1
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Lee WS, Abel ED, Kim J. New Insights into IGF-1 Signaling in the Heart. Physiology (Bethesda) 2024; 39:0. [PMID: 38713091 DOI: 10.1152/physiol.00003.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 04/24/2024] [Accepted: 05/04/2024] [Indexed: 05/08/2024] Open
Abstract
Insulin-like growth factor-1 (IGF-1) signaling has multiple physiological roles in cellular growth, metabolism, and aging. Myocardial hypertrophy, cell death, senescence, fibrosis, and electrical remodeling are hallmarks of various heart diseases and contribute to the progression of heart failure. This review highlights the critical role of IGF-1 and its cognate receptor in cardiac hypertrophy, aging, and remodeling.
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Affiliation(s)
- Wang-Soo Lee
- Division of Cardiology, Department of Internal Medicine, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
| | - E Dale Abel
- Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, California, United States
| | - Jaetaek Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Chung-Ang University, Seoul, Republic of Korea
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2
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Chen B, Tan L, Wang Y, Yang L, Liu J, Chen D, Huang S, Mao F, Lian J. LOC102549726/miR-760-3p network is involved in the progression of ISO-induced pathological cardiomyocyte hypertrophy via endoplasmic reticulum stress. J Mol Histol 2023; 54:675-687. [PMID: 37899367 PMCID: PMC10635935 DOI: 10.1007/s10735-023-10166-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Accepted: 09/30/2023] [Indexed: 10/31/2023]
Abstract
Pathological cardiac hypertrophy (CH) is featured by myocyte enlargement and cardiac malfunction. Multiple signaling pathways have been implicated in diverse pathological and physiological processes in CH. However, the function of LOC102549726/miR-760-3p network in CH remains unclear. Here, we characterize the functional role of LOC102549726/miR-760-3p network in CH and delineate the underlying mechanism. The expression of LncRNA LOC102549726 and hypertrophic markers was significantly increased compared to the control, while the level of miR-760-3p was decreased. Next, we examined ER stress response in a hypertrophic cardiomyocyte model. The expression of ER stress markers was greatly enhanced after incubation with ISO. The hypertrophic reaction, ER stress response, and increased potassium and calcium ion channels were alleviated by genetic downregulation of LOC102549726. It has been demonstrated that LOC102549726 functions as a competitive endogenous RNA (ceRNA) of miR-760-3p. Overexpression of miR-760-3p decreased cell surface area and substantially mitigated ER stress response; protein levels of potassium and calcium channels were also significantly up-regulated compared to the NC control. In contrast, miR-760-3p inhibition increased cell size, aggravated CH and ER stress responses, and reduced ion channels. Collectively, in this study we demonstrated that the LOC102549726/miR-760-3p network was a crucial regulator of CH development. Ion channels mediate the ER stress response and may be a downstream sensor of the LOC102549726/miR-760-3p network. Therefore, these findings advance our understanding of pathological CH and provide new insights into therapeutic targets for cardiac remodeling.
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Affiliation(s)
- Bangsheng Chen
- Emergency Medical Center, Ningbo Yinzhou No. 2 Hospital, Ningbo, Zhejiang, 315192, China
| | - Lian Tan
- Intensive Care Unit, Ningbo Yinzhou No. 2 Hospital, Ningbo, Zhejiang, 315192, China
| | - Ying Wang
- Cadiovascular Department, Ningbo Medical Center LiHuiLi Hospital, Ningbo, Zhejiang, 315100, China
| | - Lei Yang
- Emergency Medical Center, Ningbo Yinzhou No. 2 Hospital, Ningbo, Zhejiang, 315192, China
| | - Jiequan Liu
- Emergency Medical Center, Ningbo Yinzhou No. 2 Hospital, Ningbo, Zhejiang, 315192, China
| | - Danqi Chen
- Intensive Care Unit, Ningbo Yinzhou No. 2 Hospital, Ningbo, Zhejiang, 315192, China
| | - Shuaishuai Huang
- Laboratory of Renal Carcinoma, Ningbo Yinzhou No. 2 Hospital, Ningbo, Zhejiang, 315192, China
| | - Feiyan Mao
- Department of General Surgery, HwaMei Hospital, University of Chinese Academy of Sciences, Ningbo, Zhejiang, 315100, China
| | - Jiangfang Lian
- Cadiovascular Department, Ningbo Medical Center LiHuiLi Hospital, Ningbo, Zhejiang, 315100, China.
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3
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Chen Y, Liu Q, Yang T, Shen L, Xu D. Soluble Epoxide Hydrolase Inhibitors Regulate Ischemic Arrhythmia by Targeting MicroRNA-1. Front Physiol 2021; 12:717119. [PMID: 34646152 PMCID: PMC8502875 DOI: 10.3389/fphys.2021.717119] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2021] [Accepted: 08/26/2021] [Indexed: 12/19/2022] Open
Abstract
Background: Soluble epoxide hydrolase inhibitors (sEHis) inhibit the degradation of epoxyeicosatrienoic acids (EETs) in cells, and EETs have antiarrhythmic effects. Our previous experiments confirmed that t-AUCB, a preparation of sEHis, inhibited ischemic arrhythmia by negatively regulating microRNA-1 (miR-1), but its specific mechanism remained unclear. Aim: This study aimed to examine the role of serum response factor (SRF) and the PI3K/Akt/GSK3β pathway in t-AUCB-mediated regulation of miR-1 and the interaction between them. Methods/Results: We used SRF small interfering RNA (siSRF), SRF small hairpin (shSRF) RNA sequence adenovirus, PI3K/Akt/GSK3β pathway inhibitors, t-AUCB, and 14,15-EEZE (a preparation of EETs antagonists) to treat mouse cardiomyocytes overexpressing miR-1 and mice with myocardial infarction (MI). We found that silencing SRF attenuated the effects on miR-1 and its target genes KCNJ2 and GJA1 in the presence of t-AUCB, and inhibition of the PI3K/Akt/GSK3β pathway antagonized the effects of t-AUCB on miR-1, KCNJ2, and GJA1, which were associated with PI3Kα, Akt, and Gsk3β but not PI3Kβ or PI3Kγ. Moreover, the PI3K/Akt/GSK3β pathway was involved in the regulation of SRF by t-AUCB, and silencing SRF inhibited the t-AUCB-induced increases in Akt and Gsk3β phosphorylation. Conclusions: Both the SRF and the PI3K/Akt/GSK3β pathway are involved in the t-AUCB-mediated regulation of miR-1, and these factors interact with each other.
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Affiliation(s)
- Yanying Chen
- Department of Internal Cardiovascular Medicine, Second Xiangya Hospital, Central South University, Changsha, China
| | - Qiong Liu
- Department of Internal Cardiovascular Medicine, Second Xiangya Hospital, Central South University, Changsha, China
| | - Tian Yang
- Department of Internal Cardiovascular Medicine, Second Xiangya Hospital, Central South University, Changsha, China
| | - Li Shen
- Department of Internal Cardiovascular Medicine, Second Xiangya Hospital, Central South University, Changsha, China
| | - Danyan Xu
- Department of Internal Cardiovascular Medicine, Second Xiangya Hospital, Central South University, Changsha, China
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4
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Ezeani M, Prabhu S. Pathophysiology and therapeutic relevance of PI3K(p110α) protein in atrial fibrillation: A non-interventional molecular therapy strategy. Pharmacol Res 2021; 165:105415. [PMID: 33412279 DOI: 10.1016/j.phrs.2020.105415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 12/04/2020] [Accepted: 12/23/2020] [Indexed: 10/22/2022]
Abstract
Genetically modified animal studies have revealed specific expression patterns and unequivocal roles of class I PI3K isoenzymes. PI3K(p110α), a catalytic subunit of class I PI3Ks is ubiquitously expressed and is well characterised in the cardiovascular system. Given that genetic inhibition of PI3K(p110α) causes lethal phenotype embryonically, the catalytic subunit is critically important in housekeeping and biological processes. A growing number of studies underpin crucial roles of PI3K(p110α) in cell survival, proliferation, hypertrophy and arrhythmogenesis. While the studies provide great insights, the precise mechanisms involved in PI3K(p110α) hypofunction and atrial fibrillation (AF) are not fully known. AF is a well recognised clinical problem with significant management limitations. In this translational review, we attempted a narration of PI3K(p110α) hypofunction in the molecular basis of AF pathophysiology. We sought to cautiously highlight the relevance of this molecule in the therapeutic approaches for AF management per se (i.e without conditions associate with cell proliferation, like cancer), and in mitigating effects of clinical risk factors in atrial substrate formation leading to AF progression. We also considered PI3K(p110α) in AF gene association, with the aim of identifying mechanistic links between the ever increasingly well-defined genetic loci (regions and genes) and AF. Such mechanisms will aid in identifying new drug targets for arrhythmogenic substrate and AF.
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Affiliation(s)
- Martin Ezeani
- NanoBiotechnology Laboratory, Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Victoria, 3004, Australia.
| | - Sandeep Prabhu
- The Alfred, and Baker Heart and Diabetes Institute, Melbourne, Australia; University of Melbourne, Melbourne, Australia
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5
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Xiang K, Qin Z, Zhang H, Liu X. Energy Metabolism in Exercise-Induced Physiologic Cardiac Hypertrophy. Front Pharmacol 2020; 11:1133. [PMID: 32848751 PMCID: PMC7403221 DOI: 10.3389/fphar.2020.01133] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 07/13/2020] [Indexed: 12/17/2022] Open
Abstract
Physiologic hypertrophy of the heart preserves or enhances systolic function without interstitial fibrosis or cell death. As a unique form of physiological stress, regular exercise training can trigger the adaptation of cardiac muscle to cause physiological hypertrophy, partly due to its ability to improve cardiac metabolism. In heart failure (HF), cardiac dysfunction is closely associated with early initiation of maladaptive metabolic remodeling. A large amount of clinical and experimental evidence shows that metabolic homeostasis plays an important role in exercise training, which is conducive to the treatment and recovery of cardiovascular diseases. Potential mechanistic targets for modulation of cardiac metabolism have become a hot topic at present. Thus, exploring the energy metabolism mechanism in exercise-induced physiologic cardiac hypertrophy may produce new therapeutic targets, which will be helpful to design novel effective strategies. In this review, we summarize the changes of myocardial metabolism (fatty acid metabolism, carbohydrate metabolism, and mitochondrial adaptation), metabolically-related signaling molecules, and probable regulatory mechanism of energy metabolism during exercise-induced physiological cardiac hypertrophy.
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Affiliation(s)
- Kefa Xiang
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
| | - Zhen Qin
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
| | - Huimin Zhang
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
| | - Xia Liu
- Department of Clinical Pharmacy, School of Pharmacy, Second Military Medical University, Shanghai, China
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6
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Zhabyeyev P, Chen X, Vanhaesebroeck B, Oudit GY. PI3Kα in cardioprotection: Cytoskeleton, late Na + current, and mechanism of arrhythmias. Channels (Austin) 2020; 13:520-532. [PMID: 31790629 PMCID: PMC6930018 DOI: 10.1080/19336950.2019.1697127] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
PI 3-kinase α (PI3Kα) is a lipid kinase that converts phosphatidylinositol-4,5-bisphosphate (PIP2) to phosphatidylinositol-3,4,5-triphosphate (PIP3). PI3Kα regulates a variety of cellular processes such as nutrient sensing, cell cycle, migration, and others. Heightened activity of PI3Kα in many types of cancer made it a prime oncology drug target, but also raises concerns of possible adverse effects on the heart. Indeed, recent advances in preclinical models demonstrate an important role of PI3Kα in the control of cytoskeletal integrity, Na+ channel activity, cardioprotection, and prevention of arrhythmias.
