abstract
BACKGROUND The failing heart exhibits an increased arrhythmia susceptibility that is often attributed to action potential (AP) prolongation due to significant ion channel remodeling. The inwardly rectifying K+ current (IK1) has been reported to be reduced, but its contribution to shaping the AP waveform and cell excitability in the failing heart remains unclear. OBJECTIVE The purpose of this study was to define the effect of IK1 suppression on the cardiac AP and excitability in the normal and failing hearts. METHODS We used electrophysiological and pharmacological approaches to investigate IK1 function in a swine tachy-pacing model of heart failure (HF). RESULTS Terminal repolarization of the AP (TRAP; the time constant of the exponential fit to terminal repolarization) was markedly prolonged in both myocytes and arterially perfused wedges from animals with HF. TRAP was increased by 54.1% in HF myocytes (P < .001) and 26.2% in HF wedges (P = .014). The increase in TRAP was recapitulated by the potent and specific IK1 inhibitor, PA-6 (pentamidine analog 6), indicating that IK1 is the primary determinant of the final phase of repolarization. Moreover, we find that IK1 suppression reduced the ratio of effective refractory period to AP duration at 90% of repolarization, permitting re-excitation before full repolarization, reduction of AP upstroke velocity, and likely promotion of slow conduction. CONCLUSION Using an objective measure of terminal repolarization, we conclude that IK1 is the major determinant of the terminal repolarization time course. Moreover, suppression of IK1 prolongs repolarization and reduces postrepolarization refractoriness without marked effects on the overall AP duration. Collectively, these findings demonstrate how IK1 suppression may contribute to arrhythmogenesis in the failing heart.
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Affiliation(s)
- Michael G Klein
- Division of Cardiology, Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.
| | - Matie Shou
- Division of Cardiology, Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Jayna Stohlman
- Center for Devices and Radiological Health, Food and Drug Administration, Silver Spring, Maryland
| | - Soroosh Solhjoo
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Myles Haigney
- Division of Cardiology, Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Richard R Tidwell
- Department of Pathology and Laboratory Medicine, School of Medicine, The University of North Carolina, Chapel Hill, North Carolina
| | - Robert E Goldstein
- Division of Cardiology, Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Thomas P Flagg
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Mark C Haigney
- Division of Cardiology, Department of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland
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239
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Novel insight into arrhythmogenic remodeling: a target for reversal. Hypertens Res 2017; 40:632-634. [PMID: 28381871 DOI: 10.1038/hr.2017.46] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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240
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Klassen MP, Peters CJ, Zhou S, Williams HH, Jan LY, Jan YN. Age-dependent diastolic heart failure in an in vivo Drosophila model. eLife 2017; 6. [PMID: 28328397 PMCID: PMC5362267 DOI: 10.7554/elife.20851] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 02/11/2017] [Indexed: 12/13/2022] Open
Abstract
While the signals and complexes that coordinate the heartbeat are well established, how the heart maintains its electromechanical rhythm over a lifetime remains an open question with significant implications to human health. Reasoning that this homeostatic challenge confronts all pulsatile organs, we developed a high resolution imaging and analysis toolset for measuring cardiac function in intact, unanesthetized Drosophila melanogaster. We demonstrate that, as in humans, normal aging primarily manifests as defects in relaxation (diastole) while preserving contractile performance. Using this approach, we discovered that a pair of two-pore potassium channel (K2P) subunits, largely dispensable early in life, are necessary for terminating contraction (systole) in aged animals, where their loss culminates in fibrillatory cardiac arrest. As the pumping function of its heart is acutely dispensable for survival, Drosophila represents a uniquely accessible model for understanding the signaling networks maintaining cardiac performance during normal aging.
