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Zhao L, Yang Q, Tang Y, You Q, Guo X. Design, synthesis, and biological evaluation of arylmethylpiperidines as Kv1.5 potassium channel inhibitors. J Enzyme Inhib Med Chem 2022; 37:462-471. [PMID: 35012386 PMCID: PMC8757610 DOI: 10.1080/14756366.2021.2018683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Kv1.5 potassium channel, encoded by KCNA5, is a promising target for the treatment of atrial fibrillation, one of the common arrhythmia. A new series of arylmethylpiperidines derivatives based on DDO-02001 were synthesised and evaluated for their ability to inhibit Kv1.5 channel. Among them, compound DDO-02005 showed good inhibitory activity (IC50 = 0.72 μM), preferable anti-arrhythmic effects and favoured safety. These results indicate that DDO-02005 can be a promising Kv1.5 inhibitor for further studies.
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Affiliation(s)
- Lingyue Zhao
- Jiang Su Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing, China.,Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Qian Yang
- Jiang Su Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing, China.,Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Yiqun Tang
- Department of Clinical Pharmacy, School of Basic Medical Sciences and Clinical Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Qidong You
- Jiang Su Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing, China.,Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Xiaoke Guo
- Jiang Su Key Laboratory of Drug Design and Optimization, China Pharmaceutical University, Nanjing, China.,Department of Medicinal Chemistry, School of Pharmacy, China Pharmaceutical University, Nanjing, China
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2
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Romanowicz J, Guerrelli D, Dhari Z, Mulvany C, Reilly M, Swift L, Vasandani N, Ramadan M, Leatherbury L, Ishibashi N, Posnack NG. Chronic perinatal hypoxia delays cardiac maturation in a mouse model for cyanotic congenital heart disease. Am J Physiol Heart Circ Physiol 2021; 320:H1873-H1886. [PMID: 33739154 DOI: 10.1152/ajpheart.00870.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Compared with acyanotic congenital heart disease (CHD), cyanotic CHD has an increased risk of lifelong mortality and morbidity. These adverse outcomes may be attributed to delayed cardiomyocyte maturation, since the transition from a hypoxic fetal milieu to oxygen-rich postnatal environment is disrupted. We established a rodent model to replicate hypoxic myocardial conditions spanning perinatal development, and tested the hypothesis that chronic hypoxia impairs cardiac development. Pregnant mice were housed in hypoxia beginning at embryonic day 16. Pups stayed in hypoxia until postnatal day (P)8 when cardiac development is nearly complete. Global gene expression was quantified at P8 and at P30, after recovering in normoxia. Phenotypic testing included electrocardiogram, echocardiogram, and ex vivo electrophysiology study. Hypoxic P8 animals were 47% smaller than controls with preserved heart size. Gene expression was grossly altered by hypoxia at P8 (1,427 genes affected), but normalized after recovery (P30). Electrocardiograms revealed bradycardia and slowed conduction velocity in hypoxic animals at P8, with noticeable resolution after recovery (P30). Notable differences that persisted after recovery (P30) included a 65% prolongation in ventricular effective refractory period, sinus node dysfunction, 23% reduction in ejection fraction, and 16% reduction in fractional shortening in animals exposed to hypoxia. We investigated the impact of chronic hypoxia on the developing heart. Perinatal hypoxia was associated with changes in gene expression and cardiac function. Persistent changes to the electrophysiological substrate and contractile function warrant further investigation and may contribute to adverse outcomes observed in the cyanotic CHD population.NEW & NOTEWORTHY We utilized a new mouse model of chronic perinatal hypoxia to simulate the hypoxic myocardial conditions present in cyanotic congenital heart disease. Hypoxia caused numerous abnormalities in cardiomyocyte gene expression, the electrophysiologic substrate of the heart, and contractile function. Taken together, alterations observed in the neonatal period suggest delayed cardiac development immediately following hypoxia.