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Affiliation(s)
- Pavel Zhabyeyev
- Department of Medicine, University of Alberta, Edmonton, Canada.,Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
| | - Xueyi Chen
- Department of Medicine, University of Alberta, Edmonton, Canada.,Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
| | | | - Gavin Y Oudit
- Department of Medicine, University of Alberta, Edmonton, Canada.,Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
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7
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Metabolic regulation of Kv channels and cardiac repolarization by Kvβ2 subunits. J Mol Cell Cardiol 2019; 137:93-106. [PMID: 31639389 DOI: 10.1016/j.yjmcc.2019.09.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 09/24/2019] [Accepted: 09/28/2019] [Indexed: 11/21/2022]
Abstract
Voltage-gated potassium (Kv) channels control myocardial repolarization. Pore-forming Kvα proteins associate with intracellular Kvβ subunits, which bind pyridine nucleotides with high affinity and differentially regulate channel trafficking, plasmalemmal localization and gating properties. Nevertheless, it is unclear how Kvβ subunits regulate myocardial K+ currents and repolarization. Here, we tested the hypothesis that Kvβ2 subunits regulate the expression of myocardial Kv channels and confer redox sensitivity to Kv current and cardiac repolarization. Co-immunoprecipitation and in situ proximity ligation showed that in cardiac myocytes, Kvβ2 interacts with Kv1.4, Kv1.5, Kv4.2, and Kv4.3. Cardiac myocytes from mice lacking Kcnab2 (Kvβ2-/-) had smaller cross sectional areas, reduced sarcolemmal abundance of Kvα binding partners, reduced Ito, IK,slow1, and IK,slow2 densities, and prolonged action potential duration compared with myocytes from wild type mice. These differences in Kvβ2-/- mice were associated with greater P wave duration and QT interval in electrocardiograms, and lower ejection fraction, fractional shortening, and left ventricular mass in echocardiographic and morphological assessments. Direct intracellular dialysis with a high NAD(P)H:NAD(P)+ accelerated Kv inactivation in wild type, but not Kvβ2-/- myocytes. Furthermore, elevated extracellular levels of lactate increased [NADH]i and prolonged action potential duration in wild type cardiac myocytes and perfused wild type, but not Kvβ2-/-, hearts. Taken together, these results suggest that Kvβ2 regulates myocardial electrical activity by supporting the functional expression of proteins that generate Ito and IK,slow, and imparting redox and metabolic sensitivity to Kv channels, thereby coupling cardiac repolarization to myocyte metabolism.
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8
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Zhabyeyev P, McLean B, Chen X, Vanhaesebroeck B, Oudit GY. Inhibition of PI3Kinase-α is pro-arrhythmic and associated with enhanced late Na + current, contractility, and Ca 2+ release in murine hearts. J Mol Cell Cardiol 2019; 132:98-109. [PMID: 31095940 DOI: 10.1016/j.yjmcc.2019.05.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 04/11/2019] [Accepted: 05/09/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND Phosphoinositide 3-kinase α (PI3Kα) is a proto-oncogene with high activity in the heart. BYL719 (BYL) is a PI3Kα-selective small molecule inhibitor and a prospective drug for advanced solid tumors. We investigated whether acute pharmacological inhibition of PI3Kα has pro-arrhythmic effects. METHODS & RESULTS In isolated wild-type (WT) cardiomyocytes, pharmacological inhibition of PI3Kα (BYL719) increased contractility by 28%, Ca2+ release by 20%, and prolonged action potential (AP) repolarization by 10-15%. These effects of BYL719 were abolished by inhibition of reverse-mode Na+/Ca2+ exchanger (NCX) (KB-R7943) or by inhibition of late Na+ current (INa-L) (ranolazine). BYL719 had no effect on PI3Kα-deficient cardiomyocytes, suggesting BYL719 effects were PI3Kα-dependent and mediated via NCX and INa-L. INa-L was suppressed by activation of PI3Kα, application of exogenous intracellular PIP3, or ranolazine. Investigation of AP and Ca2+ release in whole heart preparations using epicardial optical mapping showed that inhibition of PI3Kα similarly led to prolongation of AP and enhancement of Ca2+ release. In hearts of PI3Kα-deficient mice, β-adrenergic stimulation in the presence of high Ca2+ concentrations and 12-Hz burst pacing led to delayed afterdepolarizations and ventricular fibrillation. In vivo, administration of BYL719 prolonged QT interval [QTcF (Fridericia) increased by 15%] in WT, but not in PI3Kα-deficient mice. CONCLUSIONS Pharmacological inhibition of PI3Kα is arrhythmogenic due to activation of INa-L leading to increased sarcoplasmic reticulum Ca2+ load and prolonged QT interval. Therefore, monitoring of cardiac electrical activity in patients receiving PI3K inhibitors may provide further insights into the arrhythmogenic potential of PI3Ka inhibition.
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Affiliation(s)
- Pavel Zhabyeyev
- Department of Medicine, University of Alberta, Edmonton, Canada; Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
| | - Brent McLean
- Department of Medicine, University of Alberta, Edmonton, Canada; Department of Physiology, University of Alberta, Edmonton, Canada; Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
| | - Xueyi Chen
- Department of Medicine, University of Alberta, Edmonton, Canada; Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada
| | | | - Gavin Y Oudit
- Department of Medicine, University of Alberta, Edmonton, Canada; Mazankowski Alberta Heart Institute, University of Alberta, Edmonton, Canada.
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9
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Li C, Zou R, Zhang H, Wang Y, Qiu B, Qiu S, Wang W, Xu Y. Upregulation of phosphoinositide 3-kinase prevents sunitinib-induced cardiotoxicity in vitro and in vivo. Arch Toxicol 2019; 93:1697-1712. [DOI: 10.1007/s00204-019-02448-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 04/09/2019] [Indexed: 12/20/2022]
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10
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Bernardo BC, Ooi JYY, Weeks KL, Patterson NL, McMullen JR. Understanding Key Mechanisms of Exercise-Induced Cardiac Protection to Mitigate Disease: Current Knowledge and Emerging Concepts. Physiol Rev 2018; 98:419-475. [PMID: 29351515 DOI: 10.1152/physrev.00043.2016] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The benefits of exercise on the heart are well recognized, and clinical studies have demonstrated that exercise is an intervention that can improve cardiac function in heart failure patients. This has led to significant research into understanding the key mechanisms responsible for exercise-induced cardiac protection. Here, we summarize molecular mechanisms that regulate exercise-induced cardiac myocyte growth and proliferation. We discuss in detail the effects of exercise on other cardiac cells, organelles, and systems that have received less or little attention and require further investigation. This includes cardiac excitation and contraction, mitochondrial adaptations, cellular stress responses to promote survival (heat shock response, ubiquitin-proteasome system, autophagy-lysosomal system, endoplasmic reticulum unfolded protein response, DNA damage response), extracellular matrix, inflammatory response, and organ-to-organ crosstalk. We summarize therapeutic strategies targeting known regulators of exercise-induced protection and the challenges translating findings from bench to bedside. We conclude that technological advancements that allow for in-depth profiling of the genome, transcriptome, proteome and metabolome, combined with animal and human studies, provide new opportunities for comprehensively defining the signaling and regulatory aspects of cell/organelle functions that underpin the protective properties of exercise. This is likely to lead to the identification of novel biomarkers and therapeutic targets for heart disease.
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Affiliation(s)
- Bianca C Bernardo
- Baker Heart and Diabetes Institute , Melbourne , Australia ; Department of Paediatrics, University of Melbourne , Victoria , Australia ; Department of Diabetes, Central Clinical School, Monash University , Victoria , Australia ; Department of Medicine, Central Clinical School, Monash University , Victoria , Australia ; and Department of Physiology, School of Biomedical Sciences , Victoria , Australia
| | - Jenny Y Y Ooi
- Baker Heart and Diabetes Institute , Melbourne , Australia ; Department of Paediatrics, University of Melbourne , Victoria , Australia ; Department of Diabetes, Central Clinical School, Monash University , Victoria , Australia ; Department of Medicine, Central Clinical School, Monash University , Victoria , Australia ; and Department of Physiology, School of Biomedical Sciences , Victoria , Australia
| | - Kate L Weeks
- Baker Heart and Diabetes Institute , Melbourne , Australia ; Department of Paediatrics, University of Melbourne , Victoria , Australia ; Department of Diabetes, Central Clinical School, Monash University , Victoria , Australia ; Department of Medicine, Central Clinical School, Monash University , Victoria , Australia ; and Department of Physiology, School of Biomedical Sciences , Victoria , Australia
| | - Natalie L Patterson
- Baker Heart and Diabetes Institute , Melbourne , Australia ; Department of Paediatrics, University of Melbourne , Victoria , Australia ; Department of Diabetes, Central Clinical School, Monash University , Victoria , Australia ; Department of Medicine, Central Clinical School, Monash University , Victoria , Australia ; and Department of Physiology, School of Biomedical Sciences , Victoria , Australia
| | - Julie R McMullen
- Baker Heart and Diabetes Institute , Melbourne , Australia ; Department of Paediatrics, University of Melbourne , Victoria , Australia ; Department of Diabetes, Central Clinical School, Monash University , Victoria , Australia ; Department of Medicine, Central Clinical School, Monash University , Victoria , Australia ; and Department of Physiology, School of Biomedical Sciences , Victoria , Australia
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11
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Nystoriak MA, Bhatnagar A. Cardiovascular Effects and Benefits of Exercise. Front Cardiovasc Med 2018; 5:135. [PMID: 30324108 PMCID: PMC6172294 DOI: 10.3389/fcvm.2018.00135] [Citation(s) in RCA: 318] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 09/07/2018] [Indexed: 12/19/2022] Open
Abstract
It is widely accepted that regular physical activity is beneficial for cardiovascular health. Frequent exercise is robustly associated with a decrease in cardiovascular mortality as well as the risk of developing cardiovascular disease. Physically active individuals have lower blood pressure, higher insulin sensitivity, and a more favorable plasma lipoprotein profile. Animal models of exercise show that repeated physical activity suppresses atherogenesis and increases the availability of vasodilatory mediators such as nitric oxide. Exercise has also been found to have beneficial effects on the heart. Acutely, exercise increases cardiac output and blood pressure, but individuals adapted to exercise show lower resting heart rate and cardiac hypertrophy. Both cardiac and vascular changes have been linked to a variety of changes in tissue metabolism and signaling, although our understanding of the contribution of the underlying mechanisms remains incomplete. Even though moderate levels of exercise have been found to be consistently associated with a reduction in cardiovascular disease risk, there is evidence to suggest that continuously high levels of exercise (e.g., marathon running) could have detrimental effects on cardiovascular health. Nevertheless, a specific dose response relationship between the extent and duration of exercise and the reduction in cardiovascular disease risk and mortality remains unclear. Further studies are needed to identify the mechanisms that impart cardiovascular benefits of exercise in order to develop more effective exercise regimens, test the interaction of exercise with diet, and develop pharmacological interventions for those unwilling or unable to exercise.