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Affiliation(s)
- Matthew P Klassen
- Department of Physiology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
| | - Christian J Peters
- Department of Physiology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
| | - Shiwei Zhou
- Department of Physiology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
| | - Hannah H Williams
- Department of Physiology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
| | - Lily Yeh Jan
- Department of Physiology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States.,Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
| | - Yuh Nung Jan
- Department of Physiology, Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, United States
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Nassal DM, Wan X, Liu H, Maleski D, Ramirez-Navarro A, Moravec CS, Ficker E, Laurita KR, Deschênes I. KChIP2 is a core transcriptional regulator of cardiac excitability. eLife 2017; 6. [PMID: 28263709 PMCID: PMC5338919 DOI: 10.7554/elife.17304] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 02/19/2017] [Indexed: 11/18/2022] Open
Abstract
Arrhythmogenesis from aberrant electrical remodeling is a primary cause of death among patients with heart disease. Amongst a multitude of remodeling events, reduced expression of the ion channel subunit KChIP2 is consistently observed in numerous cardiac pathologies. However, it remains unknown if KChIP2 loss is merely a symptom or involved in disease development. Using rat and human derived cardiomyocytes, we identify a previously unobserved transcriptional capacity for cardiac KChIP2 critical in maintaining electrical stability. Through interaction with genetic elements, KChIP2 transcriptionally repressed the miRNAs miR-34b and miR-34c, which subsequently targeted key depolarizing (INa) and repolarizing (Ito) currents altered in cardiac disease. Genetically maintaining KChIP2 expression or inhibiting miR-34 under pathologic conditions restored channel function and moreover, prevented the incidence of reentrant arrhythmias. This identifies the KChIP2/miR-34 axis as a central regulator in developing electrical dysfunction and reveals miR-34 as a therapeutic target for treating arrhythmogenesis in heart disease. DOI:http://dx.doi.org/10.7554/eLife.17304.001 The heart pumps blood throughout the body to provide oxygen and nourishment. To do so, proteins in the heart create electrical signals that tell the heart muscles to contract in a coordinated manner. Heart disease can cause cells to lose control of the production or activity of these proteins, creating disorganized electrical signals called arrhythmias that interfere with the heart’s ability to pump. Sometimes these arrhythmias lead to sudden death. Researchers do not know exactly what triggers these changes in the heart’s normal electrical rhythms. This has made it difficult to develop strategies to prevent these disruptions or to fix them when they occur. By studying rat and human heart cells, Nassal et al. now show that a protein called KChIP2 stops working properly during heart disease. Most importantly, because of the decreased level of KChIP2 in heart disease, KChIP2 loses the ability to restrict the production of two microRNA molecules – a role that KChIP2 was not previously known to perform. This loss of activity sets off a cascade of signals that worsens the balance of electrical activity in the heart cells, creating arrhythmias. Treatments that restored proper levels of the fully working KChIP2 protein to the heart cells or that blocked the signals set off by a lack of KChIP2 returned the electrical activity of the cells back to normal. This also stopped the development of arrhythmias. Further studies are now needed to investigate whether these treatments have the same effects in living mammals. If effective, this could ultimately lead to new treatments for heart diseases and arrhythmias. DOI:http://dx.doi.org/10.7554/eLife.17304.002
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Affiliation(s)
- Drew M Nassal
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States.,Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, United States
| | - Xiaoping Wan
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States
| | - Haiyan Liu
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States
| | - Danielle Maleski
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States
| | - Angelina Ramirez-Navarro
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States
| | - Christine S Moravec
- Department of Molecular Cardiology, Cleveland Clinic, Cleveland, United States
| | - Eckhard Ficker
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States
| | - Kenneth R Laurita
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States
| | - Isabelle Deschênes
- Heart and Vascular Research Center, Department of Medicine, Case Western Reserve University, Cleveland, United States.,Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, United States
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243