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Affiliation(s)
- Jennifer Romanowicz
- Children's National Heart Institute, Children's National Hospital, Washington, District of Columbia
| | - Devon Guerrelli
- Children's National Heart Institute, Children's National Hospital, Washington, District of Columbia.,Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Research Institute, Washington, District of Columbia.,Department of Biomedical Engineering, George Washington University, Washington, District of Columbia
| | - Zaenab Dhari
- Center for Neuroscience Research, Children's National Research Institute, Washington, District of Columbia
| | - Colm Mulvany
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Research Institute, Washington, District of Columbia
| | - Marissa Reilly
- Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Research Institute, Washington, District of Columbia
| | - Luther Swift
- Children's National Heart Institute, Children's National Hospital, Washington, District of Columbia.,Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Research Institute, Washington, District of Columbia
| | - Nimisha Vasandani
- Center for Neuroscience Research, Children's National Research Institute, Washington, District of Columbia
| | - Manelle Ramadan
- Children's National Heart Institute, Children's National Hospital, Washington, District of Columbia.,Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Research Institute, Washington, District of Columbia
| | - Linda Leatherbury
- Children's National Heart Institute, Children's National Hospital, Washington, District of Columbia
| | - Nobuyuki Ishibashi
- Children's National Heart Institute, Children's National Hospital, Washington, District of Columbia.,Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Research Institute, Washington, District of Columbia.,Center for Neuroscience Research, Children's National Research Institute, Washington, District of Columbia.,Department of Pediatrics, George Washington University, Washington, District of Columbia.,Department of Pharmacology & Physiology, George Washington University, Washington, District of Columbia
| | - Nikki Gillum Posnack
- Children's National Heart Institute, Children's National Hospital, Washington, District of Columbia.,Sheikh Zayed Institute for Pediatric Surgical Innovation, Children's National Research Institute, Washington, District of Columbia.,Department of Pediatrics, George Washington University, Washington, District of Columbia.,Department of Pharmacology & Physiology, George Washington University, Washington, District of Columbia
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3
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Bernardi J, Aromolaran KA, Zhu H, Aromolaran AS. Circadian Mechanisms: Cardiac Ion Channel Remodeling and Arrhythmias. Front Physiol 2021; 11:611860. [PMID: 33519516 PMCID: PMC7841411 DOI: 10.3389/fphys.2020.611860] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 12/18/2020] [Indexed: 12/31/2022] Open
Abstract
Circadian rhythms are involved in many physiological and pathological processes in different tissues, including the heart. Circadian rhythms play a critical role in adverse cardiac function with implications for heart failure and sudden cardiac death, highlighting a significant contribution of circadian mechanisms to normal sinus rhythm in health and disease. Cardiac arrhythmias are a leading cause of morbidity and mortality in patients with heart failure and likely cause ∼250,000 deaths annually in the United States alone; however, the molecular mechanisms are poorly understood. This suggests the need to improve our current understanding of the underlying molecular mechanisms that increase vulnerability to arrhythmias. Obesity and its associated pathologies, including diabetes, have emerged as dangerous disease conditions that predispose to adverse cardiac electrical remodeling leading to fatal arrhythmias. The increasing epidemic of obesity and diabetes suggests vulnerability to arrhythmias will remain high in patients. An important objective would be to identify novel and unappreciated cellular mechanisms or signaling pathways that modulate obesity and/or diabetes. In this review we discuss circadian rhythms control of metabolic and environmental cues, cardiac ion channels, and mechanisms that predispose to supraventricular and ventricular arrhythmias including hormonal signaling and the autonomic nervous system, and how understanding their functional interplay may help to inform the development and optimization of effective clinical and therapeutic interventions with implications for chronotherapy.