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Affiliation(s)
- Matthew A Nystoriak
- Division of Cardiovascular Medicine, Department of Medicine, Diabetes and Obesity Center, Institute of Molecular Cardiology, University of Louisville, Louisville, KY, United States
| | - Aruni Bhatnagar
- Division of Cardiovascular Medicine, Department of Medicine, Diabetes and Obesity Center, Institute of Molecular Cardiology, University of Louisville, Louisville, KY, United States
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12
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Abstract
BACKGROUND Gastroparesis is characterized by abnormal gastric motility and delayed emptying with symptoms of early satiety, postprandial fullness, bloating, nausea, vomiting and abdominal pain. Pharmacological discovery has been lagging because potential drugs often are associated with abnormalities of electrical conduction of the myocardium due to interaction with cardiac ion channels leading to limited pharmaceutical options for development of new drugs. OBJECTIVE Addresses the safety of drugs for gastroparesis in terms of cardiotoxicity related to the clinical use of prokinetics and antiemetics. METHODS Survey of QT drugs List and review of current literature. RESULTS Many prokinetic drugs are associated with cardiac adverse events and manifest as prolongation of ventricular repolarization, i.e., QT-interval prolongation of the electrocardiogram. This disturbance may develop into a potentially fatal polymorphic ventricular tachyarrhythmia; Torsade de Pointes. Co-administration of prokinetics with other drugs affecting the repolarization process, pharmacokinetic interactions leading to increased blood levels, or the presence of clinical risk factors could further increase the risk for cardiac arrhythmias. CONCLUSIONS It is important that clinicians managing gastroparesis are aware of the arrhythmogenic potential of drugs used clinically and risk factors that contribute to QT prolongation to safeguard patients at risk for drug-induced cardiac arrhythmia.
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Affiliation(s)
- Per M Hellström
- a Department of Medical Sciences, Faculty of Medicine , Uppsala University , Uppsala , Sweden
| | - Ahmad Al-Saffar
- a Department of Medical Sciences, Faculty of Medicine , Uppsala University , Uppsala , Sweden
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13
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Influence of type of sport on cardiac repolarization assessed by electrocardiographic T-wave morphology combination score. J Electrocardiol 2018; 51:296-302. [DOI: 10.1016/j.jelectrocard.2017.09.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Indexed: 11/21/2022]
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14
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Burgos JI, Yeves AM, Barrena JP, Portiansky EL, Vila-Petroff MG, Ennis IL. Nitric oxide and CaMKII: Critical steps in the cardiac contractile response To IGF-1 and swim training. J Mol Cell Cardiol 2017; 112:16-26. [DOI: 10.1016/j.yjmcc.2017.08.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 08/23/2017] [Accepted: 08/24/2017] [Indexed: 10/18/2022]
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15
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Jeevaratnam K, Chadda KR, Huang CLH, Camm AJ. Cardiac Potassium Channels: Physiological Insights for Targeted Therapy. J Cardiovasc Pharmacol Ther 2017; 23:119-129. [PMID: 28946759 PMCID: PMC5808825 DOI: 10.1177/1074248417729880] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The development of novel drugs specifically directed at the ion channels underlying particular features of cardiac action potential (AP) initiation, recovery, and refractoriness would contribute to an optimized approach to antiarrhythmic therapy that minimizes potential cardiac and extracardiac toxicity. Of these, K+ channels contribute numerous and diverse currents with specific actions on different phases in the time course of AP repolarization. These features and their site-specific distribution make particular K+ channel types attractive therapeutic targets for the development of pharmacological agents attempting antiarrhythmic therapy in conditions such as atrial fibrillation. However, progress in the development of such temporally and spatially selective antiarrhythmic drugs against particular ion channels has been relatively limited, particularly in view of our incomplete understanding of the complex physiological roles and interactions of the various ionic currents. This review summarizes the physiological properties of the main cardiac potassium channels and the way in which they modulate cardiac electrical activity and then critiques a number of available potential antiarrhythmic drugs directed at them.
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Affiliation(s)
- Kamalan Jeevaratnam
- 1 Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,2 School of Medicine, Perdana University-Royal College of Surgeons Ireland, Serdang, Selangor Darul Ehsan, Malaysia
| | - Karan R Chadda
- 1 Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom.,3 Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Christopher L-H Huang
- 3 Physiological Laboratory, University of Cambridge, Cambridge, United Kingdom.,4 Division of Cardiovascular Biology, Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - A John Camm
- 5 Cardiac Clinical Academic Group, St George's Hospital Medical School, University of London, Cranmer Terrace, London, United Kingdom
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16
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Chen X, Qin M, Jiang W, Zhang Y, Liu X. Electrophysiological characteristics of pressure overload-induced cardiac hypertrophy and its influence on ventricular arrhythmias. PLoS One 2017; 12:e0183671. [PMID: 28863155 PMCID: PMC5580922 DOI: 10.1371/journal.pone.0183671] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 08/03/2017] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE To explore the cardiac electrophysiological characteristics of cardiac hypertrophy and its influence on the occurrence of ventricular tachyarrhythmias. METHODS Adult C57BL6 mice were randomly divided into a surgery group and a control group. Thoracic aortic constriction was performed on mice in the surgery group, and cardiac anatomical and ultrasonic evaluations were performed to confirm the success of the cardiac hypertrophy model 4 weeks after the operation. Using the Langendorff method of isolated heart perfusion, monophasic action potentials (MAPs) and the effective refractory period (ERP) at different parts of the heart (including the epi- and endo-myocardium of the left and right ventricles) were measured, and the induction rate of ventricular tachyarrhythmias was observed under programmed electrical stimulus (PES) and burst stimulus. Whole-cell patch-clamp was used to obtain the I-V characteristics of voltage-gated potassium channels in cardiomyocytes of different parts of the heart (including the epi- and endo-myocardium of the left and right ventricles) as well as the channels' properties of steady-state inactivation and recovery from inactivation. RESULTS The ratio of heart weight to body weight and the ratio of left ventricular weight to body weight in the surgery group were significantly higher than those in the control group (P < 0.05). Ultrasonic evaluation revealed that both interventricular septal diameter (IVSD) and left ventricle posterior wall diameter (LVPWD) in the surgery group were significantly larger than those in the control group (P < 0.05). Under PES and burst stimuli, the induction rates of arrhythmias in the surgery group significantly increased, reaching 41.2% and 23.5%, respectively. Both the QT interval and action potential duration (APD) in the surgery group were significantly longer than in the control group (P<0.01), and the changes showed obvious spatial heterogeneity. Whole-cell patch-clamp recordings demonstrated that the surgery group had significantly lower potassium current densities (IPeak, Ito, IKur, Iss, and IK1) at different parts of the heart than the control group (P < 0.01), and there were significant differences in the half-inactivation voltage (V1/2) and the inactivation-recovery time constant (τ) of Ito and IKur at different parts of the heart (P < 0.01) between the surgery group and the control group. In addition, the surgery group had significantly lower densities of IPeak, Ito, and IKur in cells of the endo-myocardium (P < 0.05), and the changes showed obvious spatial heterogeneity. CONCLUSION Changes in the current density and function of potassium channels contributed to irregular repolarization in cardiac hypertrophy, and the spatially heterogeneous changes of the channels may increase the occurrence of ventricular arrhythmias that accompany cardiac hypertrophy.
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Affiliation(s)
- Xiaowei Chen
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Mu Qin
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
- * E-mail: (XL); (MQ)
| | - Weifeng Jiang
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Yu Zhang
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Xu Liu
- Department of Cardiology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
- * E-mail: (XL); (MQ)
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17
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Tereshchenko LG, Soliman EZ, Davis BR, Oparil S. Risk stratification of sudden cardiac death in hypertension. J Electrocardiol 2017; 50:798-801. [PMID: 28916176 DOI: 10.1016/j.jelectrocard.2017.08.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Indexed: 12/28/2022]
Abstract
In the United States, up to 450,000 people per year die suddenly; an average of 1 sudden death every 70s. Strategies for preventing sudden cardiac death are urgently needed. Systemic arterial hypertension is a major risk factor for sudden cardiac death and the increasing burden of hypertension is a worldwide problem. The lifetime risk of sudden cardiac death at 30years of age is higher by 30% in individuals with hypertension. Each 20/10mmHg increase in systolic/diastolic blood pressure, is associated with a 20% additional increase in sudden cardiac death risk. Theoretically, antihypertensive treatment should be an effective strategy for sudden cardiac death prevention. However, a recent meta-analysis of 15 randomized controlled trials showed that antihypertensive treatment does not reduce the incidence of sudden cardiac death. This manuscript reviews ECG predictors of sudden cardiac death and the importance of risk stratification for appropriate management of hypertension.
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Affiliation(s)
- Larisa G Tereshchenko
- The Knight Cardiovascular Institute, Oregon Health & Science University, Portland, OR, United States.
| | - Elsayed Z Soliman
- Epidemiological Cardiology Research Center (EPICARE), Division of Public Health Sciences, Department of Medicine, Cardiology Section, Wake Forest School of Medicine, Winston Salem, NC, United States
| | - Barry R Davis
- University of Texas School of Public Health, Houston, TX, United States
| | - Suzanne Oparil
- University of Alabama at Birmingham, Department of Medicine, School of Medicine, Birmingham, AL, United States
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18
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Toib A, Zhang C, Borghetti G, Zhang X, Wallner M, Yang Y, Troupes CD, Kubo H, Sharp TE, Feldsott E, Berretta RM, Zalavadia N, Trappanese DM, Harper S, Gross P, Chen X, Mohsin S, Houser SR. Remodeling of repolarization and arrhythmia susceptibility in a myosin-binding protein C knockout mouse model. Am J Physiol Heart Circ Physiol 2017. [PMID: 28646025 DOI: 10.1152/ajpheart.00167.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Hypertrophic cardiomyopathy (HCM) is one of the most common genetic cardiac diseases and among the leading causes of sudden cardiac death (SCD) in the young. The cellular mechanisms leading to SCD in HCM are not well known. Prolongation of the action potential (AP) duration (APD) is a common feature predisposing hypertrophied hearts to SCD. Previous studies have explored the roles of inward Na+ and Ca2+ in the development of HCM, but the role of repolarizing K+ currents has not been defined. The objective of this study was to characterize the arrhythmogenic phenotype and cellular electrophysiological properties of mice with HCM, induced by myosin-binding protein C (MyBPC) knockout (KO), and to test the hypothesis that remodeling of repolarizing K+ currents causes APD prolongation in MyBPC KO myocytes. We demonstrated that MyBPC KO mice developed severe hypertrophy and cardiac dysfunction compared with wild-type (WT) control mice. Telemetric electrocardiographic recordings of awake mice revealed prolongation of the corrected QT interval in the KO compared with WT control mice, with overt ventricular arrhythmias. Whole cell current- and voltage-clamp experiments comparing KO with WT mice demonstrated ventricular myocyte hypertrophy, AP prolongation, and decreased repolarizing K+ currents. Quantitative RT-PCR analysis revealed decreased mRNA levels of several key K+ channel subunits. In conclusion, decrease in repolarizing K+ currents in MyBPC KO ventricular myocytes contributes to AP and corrected QT interval prolongation and could account for the arrhythmia susceptibility.NEW & NOTEWORTHY Ventricular myocytes isolated from the myosin-binding protein C knockout hypertrophic cardiomyopathy mouse model demonstrate decreased repolarizing K+ currents and action potential and QT interval prolongation, linking cellular repolarization abnormalities with arrhythmia susceptibility and the risk for sudden cardiac death in hypertrophic cardiomyopathy.
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Affiliation(s)
- Amir Toib
- Section of Pediatric Cardiology, St. Christopher's Hospital for Children and Department of Pediatrics, Drexel University College of Medicine, Philadelphia, Pennsylvania; and.,Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Chen Zhang
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Giulia Borghetti
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Xiaoxiao Zhang
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Markus Wallner
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Yijun Yang
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Constantine D Troupes
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Hajime Kubo
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Thomas E Sharp
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Eric Feldsott
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Remus M Berretta
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Neil Zalavadia
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Danielle M Trappanese
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Shavonn Harper
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Polina Gross
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Xiongwen Chen
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Sadia Mohsin
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
| | - Steven R Houser
- Cardiovascular Research Center and Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania
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19
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Krzesiak A, Delpech N, Sebille S, Cognard C, Chatelier A. Structural, Contractile and Electrophysiological Adaptations of Cardiomyocytes to Chronic Exercise. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 999:75-90. [PMID: 29022258 DOI: 10.1007/978-981-10-4307-9_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Cardiac beneficial effects of chronic exercise is well admitted. These effects mainly studied at the organ and organism integrated levels find their origin in cardiomyocyte adaptation. This chapter try to highlight the main trends of the data related to the different parameters subject to such adaptations. This is addressed through cardiomyocytes size and structure, calcium and contractile properties, and finally electrophysiological alterations induced by training as they transpire from the literature. Despite the clarifications needed to decipher healthy cardiomyocyte remodeling, this overview clearly show that cardiac cell plasticity ensure the cardiac adaptation to exercise training and offers an interesting mean of action to counteract physiological disturbances induced by cardiac pathologies.