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Inhibition and inactivation of human CYP2J2: Implications in cardiac pathophysiology and opportunities in cancer therapy. Biochem Pharmacol 2017; 135:12-21. [PMID: 28237650 DOI: 10.1016/j.bcp.2017.02.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 02/21/2017] [Indexed: 12/15/2022]
Abstract
Extrahepatic cytochrome P450 enzymes (CYP450) are pivotal in the metabolism of endogenous substrates and xenobiotics. CYP2J2 is a major cardiac CYP450 and primarily metabolizes polyunsaturated fatty acids such as arachidonic acid to cardioactive epoxyeicosatrienoic acids. Due to its role in endobiotic metabolism, CYP2J2 has been actively studied in recent years with the focus on its biological functions in cardiac pathophysiology. Additionally, CYP2J2 metabolizes a number of xenobiotics such as astemizole and terfenadine and is potently inhibited by danazol and telmisartan. Notably, CYP2J2 is found to be upregulated in multiple cancers. Hence a number of specific CYP2J2 inhibitors have been developed and their efficacy in inhibiting tumor progression has been actively studied. CYP2J2 inhibitor such as C26 (1-[4-(vinyl)phenyl]-4-[4-(diphenyl-hydroxymethyl)-piperidinyl]-butanone hydrochloride) caused marked reduction in tumor proliferation and migration as well as promoted apoptosis in cancer cells. In this review, we discuss the role of CYP2J2 in cardiac pathophysiology and cancer therapeutics. Additionally, we provide an update on the substrates, reversible inhibitors and irreversible inhibitors of CYP2J2. Finally, we discuss the current gaps and future directions in CYP2J2 research.
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244
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Automated Classification of Severity in Cardiac Dyssynchrony Merging Clinical Data and Mechanical Descriptors. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2017; 2017:3087407. [PMID: 28348637 PMCID: PMC5350313 DOI: 10.1155/2017/3087407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 12/18/2016] [Accepted: 01/23/2017] [Indexed: 12/28/2022]
Abstract
Cardiac resynchronization therapy (CRT) improves functional classification among patients with left ventricle malfunction and ventricular electric conduction disorders. However, a high percentage of subjects under CRT (20%–30%) do not show any improvement. Nonetheless the presence of mechanical contraction dyssynchrony in ventricles has been proposed as an indicator of CRT response. This work proposes an automated classification model of severity in ventricular contraction dyssynchrony. The model includes clinical data such as left ventricular ejection fraction (LVEF), QRS and P-R intervals, and the 3 most significant factors extracted from the factor analysis of dynamic structures applied to a set of equilibrium radionuclide angiography images representing the mechanical behavior of cardiac contraction. A control group of 33 normal volunteers (28 ± 5 years, LVEF of 59.7% ± 5.8%) and a HF group of 42 subjects (53.12 ± 15.05 years, LVEF < 35%) were studied. The proposed classifiers had hit rates of 90%, 50%, and 80% to distinguish between absent, mild, and moderate-severe interventricular dyssynchrony, respectively. For intraventricular dyssynchrony, hit rates of 100%, 50%, and 90% were observed distinguishing between absent, mild, and moderate-severe, respectively. These results seem promising in using this automated method for clinical follow-up of patients undergoing CRT.
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245
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Inhibitory effects of cholinesterase inhibitor donepezil on the Kv1.5 potassium channel. Sci Rep 2017; 7:41509. [PMID: 28198801 PMCID: PMC5304190 DOI: 10.1038/srep41509] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 12/21/2016] [Indexed: 11/25/2022] Open
Abstract
Kv1.5 channels carry ultra-rapid delayed rectifier K+ currents in excitable cells, including neurons and cardiac myocytes. In the current study, the effects of cholinesterase inhibitor donepezil on cloned Kv1.5 channels expressed in HEK29 cells were explored using whole-cell recording technique. Exposure to donepezil resulted in a rapid and reversible block of Kv1.5 currents, with an IC50 value of 72.5 μM. The mutant R476V significantly reduced the binding affinity of donepezil to Kv1.5 channels, showing the target site in the outer mouth region. Donepezil produced a significant delay in the duration of activation and deactivation, and mutant R476V potentiated these effects without altering activation curves. In response to slowed deactivation time course, a typical crossover of Kv1.5 tail currents was clearly evident after bath application of donepezil. In addition, both this chemical and mutant R476V accelerated current decay during channel inactivation in a voltage-dependent way, but barely changed the inactivation and recovery curves. The presence of donepezil exhibited the use-dependent block of Kv1.5 currents in response to a series of depolarizing pulses. Our data indicate that donepezil can directly block Kv1.5 channels in its open and closed states.