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Affiliation(s)
- A Krzesiak
- Equipe Transferts Ioniques et Rythmicité Cardiaque (TIRC), Lab. Signalisation et Transports Ioniques Membranaires (STIM), ERL CNRS/Université de Poitiers n°7368, Faculté des Sciences Fondamentales et Appliquées, Pôle Biologie Santé Bât B36/B37, 1 rue Georges Bonnet TSA 51106, 86073, Poitiers Cedex 9, France.,Laboratoire Mobilité, Vieillissement & Exercice (MOVE) - EA 6314, Faculté des Sciences du Sport Bât C6, 8, allée Jean Monnet, TSA 31113, 86073, Poitiers Cedex 9, France
| | - N Delpech
- Laboratoire Mobilité, Vieillissement & Exercice (MOVE) - EA 6314, Faculté des Sciences du Sport Bât C6, 8, allée Jean Monnet, TSA 31113, 86073, Poitiers Cedex 9, France
| | - S Sebille
- Equipe Transferts Ioniques et Rythmicité Cardiaque (TIRC), Lab. Signalisation et Transports Ioniques Membranaires (STIM), ERL CNRS/Université de Poitiers n°7368, Faculté des Sciences Fondamentales et Appliquées, Pôle Biologie Santé Bât B36/B37, 1 rue Georges Bonnet TSA 51106, 86073, Poitiers Cedex 9, France
| | - C Cognard
- Equipe Transferts Ioniques et Rythmicité Cardiaque (TIRC), Lab. Signalisation et Transports Ioniques Membranaires (STIM), ERL CNRS/Université de Poitiers n°7368, Faculté des Sciences Fondamentales et Appliquées, Pôle Biologie Santé Bât B36/B37, 1 rue Georges Bonnet TSA 51106, 86073, Poitiers Cedex 9, France
| | - A Chatelier
- Equipe Transferts Ioniques et Rythmicité Cardiaque (TIRC), Lab. Signalisation et Transports Ioniques Membranaires (STIM), ERL CNRS/Université de Poitiers n°7368, Faculté des Sciences Fondamentales et Appliquées, Pôle Biologie Santé Bât B36/B37, 1 rue Georges Bonnet TSA 51106, 86073, Poitiers Cedex 9, France.
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20
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Grandi E, Sanguinetti MC, Bartos DC, Bers DM, Chen-Izu Y, Chiamvimonvat N, Colecraft HM, Delisle BP, Heijman J, Navedo MF, Noskov S, Proenza C, Vandenberg JI, Yarov-Yarovoy V. Potassium channels in the heart: structure, function and regulation. J Physiol 2016; 595:2209-2228. [PMID: 27861921 DOI: 10.1113/jp272864] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Accepted: 07/18/2016] [Indexed: 12/22/2022] Open
Abstract
This paper is the outcome of the fourth UC Davis Systems Approach to Understanding Cardiac Excitation-Contraction Coupling and Arrhythmias Symposium, a biannual event that aims to bring together leading experts in subfields of cardiovascular biomedicine to focus on topics of importance to the field. The theme of the 2016 symposium was 'K+ Channels and Regulation'. Experts in the field contributed their experimental and mathematical modelling perspectives and discussed emerging questions, controversies and challenges on the topic of cardiac K+ channels. This paper summarizes the topics of formal presentations and informal discussions from the symposium on the structural basis of voltage-gated K+ channel function, as well as the mechanisms involved in regulation of K+ channel gating, expression and membrane localization. Given the critical role for K+ channels in determining the rate of cardiac repolarization, it is hardly surprising that essentially every aspect of K+ channel function is exquisitely regulated in cardiac myocytes. This regulation is complex and highly interrelated to other aspects of myocardial function. K+ channel regulatory mechanisms alter, and are altered by, physiological challenges, pathophysiological conditions, and pharmacological agents. An accompanying paper focuses on the integrative role of K+ channels in cardiac electrophysiology, i.e. how K+ currents shape the cardiac action potential, and how their dysfunction can lead to arrhythmias, and discusses K+ channel-based therapeutics. A fundamental understanding of K+ channel regulatory mechanisms and disease processes is fundamental to reveal new targets for human therapy.
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Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Davis, CA, 95616, USA
| | - Michael C Sanguinetti
- Department of Internal Medicine, University of Utah, Nora Eccles Harrison Cardiovascular Research and Training Institute, Salt Lake City, UT, 84112, USA
| | - Daniel C Bartos
- Department of Pharmacology, University of California, Davis, Davis, CA, 95616, USA
| | - Donald M Bers
- Department of Pharmacology, University of California, Davis, Davis, CA, 95616, USA
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, Davis, CA, 95616, USA.,Department of Internal Medicine, Division of Cardiology, University of California, Davis, CA, 95616, USA
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, Division of Cardiology, University of California, Davis, CA, 95616, USA
| | - Henry M Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, 10032, USA
| | - Brian P Delisle
- Department of Physiology, University of Kentucky, Lexington, KY, 40536, USA
| | - Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Manuel F Navedo
- Department of Pharmacology, University of California, Davis, Davis, CA, 95616, USA
| | - Sergei Noskov
- Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, AB, T2N 1N4, Canada
| | - Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado - Anschutz Medical Campus, Denver, CO, 80045, USA
| | - Jamie I Vandenberg
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW, 2010, Australia
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, University of California, Davis, CA, 95616, USA
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21
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Ford NC, Baccei ML. Inward-rectifying K + (K ir2) leak conductance dampens the excitability of lamina I projection neurons in the neonatal rat. Neuroscience 2016; 339:502-510. [PMID: 27751963 DOI: 10.1016/j.neuroscience.2016.10.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 09/20/2016] [Accepted: 10/07/2016] [Indexed: 01/03/2023]
Abstract
Spinal lamina I projection neurons serve as a major conduit by which noxious stimuli detected in the periphery are transmitted to nociceptive circuits in the brain, including the parabrachial nucleus (PB) and the periaqueductal gray (PAG). While neonatal spino-PB neurons are more than twice as likely to exhibit spontaneous activity compared to spino-PAG neurons, the underlying mechanisms remain unclear since nothing is known about the voltage-independent (i.e. 'leak') ion channels expressed by these distinct populations during early life. To begin identifying these key leak conductances, the present study investigated the role of classical inward-rectifying K+ (Kir2) channels in the regulation of intrinsic excitability in neonatal rat spino-PB and spino-PAG neurons. The data demonstrate that a reduction in Kir2-mediated conductance by external BaCl2 significantly enhanced intrinsic membrane excitability in both groups. Similar results were observed in spino-PB neurons following Kir2 channel block with the selective antagonist ML133. In addition, voltage-clamp experiments showed that spino-PB and spino-PAG neurons express similar amounts of Kir2 current during the early postnatal period, suggesting that the differences in the prevalence of spontaneous activity between the two populations are not explained by differential expression of Kir2 channels. Overall, the results indicate that Kir2-mediated conductance tonically dampens the firing of multiple subpopulations of lamina I projection neurons during early life. Therefore, Kir2 channels are positioned to tightly shape the output of the immature spinal nociceptive circuit and thus regulate the ascending flow of nociceptive information to the developing brain, which has important functional implications for pediatric pain.
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Affiliation(s)
- Neil C Ford
- Neuroscience Graduate Program, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA; Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, 231 Albert Sabin Way, Cincinnati, OH 45267, USA
| | - Mark L Baccei
- Neuroscience Graduate Program, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267, USA; Pain Research Center, Department of Anesthesiology, University of Cincinnati Medical Center, 231 Albert Sabin Way, Cincinnati, OH 45267, USA.
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22
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Khandekar A, Springer S, Wang W, Hicks S, Weinheimer C, Diaz-Trelles R, Nerbonne JM, Rentschler S. Notch-Mediated Epigenetic Regulation of Voltage-Gated Potassium Currents. Circ Res 2016; 119:1324-1338. [PMID: 27697822 DOI: 10.1161/circresaha.116.309877] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 09/27/2016] [Accepted: 09/30/2016] [Indexed: 12/19/2022]
Abstract
RATIONALE Ventricular arrhythmias often arise from the Purkinje-myocyte junction and are a leading cause of sudden cardiac death. Notch activation reprograms cardiac myocytes to an induced Purkinje-like state characterized by prolonged action potential duration and expression of Purkinje-enriched genes. OBJECTIVE To understand the mechanism by which canonical Notch signaling causes action potential prolongation. METHODS AND RESULTS We find that endogenous Purkinje cells have reduced peak K+ current, Ito, and IK,slow when compared with ventricular myocytes. Consistent with partial reprogramming toward a Purkinje-like phenotype, Notch activation decreases peak outward K+ current density, as well as the outward K+ current components Ito,f and IK,slow. Gene expression studies in Notch-activated ventricles demonstrate upregulation of Purkinje-enriched genes Contactin-2 and Scn5a and downregulation of K+ channel subunit genes that contribute to Ito,f and IK,slow. In contrast, inactivation of Notch signaling results in increased cell size commensurate with increased K+ current amplitudes and mimics physiological hypertrophy. Notch-induced changes in K+ current density are regulated at least in part via transcriptional changes. Chromatin immunoprecipitation demonstrates dynamic RBP-J (recombination signal binding protein for immunoglobulin kappa J region) binding and loss of active histone marks on K+ channel subunit promoters with Notch activation, and similar transcriptional and epigenetic changes occur in a heart failure model. Interestingly, there is a differential response in Notch target gene expression and cellular electrophysiology in left versus right ventricular cardiac myocytes. CONCLUSIONS In summary, these findings demonstrate a novel mechanism for regulation of voltage-gated potassium currents in the setting of cardiac pathology and may provide a novel target for arrhythmia drug design.
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Affiliation(s)
- Aditi Khandekar
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Steven Springer
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Wei Wang
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Stephanie Hicks
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Carla Weinheimer
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | | | - Jeanne M Nerbonne
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Stacey Rentschler
- Department of Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, 63110, USA
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23
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Abstract
Exercise-induced cardiac remodeling is typically an adaptive response associated with cardiac myocyte hypertrophy and renewal, increased cardiac myocyte contractility, sarcomeric remodeling, cell survival, metabolic and mitochondrial adaptations, electrical remodeling, and angiogenesis. Initiating stimuli/triggers of cardiac remodeling include increased hemodynamic load, increased sympathetic activity, and the release of hormones and growth factors. Prolonged and strenuous exercise may lead to maladaptive exercise-induced cardiac remodeling including cardiac dysfunction and arrhythmia. In addition, this article describes novel therapeutic approaches for the treatment of heart failure that target mechanisms responsible for adaptive exercise-induced cardiac remodeling, which are being developed and tested in preclinical models.
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Affiliation(s)
- Bianca C Bernardo
- Baker IDI Heart and Diabetes Institute, Cardiac Hypertrophy Laboratory, PO Box 6492, Melbourne, VIC 3004, Australia
| | - Julie R McMullen
- Baker IDI Heart and Diabetes Institute, Cardiac Hypertrophy Laboratory, PO Box 6492, Melbourne, VIC 3004, Australia; Department of Medicine, Central Clinical School, Monash University, 99 Commercial Road, Melbourne, VIC 3004, Australia; Department of Physiology, Monash University, Wellington Road, Clayton, VIC 3800, Australia.
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24
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Abstract
Heart disease produces substantial remodeling of K(+) channels that in general promotes arrhythmia occurrence. In the case of ventricular arrhythmias, K(+) channel remodeling contributes to the arrhythmic risk and increases vulnerability to torsades de pointes with K(+) channel inhibiting drugs. Atrial K(+) channel remodeling caused by atrial fibrillation promotes arrhythmia stability and presents opportunities for the development of new drugs targeting atrial inward rectifier K(+) currents. A better understanding of K(+) channel remodeling will help clinicians to appreciate arrhythmia mechanisms and determinants in a variety of clinical situations and to better manage arrhythmia therapy in patients with heart disease.
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Affiliation(s)
- Vincent Algalarrondo
- Department of Medicine, Research Center, Montreal Heart Institute, University of Montreal, 5000 Belanger Street East, Montreal, Quebec H1T 1C8, Canada; Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir-William-Osler, Montréal, Québec H3G 1Y6, Canada; Faculty of Medicine, University Duisburg-Essen, Hufelandstr. 55, Essen 45122, Germany
| | - Stanley Nattel
- Department of Medicine, Research Center, Montreal Heart Institute, University of Montreal, 5000 Belanger Street East, Montreal, Quebec H1T 1C8, Canada; Department of Pharmacology and Therapeutics, McGill University, 3655 Promenade Sir-William-Osler, Montréal, Québec H3G 1Y6, Canada; Faculty of Medicine, University Duisburg-Essen, Hufelandstr. 55, Essen 45122, Germany.
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25
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Hassinen M, Haverinen J, Vornanen M. Molecular basis and drug sensitivity of the delayed rectifier (IKr) in the fish heart. Comp Biochem Physiol C Toxicol Pharmacol 2015. [PMID: 26215639 DOI: 10.1016/j.cbpc.2015.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Fishes are increasingly used as models for human cardiac diseases, creating a need for a better understanding of the molecular basis of fish cardiac ion currents. To this end we cloned KCNH6 channel of the crucian carp (Carassius carassius) that produces the rapid component of the delayed rectifier K(+) current (IKr), the main repolarising current of the fish heart. KCNH6 (ccErg2) was the main isoform of the Kv11 potassium channel family with relative transcript levels of 98.9% and 99.6% in crucian carp atrium and ventricle, respectively. KCNH2 (ccErg1), an orthologue to human cardiac Erg (Herg) channel, was only slightly expressed in the crucian carp heart. The native atrial IKr and the cloned ccErg2 were inhibited by similar concentrations of verapamil, terfenadine and KB-R7943 (P>0.05), while the atrial IKr was about an order of magnitude more sensitive to E-4031 than ccErg2 (P<0.05) suggesting that some accessory β-subunits may be involved. Sensitivity of the crucian carp atrial IKr to E-4031, terfenadine and KB-R7943 was similar to what has been reported for the Herg channel. In contrast, the sensitivity of the crucian carp IKr to verapamil was approximately 30 times higher than the previously reported values for the Herg current. In conclusion, the cardiac IKr is produced by non-orthologous gene products in fish (Erg2) and mammalian hearts (Erg1) and some marked differences exist in drug sensitivity between fish and mammalian Erg1/2 which need to be taken into account when using fish heart as a model for human heart.
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Affiliation(s)
- Minna Hassinen
- University of Eastern Finland, Department of Biology, P.O. Box 111, 80101 Joensuu, Finland.
| | - Jaakko Haverinen
- University of Eastern Finland, Department of Biology, P.O. Box 111, 80101 Joensuu, Finland
| | - Matti Vornanen
- University of Eastern Finland, Department of Biology, P.O. Box 111, 80101 Joensuu, Finland
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26
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Walton RD, Jones SA, Rostron KA, Kayani AC, Close GL, McArdle A, Lancaster MK. Interactions of Short-Term and Chronic Treadmill Training With Aging of the Left Ventricle of the Heart. J Gerontol A Biol Sci Med Sci 2015; 71:1005-13. [PMID: 26248561 PMCID: PMC4945880 DOI: 10.1093/gerona/glv093] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 05/22/2015] [Indexed: 02/06/2023] Open
Abstract
With aging, there is a decline in cardiac function accompanying increasing risk of arrhythmias. These effects are likely to be mechanistically associated with age-associated changes in calcium regulation within cardiac myocytes. Previous studies suggest that lifelong exercise can potentially reduce age-associated changes in the heart. Although exercise itself is associated with changes in cardiac function, little is known about the interactions of aging and exercise with respect to myocyte calcium regulation. To investigate this, adult (12 months) and old (24 months) C57/Bl6 mice were trained using moderate-intensity treadmill running. In response to 10 weeks’ training, comparable cardiac hypertrophic responses were observed, although aging independently associated with additional cardiac hypertrophy. Old animals also showed increased L- and T-type calcium channels, the sodium–calcium exchange, sarcoendoplasmic reticulum calcium ATPase, and collagen (by 50%, 92%, 66%, 88%, and 113% respectively). Short-term exercise training increased D-type and T-type calcium channels in old animals only, whereas an increase in sodium–calcium exchange was seen only in adult animals. Long-term (12 months) training generally opposed the effects of aging. Significant hypertrophy remained in long-term trained old animals, but levels of sarcoendoplasmic reticulum calcium ATPase, sodium–calcium exchange, and collagen were not significantly different from those found in the adult trained animals.
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Affiliation(s)
| | | | | | - Anna C Kayani
- Institute of Ageing & Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool
| | - Graeme L Close
- Institute of Ageing & Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool
| | - Anne McArdle
- Institute of Ageing & Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool
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27
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Yang KC, Nerbonne JM. Mechanisms contributing to myocardial potassium channel diversity, regulation and remodeling. Trends Cardiovasc Med 2015; 26:209-18. [PMID: 26391345 DOI: 10.1016/j.tcm.2015.07.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 07/11/2015] [Accepted: 07/12/2015] [Indexed: 01/19/2023]
Abstract
In the mammalian heart, multiple types of K(+) channels contribute to the control of cardiac electrical and mechanical functioning through the regulation of resting membrane potentials, action potential waveforms and refractoriness. There are similarly vast arrays of K(+) channel pore-forming and accessory subunits that contribute to the generation of functional myocardial K(+) channel diversity. Maladaptive remodeling of K(+) channels associated with cardiac and systemic diseases results in impaired repolarization and increased propensity for arrhythmias. Here, we review the diverse transcriptional, post-transcriptional, post-translational, and epigenetic mechanisms contributing to regulating the expression, distribution, and remodeling of cardiac K(+) channels under physiological and pathological conditions.
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Affiliation(s)
- Kai-Chien Yang
- Department of Pharmacology, National Taiwan University, Taipei, Taiwan; Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
| | - Jeanne M Nerbonne
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO; Internal Medicine, Washington University School of Medicine, St. Louis, MO; Cardiovascular Division, Washington University School of Medicine, St. Louis, MO.
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28
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Yang KC, Kyle JW, Makielski JC, Dudley SC. Mechanisms of sudden cardiac death: oxidants and metabolism. Circ Res 2015; 116:1937-55. [PMID: 26044249 PMCID: PMC4458707 DOI: 10.1161/circresaha.116.304691] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Accepted: 02/09/2015] [Indexed: 02/07/2023]
Abstract
Ventricular arrhythmia is the leading cause of sudden cardiac death (SCD). Deranged cardiac metabolism and abnormal redox state during cardiac diseases foment arrhythmogenic substrates through direct or indirect modulation of cardiac ion channel/transporter function. This review presents current evidence on the mechanisms linking metabolic derangement and excessive oxidative stress to ion channel/transporter dysfunction that predisposes to ventricular arrhythmias and SCD. Because conventional antiarrhythmic agents aiming at ion channels have proven challenging to use, targeting arrhythmogenic metabolic changes and redox imbalance may provide novel therapeutics to treat or prevent life-threatening arrhythmias and SCD.
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Affiliation(s)
- Kai-Chien Yang
- From the Department of Pharmacology (K.-C.Y.) and Division of Cardiology, Department of Internal Medicine (K.-C.Y.), National Taiwan University Hospital, Taipei, Taiwan; Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison (J.W.K., J.C.M.); and Lifespan Cardiovascular Institute, the Providence VA Medical Center, and Brown University, RI (S.C.D.)
| | - John W Kyle
- From the Department of Pharmacology (K.-C.Y.) and Division of Cardiology, Department of Internal Medicine (K.-C.Y.), National Taiwan University Hospital, Taipei, Taiwan; Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison (J.W.K., J.C.M.); and Lifespan Cardiovascular Institute, the Providence VA Medical Center, and Brown University, RI (S.C.D.)
| | - Jonathan C Makielski
- From the Department of Pharmacology (K.-C.Y.) and Division of Cardiology, Department of Internal Medicine (K.-C.Y.), National Taiwan University Hospital, Taipei, Taiwan; Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison (J.W.K., J.C.M.); and Lifespan Cardiovascular Institute, the Providence VA Medical Center, and Brown University, RI (S.C.D.).
| | - Samuel C Dudley
- From the Department of Pharmacology (K.-C.Y.) and Division of Cardiology, Department of Internal Medicine (K.-C.Y.), National Taiwan University Hospital, Taipei, Taiwan; Division of Cardiovascular Medicine, Department of Medicine, University of Wisconsin, Madison (J.W.K., J.C.M.); and Lifespan Cardiovascular Institute, the Providence VA Medical Center, and Brown University, RI (S.C.D.).
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29
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Ballou LM, Lin RZ, Cohen IS. Control of cardiac repolarization by phosphoinositide 3-kinase signaling to ion channels. Circ Res 2015; 116:127-37. [PMID: 25552692 DOI: 10.1161/circresaha.116.303975] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Upregulation of phosphoinositide 3-kinase (PI3K) signaling is a common alteration in human cancer, and numerous drugs that target this pathway have been developed for cancer treatment. However, recent studies have implicated inhibition of the PI3K signaling pathway as the cause of a drug-induced long-QT syndrome in which alterations in several ion currents contribute to arrhythmogenic drug activity. Surprisingly, some drugs that were thought to induce long-QT syndrome by direct block of the rapid delayed rectifier (IKr) also seem to inhibit PI3K signaling, an effect that may contribute to their arrhythmogenicity. The importance of PI3K in regulating cardiac repolarization is underscored by evidence that QT interval prolongation in diabetes mellitus also may result from changes in multiple currents because of decreased insulin activation of PI3K in the heart. How PI3K signaling regulates ion channels to control the cardiac action potential is poorly understood. Hence, this review summarizes what is known about the effect of PI3K and its downstream effectors, including Akt, on sodium, potassium, and calcium currents in cardiac myocytes. We also refer to some studies in noncardiac cells that provide insight into potential mechanisms of ion channel regulation by this signaling pathway in the heart. Drug development and safety could be improved with a better understanding of the mechanisms by which PI3K regulates cardiac ion channels and the extent to which PI3K inhibition contributes to arrhythmogenic susceptibility.
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Affiliation(s)
- Lisa M Ballou
- From the Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, NY (L.M.B., R.Z.L., I.S.C.); and the Medical Service, Northport VA Medical Center, NY (R.Z.L.)
| | - Richard Z Lin
- From the Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, NY (L.M.B., R.Z.L., I.S.C.); and the Medical Service, Northport VA Medical Center, NY (R.Z.L.).
| | - Ira S Cohen
- From the Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, NY (L.M.B., R.Z.L., I.S.C.); and the Medical Service, Northport VA Medical Center, NY (R.Z.L.).