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246
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Cdon deficiency causes cardiac remodeling through hyperactivation of WNT/β-catenin signaling. Proc Natl Acad Sci U S A 2017; 114:E1345-E1354. [PMID: 28154134 DOI: 10.1073/pnas.1615105114] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
On pathological stress, Wnt signaling is reactivated and induces genes associated with cardiac remodeling and fibrosis. We have previously shown that a cell surface receptor Cdon (cell-adhesion associated, oncogene regulated) suppresses Wnt signaling to promote neuronal differentiation however its role in heart is unknown. Here, we demonstrate a critical role of Cdon in cardiac function and remodeling. Cdon is expressed and predominantly localized at intercalated disk in both mouse and human hearts. Cdon-deficient mice develop cardiac dysfunction including reduced ejection fraction and ECG abnormalities. Cdon-/- hearts exhibit increased fibrosis and up-regulation of genes associated with cardiac remodeling and fibrosis. Electrical remodeling was demonstrated by up-regulation and mislocalization of the gap junction protein, Connexin 43 (Cx43) in Cdon-/- hearts. In agreement with altered Cx43 expression, functional analysis both using Cdon-/- cardiomyocytes and shRNA-mediated knockdown in rat cardiomyocytes shows aberrant gap junction activities. Analysis of the underlying mechanism reveals that Cdon-/- hearts exhibit hyperactive Wnt signaling as evident by β-catenin accumulation and Axin2 up-regulation. On the other hand, the treatment of rat cardiomyocytes with a Wnt activator TWS119 reduces Cdon levels and aberrant Cx43 activities, similarly to Cdon-deficient cardiomyocytes, suggesting a negative feedback between Cdon and Wnt signaling. Finally, inhibition of Wnt/β-catenin signaling by XAV939, IWP2 or dickkopf (DKK)1 prevented Cdon depletion-induced up-regulation of collagen 1a and Cx43. Taken together, these results demonstrate that Cdon deficiency causes hyperactive Wnt signaling leading to aberrant intercellular coupling and cardiac fibrosis. Cdon exhibits great potential as a target for the treatment of cardiac fibrosis and cardiomyopathy.
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247
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Fujita T, Umemura M, Yokoyama U, Okumura S, Ishikawa Y. The role of Epac in the heart. Cell Mol Life Sci 2017; 74:591-606. [PMID: 27549789 PMCID: PMC11107744 DOI: 10.1007/s00018-016-2336-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 07/21/2016] [Accepted: 08/09/2016] [Indexed: 02/08/2023]
Abstract
As one of the most important second messengers, 3',5'-cyclic adenosine monophosphate (cAMP) mediates various extracellular signals including hormones and neurotransmitters, and induces appropriate responses in diverse types of cells. Since cAMP was formerly believed to transmit signals through only two direct target molecules, protein kinase A and the cyclic nucleotide-gated channel, the sensational discovery in 1998 of another novel direct effecter of cAMP [exchange proteins directly activated by cAMP (Epac)] attracted a great deal of scientific interest in cAMP signaling. Numerous studies on Epac have since disclosed its important functions in various tissues in the body. Recently, observations of genetically manipulated mice in various pathogenic models have begun to reveal the in vivo significance of previous in vitro or cellular-level findings. Here, we focused on the function of Epac in the heart. Accumulating evidence has revealed that both Epac1 and Epac2 play important roles in the structure and function of the heart under physiological and pathological conditions. Accordingly, developing the ability to regulate cAMP-mediated signaling through Epac may lead to remarkable new therapies for the treatment of cardiac diseases.