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30
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Waks JW, Soliman EZ, Henrikson CA, Sotoodehnia N, Han L, Agarwal SK, Arking DE, Siscovick DS, Solomon SD, Post WS, Josephson ME, Coresh J, Tereshchenko LG. Beat-to-beat spatiotemporal variability in the T vector is associated with sudden cardiac death in participants without left ventricular hypertrophy: the Atherosclerosis Risk in Communities (ARIC) Study. J Am Heart Assoc 2015; 4:e001357. [PMID: 25600143 PMCID: PMC4330061 DOI: 10.1161/jaha.114.001357] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Background Despite advances in prevention and treatment of cardiovascular disease, sudden cardiac death (SCD) remains a clinical challenge. Risk stratification in the general population is needed. Methods and Results Beat‐to‐beat spatiotemporal variability in the T vector was measured as the mean angle between consecutive T‐wave vectors (mean TT′ angle) on standard 12‐lead ECGs in 14 024 participants in the Atherosclerosis Risk in Communities (ARIC) study. Subjects with left ventricular hypertrophy, atrial arrhythmias, frequent ectopy, ventricular pacing, or QRS duration ≥120 ms were excluded. The mean spatial TT′ angle was 5.21±3.55°. During a median of 14 years of follow‐up, 235 SCDs occurred (1.24 per 1000 person‐years). After adjustment for demographics, coronary heart disease risk factors, and known ECG markers for SCD, mean TT′ angle was independently associated with SCD (hazard ratio 1.089; 95% CI 1.044 to 1.137; P<0.0001). A mean TT′ angle >90th percentile (>9.57°) was associated with a 2‐fold increase in the hazard for SCD (hazard ratio 2.01; 95% CI 1.28 to 3.16; P=0.002). In a subgroup of patients with T‐vector amplitude ≥0.2 mV, the association with SCD was almost twice as strong (hazard ratio 3.92; 95% CI 1.91 to 8.05; P<0.0001). A significant interaction between mean TT′ angle and age was found: TT′ angle was associated with SCD in participants aged <55 years (hazard ratio 1.096; 95% CI 0.043 to 1.152; P<0.0001) but not in participants aged ≥55 years (Pinteraction=0.009). Conclusions In a large, prospective, community‐based cohort of left ventricular hypertrophy–free participants, increased beat‐to‐beat spatiotemporal variability in the T vector, as assessed by increasing TT′ angle, was associated with SCD.
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Affiliation(s)
- Jonathan W Waks
- Division of Cardiovascular Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (J.W.W., M.E.J.)
| | - Elsayed Z Soliman
- Epidemiological Cardiology Research Center (EPICARE), Division of Public Health Sciences and Department of Medicine, Cardiology Section, Wake Forest School of Medicine, Winston Salem, NC (E.Z.S.)
| | - Charles A Henrikson
- Knight Cardiovascular Institute, Oregon Health & Science University, Portland, OR (C.A.H., L.G.T.)
| | | | - Lichy Han
- Whitening School of Engineering, Johns Hopkins University, Baltimore, MD (L.H.)
| | - Sunil K Agarwal
- Department of Epidemiology and Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins School of Public Health, Baltimore, MD (S.K.A., J.C.)
| | - Dan E Arking
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD (D.E.A.)
| | - David S Siscovick
- University of Washington, Seattle, WA (N.S., D.S.S.) The New York Academy of Medicine, New York, NY (D.S.S.)
| | - Scott D Solomon
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA (S.D.S.)
| | - Wendy S Post
- Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD (W.S.P., L.G.T.)
| | - Mark E Josephson
- Division of Cardiovascular Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA (J.W.W., M.E.J.)
| | - Josef Coresh
- Department of Epidemiology and Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins School of Public Health, Baltimore, MD (S.K.A., J.C.)
| | - Larisa G Tereshchenko
- Knight Cardiovascular Institute, Oregon Health & Science University, Portland, OR (C.A.H., L.G.T.) Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD (W.S.P., L.G.T.)
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31
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Ednie AR, Bennett ES. Reduced sialylation impacts ventricular repolarization by modulating specific K+ channel isoforms distinctly. J Biol Chem 2014; 290:2769-83. [PMID: 25525262 DOI: 10.1074/jbc.m114.605139] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Voltage-gated K(+) channels (Kv) are responsible for repolarizing excitable cells and can be heavily glycosylated. Cardiac Kv activity is indispensable where even minimal reductions in function can extend action potential duration, prolong QT intervals, and ultimately contribute to life-threatening arrhythmias. Diseases such as congenital disorders of glycosylation often cause significant cardiac phenotypes that can include arrhythmias. Here we investigated the impact of reduced sialylation on ventricular repolarization through gene deletion of the sialyltransferase ST3Gal4. ST3Gal4-deficient mice (ST3Gal4(-/-)) had prolonged QT intervals with a concomitant increase in ventricular action potential duration. Ventricular apex myocytes isolated from ST3Gal4(-/-) mice demonstrated depolarizing shifts in activation gating of the transient outward (Ito) and delayed rectifier (IKslow) components of K(+) current with no change in maximum current densities. Consistently, similar protein expression levels of the three Kv isoforms responsible for Ito and IKslow were measured for ST3Gal4(-/-) versus controls. However, novel non-enzymatic sialic acid labeling indicated a reduction in sialylation of ST3Gal4(-/-) ventricular Kv4.2 and Kv1.5, which contribute to Ito and IKslow, respectively. Thus, we describe here a novel form of regulating cardiac function through the activities of a specific glycogene product. Namely, reduced ST3Gal4 activity leads to a loss of isoform-specific Kv sialylation and function, thereby limiting Kv activity during the action potential and decreasing repolarization rate, which likely contributes to prolonged ventricular repolarization. These studies elucidate a novel role for individual glycogene products in contributing to a complex network of cardiac regulation under normal and pathologic conditions.
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Affiliation(s)
- Andrew R Ednie
- From the Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
| | - Eric S Bennett
- From the Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
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32
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Gómez-Hurtado N, Fernández-Velasco M, Fernández-Alfonso MS, Boscá L, Delgado C. Prolonged leptin treatment increases transient outward K⁺ current via upregulation of Kv4.2 and Kv4.3 channel subunits in adult rat ventricular myocytes. Pflugers Arch 2014; 466:903-14. [PMID: 24046152 DOI: 10.1007/s00424-013-1348-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 08/30/2013] [Accepted: 08/30/2013] [Indexed: 02/07/2023]
Abstract
Circulating leptin levels are elevated in obesity and hyperleptinaemia has been postulated to be an independent risk factor for the development of cardiovascular diseases. Although many studies have been published on the mechanisms involved in the effects of leptin on cardiac function and pathological remodeling, scarce information is currently available analyzing the influence of prolonged leptin treatment on ionic cardiac channels remodeling in adult ventricular myocytes. Enzymatically isolated adult rat ventricular myocytes were treated with leptin or vehicle for 48h. Real-Time RT-PCR were used to analyze mRNA expression of Kir2.1, Cav1.2, Cav 3.1, Kv4.2 and Kv4.3 α-subunits and KChIP2 auxiliary subunit. The fast transient outward potassium channels (Itof) α-subunits Kv4.2, Kv4.3 and KChIP2 were analyzed by Western-blot. The fast transient outward potassium current and the action potentials were recorded in isolated myocytes by the whole-cell patch-clamp technique. Leptin treatment induced an up-regulation of Kv4.2, Kv4.3 and KChIP2 subunits mRNA expression. However, transcriptional levels of Kir2.1, Cav1.2, or Cav3.1 α-subunit channels were unmodified by leptin. Protein expression levels of Kv4.2, Kv4.3 and KChIP2 subunits were also increased by leptin. The electrophysiological study showed that leptin increases the fast transient outward potassium current amplitudes and densities shortening action potential duration. In addition, leptin activated Akt signaling in cardiomyocytes and this mechanism was involved in the effect of leptin on Itof channels. In conclusión, leptin increases both the expression and function of Itof channels in adult ventricular myocytes and this mechanism involves Akt signaling. Altogether these data suggest that leptin could exert beneficial or detrimental effects depending on the initial ventricular myocyte repolarizing reserve.
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MESH Headings
- Action Potentials
- Animals
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Channels, T-Type/genetics
- Calcium Channels, T-Type/metabolism
- Cells, Cultured
- Heart Ventricles/cytology
- Heart Ventricles/metabolism
- Kv Channel-Interacting Proteins/genetics
- Kv Channel-Interacting Proteins/metabolism
- Leptin/pharmacology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/physiology
- Potassium/metabolism
- Proto-Oncogene Proteins c-akt/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats
- Shal Potassium Channels/genetics
- Shal Potassium Channels/metabolism
- Up-Regulation
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Affiliation(s)
- Nieves Gómez-Hurtado
- Departamento de Farmacología, Facultad de Medicina, Universidad Complutense de Madrid (UCM), 28040, Madrid, Spain
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Yang KC, Yamada KA, Patel AY, Topkara VK, George I, Cheema FH, Ewald GA, Mann DL, Nerbonne JM. Deep RNA sequencing reveals dynamic regulation of myocardial noncoding RNAs in failing human heart and remodeling with mechanical circulatory support. Circulation 2014; 129:1009-21. [PMID: 24429688 DOI: 10.1161/circulationaha.113.003863] [Citation(s) in RCA: 332] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Microarrays have been used extensively to profile transcriptome remodeling in failing human heart, although the genomic coverage provided is limited and fails to provide a detailed picture of the myocardial transcriptome landscape. Here, we describe sequencing-based transcriptome profiling, providing comprehensive analysis of myocardial mRNA, microRNA (miRNA), and long noncoding RNA (lncRNA) expression in failing human heart before and after mechanical support with a left ventricular (LV) assist device (LVAD). METHODS AND RESULTS Deep sequencing of RNA isolated from paired nonischemic (NICM; n=8) and ischemic (ICM; n=8) human failing LV samples collected before and after LVAD and from nonfailing human LV (n=8) was conducted. These analyses revealed high abundance of mRNA (37%) and lncRNA (71%) of mitochondrial origin. miRNASeq revealed 160 and 147 differentially expressed miRNAs in ICM and NICM, respectively, compared with nonfailing LV. Among these, only 2 (ICM) and 5 (NICM) miRNAs are normalized with LVAD. RNASeq detected 18 480, including 113 novel, lncRNAs in human LV. Among the 679 (ICM) and 570 (NICM) lncRNAs differentially expressed with heart failure, ≈10% are improved or normalized with LVAD. In addition, the expression signature of lncRNAs, but not miRNAs or mRNAs, distinguishes ICM from NICM. Further analysis suggests that cis-gene regulation represents a major mechanism of action of human cardiac lncRNAs. CONCLUSIONS The myocardial transcriptome is dynamically regulated in advanced heart failure and after LVAD support. The expression profiles of lncRNAs, but not mRNAs or miRNAs, can discriminate failing hearts of different pathologies and are markedly altered in response to LVAD support. These results suggest an important role for lncRNAs in the pathogenesis of heart failure and in reverse remodeling observed with mechanical support.