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Affiliation(s)
- Takayuki Fujita
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
| | - Masanari Umemura
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Utako Yokoyama
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
| | - Satoshi Okumura
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan
- Tsurumi University School of Dental Medicine, Yokohama, Japan
| | - Yoshihiro Ishikawa
- Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
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248
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Hu W, Xu T, Wu P, Pan D, Chen J, Chen J, Zhang B, Zhu H, Li D. Luteolin improves cardiac dysfunction in heart failure rats by regulating sarcoplasmic reticulum Ca 2+-ATPase 2a. Sci Rep 2017; 7:41017. [PMID: 28112209 PMCID: PMC5253630 DOI: 10.1038/srep41017] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 12/15/2016] [Indexed: 12/24/2022] Open
Abstract
We previously found that luteolin (Lut) appeared to improve the contractility of cardiomyocytes during ischemia/reperfusion in rats. The enhancement was associated with the alteration in sarcoplasmic reticulum Ca2+-ATPase 2a (SERCA2a). This finding prompted us to consider if the mechanism worked in heart failure (HF). We studied the regulation of SERCA2a by Lut in failing cardiomyocytes and intact heart of rats. Improvement of contractility and the mechanisms centered on SERCA2a were studied in isolated cardiomyocytes and intact heart. We found that Lut significantly improved contractility and Ca2+ transients, ameliorated expression, activity and stability of SERCA2a and upregulated expression of small ubiquitin-related modifier (SUMO) 1, which is a newfound SERCA2a regulator. Lut also increased phosphorylation of protein kinase B (Akt), phospholaban (PLB) and sumoylation of SERCA2a, specificity protein 1 (Sp1). Transcriptions of SUMO1 and SERCA2a were concurrently increased. Inhibition of posphatidylinositol 3 kinase/Akt (PI3K/Akt) pathway and SERCA2a activity both markedly abolished Lut-induced benefits in vitro and in vivo. Lut upregulated the expression ratio of Bcl-2/Bax, caspase-3/cleaved-Caspase3. Meanwhile, Lut ameliorated the myocardium fibrosis of HF. These discoveries provide an important potential therapeutic strategy that Lut targeted SERCA2a SUMOylation related to PI3K/Akt-mediated regulations on rescuing the dysfunction of HF.
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Affiliation(s)
- Wenjing Hu
- Institute of Cardiovascular Disease Research, Xuzhou Medical University, Xuzhou, Jiangsu, 221002, China
| | - Tongda Xu
- Department of Cardiology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, 221006, China
| | - Pei Wu
- Institute of Cardiovascular Disease Research, Xuzhou Medical University, Xuzhou, Jiangsu, 221002, China
| | - Defeng Pan
- Institute of Cardiovascular Disease Research, Xuzhou Medical University, Xuzhou, Jiangsu, 221002, China
| | - Junhong Chen
- Department of Cardiology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, 221006, China
| | - Jing Chen
- Department of Cardiology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, 221006, China
| | - Buchun Zhang
- Institute of Cardiovascular Disease Research, Xuzhou Medical University, Xuzhou, Jiangsu, 221002, China
| | - Hong Zhu
- Department of Cardiology, Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, 221006, China
| | - Dongye Li
- Institute of Cardiovascular Disease Research, Xuzhou Medical University, Xuzhou, Jiangsu, 221002, China
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Desplantez T. Cardiac Cx43, Cx40 and Cx45 co-assembling: involvement of connexins epitopes in formation of hemichannels and Gap junction channels. BMC Cell Biol 2017; 18:3. [PMID: 28124623 PMCID: PMC5267329 DOI: 10.1186/s12860-016-0118-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Background This review comes after the International Gap Junction Conference (IGJC 2015) and describes the current knowledge on the function of the specific motifs of connexins in the regulation of the formation of gap junction channels. Moreover the review is complemented by a summarized description of the distinct