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Affiliation(s)
- Kai-Chien Yang
- Department of Developmental Biology (K.-C.Y., J.M.N.) and Center for Cardiovascular Research, Division of Cardiology, Department of Internal Medicine (K.A.Y., A.Y.P., V.K.T., G.A.E., D.L.M.), Washington University Medical School, St. Louis, MO; Division of Cardiothoracic Surgery, New York Presbyterian Hospital, Columbia University College of Physicians and Surgeons, New York, NY (I.G.); and Department of Surgery, University of Maryland School of Medicine, Baltimore (F.H.C.). Dr Yang's current affiliation is the Department of Pharmacology, National Taiwan University School of Medicine, Taipei, Taiwan
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Lu Z, Jiang YP, Wu CYC, Ballou LM, Liu S, Carpenter ES, Rosen MR, Cohen IS, Lin RZ. Increased persistent sodium current due to decreased PI3K signaling contributes to QT prolongation in the diabetic heart. Diabetes 2013; 62:4257-65. [PMID: 23974924 PMCID: PMC3837031 DOI: 10.2337/db13-0420] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Diabetes is an independent risk factor for sudden cardiac death and ventricular arrhythmia complications of acute coronary syndrome. Prolongation of the QT interval on the electrocardiogram is also a risk factor for arrhythmias and sudden death, and the increased prevalence of QT prolongation is an independent risk factor for cardiovascular death in diabetic patients. The pathophysiological mechanisms responsible for this lethal complication are poorly understood. Diabetes is associated with a reduction in phosphoinositide 3-kinase (PI3K) signaling, which regulates the action potential duration (APD) of individual myocytes and thus the QT interval by altering multiple ion currents, including the persistent sodium current INaP. Here, we report a mechanism for diabetes-induced QT prolongation that involves an increase in INaP caused by defective PI3K signaling. Cardiac myocytes of mice with type 1 or type 2 diabetes exhibited an increase in APD that was reversed by expression of constitutively active PI3K or intracellular infusion of phosphatidylinositol 3,4,5-trisphosphate (PIP3), the second messenger produced by PI3K. The diabetic myocytes also showed an increase in INaP that was reversed by activated PI3K or PIP3. The increases in APD and INaP in myocytes translated into QT interval prolongation for both types of diabetic mice. The long QT interval of type 1 diabetic hearts was shortened by insulin treatment ex vivo, and this effect was blocked by a PI3K inhibitor. Treatment of both types of diabetic mouse hearts with an INaP blocker also shortened the QT interval. These results indicate that downregulation of cardiac PI3K signaling in diabetes prolongs the QT interval at least in part by causing an increase in INaP. This mechanism may explain why the diabetic population has an increased risk of life-threatening arrhythmias.
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Affiliation(s)
- Zhongju Lu
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, New York
| | - Ya-Ping Jiang
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, New York
| | - Chia-Yen C. Wu
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, New York
| | - Lisa M. Ballou
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, New York
| | - Shengnan Liu
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, New York
| | - Eileen S. Carpenter
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York
| | - Michael R. Rosen
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, New York
- Department of Pharmacology, Columbia University, New York, New York
| | - Ira S. Cohen
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, New York
- Corresponding author: Ira S. Cohen, , or Richard Z. Lin,
| | - Richard Z. Lin
- Department of Physiology and Biophysics and the Institute for Molecular Cardiology, Stony Brook University, Stony Brook, New York
- Medical Service, Northport VA Medical Center, Northport, New York
- Corresponding author: Ira S. Cohen, , or Richard Z. Lin,
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Lin X, Liang HY, Pinheiro A, Dimaano V, Sorensen L, Aon M, Tereshchenko LG, Chen Y, Xiang M, Abraham TP, Abraham MR. Electromechanical relationship in hypertrophic cardiomyopathy. J Cardiovasc Transl Res 2013; 6:604-15. [PMID: 23771430 DOI: 10.1007/s12265-013-9481-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 06/04/2013] [Indexed: 01/27/2023]
Abstract
We examined whether there is a relationship between repolarization abnormalities on electrocardiography (EKG) and deformation abnormalities by echocardiography. Analysis of baseline EKGs and mechanical (echo-based deformation) changes was performed in 128 patients with a clinical diagnosis of hypertrophic cardiomyopathy (HCM). Patients with left ventricular hypertrophy (LVH) or repolarization abnormalities had higher septal thickness when compared to patients with normal EKG. Patients with EKG evidence of LVH or QTc prolongation had lower systolic velocity, systolic strain, systolic strain rate, late diastolic velocity, and late diastolic strain rate than patients with a normal EKG. Patients with strain pattern or ST depression/T-wave inversion had lower systolic velocity, systolic strain, systolic strain rate, early diastolic velocity, and late diastolic velocity when compared to patients with normal EKGs. LVH and repolarization abnormalities on surface EKG are markers of impaired systolic and diastolic mechanics in HCM.
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Affiliation(s)
- Xiaoping Lin
- Division of Cardiology, Johns Hopkins University School of Medicine, 720 Rutland Ave, Ross 871, Baltimore, MD 21201, USA
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36
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Working out the heart: functional remodeling by endurance exercise training. J Mol Cell Cardiol 2013; 60:47-9. [PMID: 23579023 DOI: 10.1016/j.yjmcc.2013.02.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Accepted: 02/13/2013] [Indexed: 10/27/2022]
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McLean BA, Zhabyeyev P, Pituskin E, Paterson I, Haykowsky MJ, Oudit GY. PI3K Inhibitors as Novel Cancer Therapies: Implications for Cardiovascular Medicine. J Card Fail 2013; 19:268-82. [DOI: 10.1016/j.cardfail.2013.02.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 02/07/2013] [Accepted: 02/27/2013] [Indexed: 01/09/2023]
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38
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Neuronal nitric oxide synthase is indispensable for the cardiac adaptive effects of exercise. Basic Res Cardiol 2013; 108:332. [PMID: 23377961 DOI: 10.1007/s00395-013-0332-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 01/22/2013] [Accepted: 01/23/2013] [Indexed: 10/27/2022]
Abstract
Exercise results in beneficial adaptations of the heart that can be directly observed at the ventricular myocyte level. However, the molecular mechanism(s) responsible for these adaptations are not well understood. Interestingly, signaling via neuronal nitric oxide synthase (NOS1) within myocytes results in similar effects as exercise. Thus, the objective was to define the role NOS1 plays in the exercise-induced beneficial contractile effects in myocytes. After an 8-week aerobic interval training program, exercise-trained (Ex) mice had higher VO(2max) and cardiac hypertrophy compared to sedentary (Sed) mice. Ventricular myocytes from Ex mice had increased NOS1 expression and nitric oxide production compared to myocytes from Sed mice. Remarkably, acute NOS1 inhibition normalized the enhanced contraction (shortening and Ca(2+) transients) in Ex myocytes to Sed levels. The NOS1 effect on contraction was mediated via greater Ca(2+) cycling that resulted from increased phospholamban phosphorylation. Intriguingly, a similar aerobic interval training program on NOS1 knockout mice failed to produce any beneficial cardiac adaptations (VO(2max), hypertrophy, and contraction). These data demonstrate that the beneficial cardiac adaptations observed after exercise training were mediated via enhanced NOS1 signaling. Therefore, it is likely that beneficial effects of exercise may be mimicked by the interventions that increase NOS1 signaling. This pathway may provide a potential novel therapeutic target in cardiac patients who are unable or unwilling to exercise.
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Tiscornia GC, Moretta R, Argenziano MA, Amorena CE, Garcia Gras EA. Inhibition of connexin 43 in cardiac muscle during intense physical exercise. Scand J Med Sci Sports 2012. [PMID: 23206241 DOI: 10.1111/sms.12017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Endurance training is accompanied by important adaptations in both cardiovascular and autonomic nervous systems. Previous works have shown that the main component of gap junctions in the ventricular myocardium (connexin 43 (Cx43) can be regulated by adrenergic stimulus. On the other hand, training raises vagal and decreases sympathetic tone, while augmenting myocardial sensitivity to sympathetic stimulation during exercise. We therefore evaluated the regulation of Cx43 expression by sympathetic tone during exercise in trained and sedentary mice. Training induced an increase in the protein level of Cx43 by 45-70% under resting conditions. The expression of Cx43 was inhibited in trained but not in untrained mice in response to a 60 min exercise bout. Normal basal expression was restored after 60 min of resting. Cx43 reached a minimum that was not different from basal expression in untrained mice. In accordance, electrocardiography and action potential analysis did not reveal major electrophysiological implications for the drop in Cx43 abundance in trained-exercise mice. We prevented Cx43 inhibition using propranolol, and observed increased basal mRNA levels of β-adrenergic receptors without significant changes in the ratio β1 to β2. In conclusion, we showed that Cx43 expression is transiently inhibited by β-adrenergic stimulus in trained mice during acute exercise.
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Affiliation(s)
- G C Tiscornia
- CESyMA, ECyT, National University of San Martin, San Martin, Buenos Aires, Argentina
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I(A) channels encoded by Kv1.4 and Kv4.2 regulate neuronal firing in the suprachiasmatic nucleus and circadian rhythms in locomotor activity. J Neurosci 2012; 32:10045-52. [PMID: 22815518 DOI: 10.1523/jneurosci.0174-12.2012] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Neurons in the suprachiasmatic nucleus (SCN) display coordinated circadian changes in electrical activity that are critical for daily rhythms in physiology, metabolism, and behavior. SCN neurons depolarize spontaneously and fire repetitively during the day and hyperpolarize, drastically reducing firing rates, at night. To explore the hypothesis that rapidly activating and inactivating A-type (I(A)) voltage-gated K(+) (Kv) channels, which are also active at subthreshold membrane potentials, are critical regulators of the excitability of SCN neurons, we examined locomotor activity and SCN firing in mice lacking Kv1.4 (Kv1.4(-/-)), Kv4.2 (Kv4.2(-/-)), or Kv4.3 (Kv4.3(-/-)), the pore-forming (α) subunits of I(A) channels. Mice lacking either Kv1.4 or Kv4.2 α subunits have markedly shorter (0.5 h) periods of locomotor activity than wild-type (WT) mice. In vitro extracellular multi-electrode recordings revealed that Kv1.4(-/-) and Kv4.2(-/-) SCN neurons display circadian rhythms in repetitive firing, but with shorter periods (0.5 h) than WT cells. In contrast, the periods of wheel-running activity in Kv4.3(-/-) mice and firing in Kv4.3(-/-) SCN neurons were indistinguishable from WT animals and neurons. Quantitative real-time PCR revealed that the transcripts encoding all three Kv channel α subunits, Kv1.4, Kv4.2, and Kv4.3, are expressed constitutively throughout the day and night in the SCN. Together, these results demonstrate that Kv1.4- and Kv4.2-encoded I(A) channels regulate the intrinsic excitability of SCN neurons during the day and night and determine the period and amplitude of circadian rhythms in SCN neuron firing and locomotor behavior.
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Increased mechanically-induced ectopy in the hypertrophied heart. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2012; 110:331-9. [DOI: 10.1016/j.pbiomolbio.2012.07.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 07/11/2012] [Indexed: 02/04/2023]
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Yang KC, Tseng YT, Nerbonne JM. Exercise training and PI3Kα-induced electrical remodeling is independent of cellular hypertrophy and Akt signaling. J Mol Cell Cardiol 2012; 53:532-41. [PMID: 22824041 PMCID: PMC3432661 DOI: 10.1016/j.yjmcc.2012.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Revised: 06/30/2012] [Accepted: 07/02/2012] [Indexed: 12/25/2022]
Abstract
In contrast with pathological hypertrophy, exercise-induced physiological hypertrophy is not associated with electrical abnormalities or increased arrhythmia risk. Recent studies have shown that increased cardiac-specific expression of phosphoinositide-3-kinase-α (PI3Kα), the key mediator of physiological hypertrophy, results in transcriptional upregulation of ion channel subunits in parallel with the increase in myocyte size (cellular hypertrophy) and the maintenance of myocardial excitability. The experiments here were undertaken to test the hypothesis that Akt1, which underlies PI3Kα-induced cellular hypertrophy, mediates the effects of augmented PI3Kα signaling on the transcriptional regulation of cardiac ion channels. In contrast to wild-type animals, chronic exercise (swim) training of mice (Akt1(-/-)) lacking Akt1 did not result in ventricular myocyte hypertrophy. Ventricular K(+) current amplitudes and the expression of K(+) channel subunits, however, were increased markedly in Akt1(-/-) animals with exercise training. Expression of the transcripts encoding inward (Na(+) and Ca(2+)) channel subunits were also increased in Akt1(-/-) ventricles following swim training. Additional experiments in a transgenic mouse model of inducible cardiac-specific expression of constitutively active PI3Kα (icaPI3Kα) revealed that short-term activation of PI3Kα signaling in the myocardium also led to the transcriptional upregulation of ion channel subunits. Inhibition of cardiac Akt activation with triciribine in this (inducible caPI3Kα expression) model did not prevent the upregulation of myocardial ion channel subunits. These combined observations demonstrate that chronic exercise training and enhanced PI3Kα expression/activity result in transcriptional upregulation of myocardial ion channel subunits independent of cellular hypertrophy and Akt signaling.
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Affiliation(s)
- Kai-Chien Yang
- Department of Developmental Biology, Washington University Medical School, St. Louis, Missouri
| | - Yi-Tang Tseng
- Department of Pediatrics, Women and Infant’s Hospital of Rhode Island, The Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Jeanne M. Nerbonne
- Department of Developmental Biology, Washington University Medical School, St. Louis, Missouri
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Chen Y, Csordás G, Jowdy C, Schneider TG, Csordás N, Wang W, Liu Y, Kohlhaas M, Meiser M, Bergem S, Nerbonne JM, Dorn GW, Maack C. Mitofusin 2-containing mitochondrial-reticular microdomains direct rapid cardiomyocyte bioenergetic responses via interorganelle Ca(2+) crosstalk. Circ Res 2012; 111:863-75. [PMID: 22777004 DOI: 10.1161/circresaha.112.266585] [Citation(s) in RCA: 271] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
RATIONALE Mitochondrial Ca(2+) uptake is essential for the bioenergetic feedback response through stimulation of Krebs cycle dehydrogenases. Close association of mitochondria to the sarcoplasmic reticulum (SR) may explain efficient mitochondrial Ca(2+) uptake despite low Ca(2+) affinity of the mitochondrial Ca(2+) uniporter. However, the existence of such mitochondrial Ca(2+) microdomains and their functional role are presently unresolved. Mitofusin (Mfn) 1 and 2 mediate mitochondrial outer membrane fusion, whereas Mfn2 but not Mfn1 tethers endoplasmic reticulum to mitochondria in noncardiac cells. OBJECTIVE To elucidate roles for Mfn1 and 2 in SR-mitochondrial tethering, Ca(2+) signaling, and bioenergetic regulation in cardiac myocytes. METHODS AND RESULTS Fruit fly heart tubes deficient of the Drosophila Mfn ortholog MARF had increased contraction-associated and caffeine-sensitive Ca(2+) release, suggesting a role for Mfn in SR Ca(2+) handling. Whereas cardiac-specific Mfn1 ablation had no effects on murine heart function or Ca(2+) cycling, Mfn2 deficiency decreased cardiomyocyte SR-mitochondrial contact length by 30% and reduced the content of SR-associated proteins in mitochondria-associated membranes. This was associated with decreased mitochondrial Ca(2+) uptake (despite unchanged mitochondrial membrane potential) but increased steady-state and caffeine-induced SR Ca(2+) release. Accordingly, Ca(2+)-induced stimulation of Krebs cycle dehydrogenases during β-adrenergic stimulation was hampered in Mfn2-KO but not Mfn1-KO myocytes, evidenced by oxidation of the redox states of NAD(P)H/NAD(P)(+) and FADH(2)/FAD. CONCLUSIONS Physical tethering of SR and mitochondria via Mfn2 is essential for normal interorganelle Ca(2+) signaling in the myocardium, consistent with a requirement for SR-mitochondrial Ca(2+) signaling through microdomains in the cardiomyocyte bioenergetic feedback response to physiological stress.
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Affiliation(s)
- Yun Chen
- Center for Pharmacogenomics, Department of Internal Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
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Yang KC, Ku YC, Lovett M, Nerbonne JM. Combined deep microRNA and mRNA sequencing identifies protective transcriptomal signature of enhanced PI3Kα signaling in cardiac hypertrophy. J Mol Cell Cardiol 2012; 53:101-12. [PMID: 22580345 DOI: 10.1016/j.yjmcc.2012.04.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 03/28/2012] [Accepted: 04/16/2012] [Indexed: 01/19/2023]
Abstract
The perturbation of myocardial transcriptome homeostasis is the hallmark of pathological hypertrophy, underlying the maladaptive myocardial remodeling secondary to pathological stresses. Classic and novel therapeutics that provide beneficial effects against pathological remodeling likely impact myocardial transcriptome architecture, including miRNA and mRNA expression profiles. Microarray and PCR-based technologies, although employed extensively, cannot provide adequate sequence coverage or quantitative accuracy to test this hypothesis directly. The goal of this study was to develop and exploit next-generation sequencing approaches for comprehensive and quantitative analyses of myocardial miRNAs and mRNAs to test the hypothesis that augmented phosphoinositide-3-kinase-p110α (PI3Kα) signaling in the setting of pathological hypertrophy provides beneficial effects through remodeling of the myocardial transcriptome signature. In these studies, a molecular and bioinformatic pipeline permitting comprehensive analysis and quantification of myocardial miRNA and mRNA expression with next-generation sequencing was developed and the impact of enhanced PI3Kα signaling on the myocardial transcriptome signature of pressure overload-induced pathological hypertrophy was explored. These analyses identified multiple miRNAs and mRNAs that were abnormally expressed in pathological hypertrophy and partially or completely normalized with increased PI3Kα signaling. Additionally, several novel miRNAs potentially linked to remodeling in cardiac hypertrophy were identified. Additional experiments revealed that increased PI3Kα signaling reduces cardiac fibrosis in pathological hypertrophy through modulating TGF-β signaling and miR-21 expression. In conclusion, using the approach of combined miRNA and mRNA sequencing, we identify the protective transcriptome signature of enhanced PI3Kα signaling in the context of pathological hypertrophy, and demonstrate the regulation of TGF-β/miR-21 by which enhanced PI3Kα signaling protects against cardiac fibrosis.
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Affiliation(s)
- Kai-Chien Yang
- Department of Developmental Biology, Washington University Medical School, St Louis, MO 63110-1093, USA
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Bernardo BC, Ooi JY, McMullen JR. The yin and yang of adaptive and maladaptive processes in heart failure. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/j.ddstr.2013.10.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Liu HB, Yang BF, Dong DL. Calcineurin and electrical remodeling in pathologic cardiac hypertrophy. Trends Cardiovasc Med 2011; 20:148-53. [PMID: 21742270 DOI: 10.1016/j.tcm.2010.12.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 12/13/2010] [Indexed: 10/18/2022]
Abstract
Calcineurin is a cytoplasmic Ca(2+)/calmodulin-dependent protein phosphatase that contributes to cardiac hypertrophy. Numerous studies have demonstrated that calcineurin/nuclear factor of activated T cell pathway affects the architecture of the heart under pathologic conditions, and the effects of calcineurin/nuclear factor of activated T cell pathway on cardiac hypertrophy have been well reviewed. Cardiac electrical remodeling is generally accompanied with the cardiac hypertrophy, and alteration of cardiac ion channel activity also leads to the changes of calcineurin activity and cardiac hypertrophy. Many studies have linked calcineurin with changes of a variety of ion channels, but the therapeutic approaches to target calcineurin for correcting cardiac electrical disturbance have not been formulated. Here, we review the recent progress in calcineurin and electrical remodeling in pathologic cardiac hypertrophy.
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Affiliation(s)
- Hui-Bin Liu
- Department of Pharmacology, Harbin Medical University, Harbin 150086, PR China
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Marrus SB, Cuculich PS, Wang W, Nerbonne JM. Characterization of a novel, dominant negative KCNJ2 mutation associated with Andersen-Tawil syndrome. Channels (Austin) 2011; 5:500-9. [PMID: 22186697 DOI: 10.4161/chan.5.6.18524] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Andersen-Tawil syndrome is characterized by periodic paralysis, ventricular ectopy, and dysmorphic features. Approximately 60% of patients exhibit loss-of-function mutations in KCNJ2, which encodes the inwardly rectifying K(+) channel pore forming subunit Kir2.1. Here, we report the identification of a novel KCNJ2 mutation (G211T), resulting in the amino acid substitution D71Y, in a patient presenting with signs and symptoms of Andersen-Tawil syndrome. The functional properties of the mutant subunit were characterized using voltage-clamp experiments on transiently transfected HEK-293 cells and neonatal mouse ventricular myocytes. Whole-cell current recordings of transfected HEK-293 cells demonstrated that the mutant protein Kir2.1-D71Y fails to form functional ion channels when expressed alone, but co-assembles with wild-type Kir2.1 subunits and suppresses wild-type subunit function. Further analysis revealed that current suppression requires at least two mutant subunits per channel. The D71Y mutation does not measurably affect the membrane trafficking of either the mutant or the wild-type subunit or alter the kinetic properties of the currents. Additional experiments revealed that expression of the mutant subunit suppresses native I(K1) in neonatal mouse ventricular myocytes. Simulations predict that the D71Y mutation in human ventricular myocytes will result in a mild prolongation of the action potential and potentially increase cell excitability. These experiments indicate that the Kir2.1-D71Y mutant protein functions as a dominant negative subunit resulting in reduced inwardly rectifying K(+) current amplitudes and altered cellular excitability in patients with Andersen-Tawil syndrome.
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Affiliation(s)
- Scott B Marrus
- Washington University School of Medicine; St. Louis, MO, USA.
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Yang KC, Jay PY, McMullen JR, Nerbonne JM. Enhanced cardiac PI3Kα signalling mitigates arrhythmogenic electrical remodelling in pathological hypertrophy and heart failure. Cardiovasc Res 2011; 93:252-62. [PMID: 22038742 DOI: 10.1093/cvr/cvr283] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
AIMS Cardiac hypertrophy and heart failure are associated with QT prolongation and lethal ventricular arrhythmias resulting from decreased K(+) current densities and impaired repolarization. Recent studies in mouse models of physiological cardiac hypertrophy revealed that increased phosphoinositide-3-kinase-α (PI3Kα) signalling results in the up-regulation of K(+) channels and the normalization of ventricular repolarization. The experiments here were undertaken to test the hypothesis that increased PI3Kα signalling will counteract the adverse electrophysiological remodelling associated with pathological hypertrophy and heart failure. METHODS AND RESULTS In contrast to wild-type mice, left ventricular (LV) hypertrophy, induced by transverse aortic constriction (TAC), did not result in prolongation of ventricular action potentials or QT intervals in mice with cardiac-specific expression of constitutively active PI3Kα (caPI3Kα). Indeed, repolarizing K(+) currents and K(+) channel subunit transcripts were increased in caPI3Kα + TAC LV myocytes in proportion to the TAC-induced cellular hypertrophy. Congestive heart failure in a transgenic model of dilated cardiomyopathy model is accompanied by prolonged QT intervals and ventricular action potentials, reduced K(+) currents and K(+) channel transcripts. Increased PI3Kα signalling, but not renin-angiotensin system blockade, in this model also results in increased K(+) currents and improved ventricular repolarization. CONCLUSION In the setting of pathological hypertrophy or heart failure, enhanced PI3Kα signalling results in the up-regulation of K(+) channel subunits, normalization of K(+) current densities and preserved ventricular function. Augmentation of PI3Kα signalling, therefore, may be a useful and unique strategy to protect against the increased risk of ventricular arrhythmias and sudden death associated with cardiomyopathy.
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Affiliation(s)
- Kai-Chien Yang
- Department of Developmental Biology, Washington University Medical School, 660 South Euclid Avenue Box 8103, St Louis, MO 63110-1093, USA
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Naud P, Guasch E, Nattel S. Physiological versus pathological cardiac electrical remodelling: potential basis and relevance to clinical management. J Physiol 2010; 588:4855-6. [PMID: 21173087 PMCID: PMC3020321 DOI: 10.1113/jphysiol.2010.202556] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Patrice Naud
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal.
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