contribution of gap junction channels in the electrical coupling. Results Complementary biochemical and functional characterization on cell models and primary cells have improved our understanding on the oligomerization of connexins and the formation and the electrical properties of gap junction channels. Studies mostly focused cardiac connexins Cx43 and Cx40 expressed in myocytes, while Cx45 and Cx30.2 have been less investigated, for which main findings are reviewed to highlight their critical contribution in the formation of gap junction channels for ensuring the orchestrated electrical impulse propagation and coordination of atrial and ventricular contraction and heart function, whereas connexin dysfunction and remodeling are pro-arrhythmic factors. Common and specific motifs of residues identified in different domain of each type of connexin determine the connexin homo- and hetero-oligomerization and the channels formation, which leads to specific electrical properties. Conclusions These motifs and the resulting formation of gap junction channels are keys to ensure the tissue homeostasis and function in each connexin expression pattern in various tissues of multicellular organisms. Altogether, the findings to date have significantly improved our understanding on the function of the different connexin expression patterns in healthy and diseased tissues, and promise further investigations on the contribution in the different types of connexin.
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Affiliation(s)
- Thomas Desplantez
- IHU Liryc, Electrophysiology and Heart Modeling Institute, Fondation Bordeaux Université, Campus X. Arnozan, Avenue Haut Leveque, 33600, Pessac- Bordeaux, France. .,Univ. Bordeaux, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, F-33000, Bordeaux, France. .,INSERM, Centre de recherche Cardio-Thoracique de Bordeaux, U1045, F-33000, Bordeaux, France.
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Early remodeling of repolarizing K + currents in the αMHC 403/+ mouse model of familial hypertrophic cardiomyopathy. J Mol Cell Cardiol 2017; 103:93-101. [PMID: 28089740 DOI: 10.1016/j.yjmcc.2017.01.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 01/10/2017] [Accepted: 01/11/2017] [Indexed: 11/20/2022]
Abstract
Familial hypertrophic cardiomyopathy (HCM), linked to mutations in myosin, myosin-binding proteins and other sarcolemmal proteins, is associated with increased risk of life threatening ventricular arrhythmias, and a number of animal models have been developed to facilitate analysis of disease progression and mechanisms. In the experiments here, we use the αMHC403/+ mouse line in which one αMHC allele harbors a common HCM mutation (in βMHC, Arg403 Gln). Here, we demonstrate marked prolongation of QT intervals in young adult (10-12week) male αMHC403/+ mice, well in advance of the onset of measurable left ventricular hypertrophy. Electrophysiological recordings from myocytes isolated from the interventricular septum of these animals revealed significantly (P<0.001) lower peak repolarizing voltage-gated K+ (Kv) current (IK,peak) amplitudes, compared with cells isolated from wild type (WT) littermate controls. Analysis of Kv current waveforms revealed that the amplitudes of the inactivating components of the total outward Kv current, Ito,f, Ito,s and IK,slow, were significantly lower in αMHC403/+, compared with WT, septum cells, whereas Iss amplitudes were similar. The amplitudes/densities of IK,peak and IK,slow were also lower in αMHC403/+, compared with WT, LV wall and LV apex myocytes, whereas Ito,f was attenuated in αMHC403/+ LV wall, but not LV apex, cells. These regional differences in the remodeling of repolarizing Kv currents in the αMHC403/+ mice would be expected to increase the dispersion of ventricular repolarization and be proarrhythmic. Quantitative RT-PCR analysis revealed reductions in the expression of transcripts encoding several K+ channel subunits in the interventricular septum, LV free wall and LV apex of (10-12week) αMHC403/+ mice, although this transcriptional remodeling was not correlated with the observed decreases in K+ current amplitudes.
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