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Affiliation(s)
- Joyce Bernardi
- Masonic Medical Research Institute, Utica, NY, United States
| | | | - Hua Zhu
- Department of Surgery, The Ohio State University Wexner Medical Center, Columbus, OH, United States
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4
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Zhang YL, Teng F, Han X, Li PB, Yan X, Guo SB, Li HH. Selective blocking of CXCR2 prevents and reverses atrial fibrillation in spontaneously hypertensive rats. J Cell Mol Med 2020; 24:11272-11282. [PMID: 32812337 PMCID: PMC7576251 DOI: 10.1111/jcmm.15694] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/03/2020] [Accepted: 07/09/2020] [Indexed: 12/17/2022] Open
Abstract
Atrial fibrillation (AF) is associated with inflammation and oxidative stress. Recently, we demonstrated that the chemokine‐receptor CXCR2 plays a critical role in the recruitment of monocytes/macrophages and the development of hypertension and cardiac remodelling. However, the role of CXCR2 in the pathogenesis of hypertensive AF remains unclear. AF was induced in Wistar‐Kyoto rats (WKYs) and spontaneously hypertensive rats (SHRs) administered with the CXCR2 inhibitor SB225002. Atrial remodelling, pathological changes and electrophysiology were examined. Our results showed that the chemokine CXCL1 and its receptor CXCR2 were markedly increased in atrial tissue of SHRs compared with WKYs. The administration of SB225002 to SHRs significantly reduced the elevation of blood pressure, AF inducibility and duration, atrial remodelling, recruitment of macrophages, superoxide production and conduction abnormalities compared with vehicle treatment. The administration of SB225002 to SHRs also reversed pre‐existing AF development, atrial remodelling, inflammation and oxidative stress. These effects were associated with the inhibition of multiple signalling pathways, including TGF‐β1/Smad2/3, NF‐κB‐P65, NOX1, NOX2, Kir2.1, Kv1.5 and Cx43. In conclusion, this study provides new evidence that blocking CXCR2 prevents and reverses the development of AF in SHRs, and suggests that CXCR2 may be a potential therapeutic target for hypertensive AF.
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Affiliation(s)
- Yun-Long Zhang
- Department of Emergency Medicine, Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Fei Teng
- Department of Emergency Medicine, Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Xiao Han
- Department of Emergency Medicine, Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Pang-Bo Li
- Department of Emergency Medicine, Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Xiao Yan
- Department of Emergency Medicine, Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Shu-Bin Guo
- Department of Emergency Medicine, Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Hui-Hua Li
- Department of Emergency Medicine, Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
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5
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Fakuade FE, Steckmeister V, Seibertz F, Gronwald J, Kestel S, Menzel J, Pronto JRD, Taha K, Haghighi F, Kensah G, Pearman CM, Wiedmann F, Teske AJ, Schmidt C, Dibb KM, El-Essawi A, Danner BC, Baraki H, Schwappach B, Kutschka I, Mason FE, Voigt N. Altered atrial cytosolic calcium handling contributes to the development of postoperative atrial fibrillation. Cardiovasc Res 2020; 117:1790-1801. [PMID: 32520995 PMCID: PMC8208741 DOI: 10.1093/cvr/cvaa162] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 05/04/2020] [Accepted: 06/04/2020] [Indexed: 01/14/2023] Open
Abstract
Aims Atrial fibrillation (AF) is a commonly occurring arrhythmia after cardiac surgery (postoperative AF, poAF) and is associated with poorer outcomes. Considering that reduced atrial contractile function is a predictor of poAF and that Ca2+ plays an important role in both excitation–contraction coupling and atrial arrhythmogenesis, this study aims to test whether alterations of intracellular Ca2+ handling contribute to impaired atrial contractility and to the arrhythmogenic substrate predisposing patients to poAF. Methods and results Right atrial appendages were obtained from patients in sinus rhythm undergoing open-heart surgery. Cardiomyocytes were investigated by simultaneous measurement of [Ca2+]i and action potentials (APs, patch-clamp). Patients were followed-up for 6 days to identify those with and without poAF. Speckle-tracking analysis of preoperative echocardiography revealed reduced left atrial contraction strain in poAF patients. At the time of surgery, cellular Ca2+ transients (CaTs) and the sarcoplasmic reticulum (SR) Ca2+ content were smaller in the poAF group. CaT decay was slower in poAF, but the decay of caffeine-induced Ca2+ transients was unaltered, suggesting preserved sodium-calcium exchanger function. In agreement, western blots revealed reduced SERCA2a expression in poAF patients but unaltered phospholamban expression/phosphorylation. Computational modelling indicated that reduced SERCA activity promotes occurrence of CaT and AP alternans. Indeed, alternans of CaT and AP occurred more often and at lower stimulation frequencies in atrial myocytes from poAF patients. Resting membrane potential and AP duration were comparable between both groups at various pacing frequencies (0.25–8 Hz). Conclusions Biochemical, functional, and modelling data implicate reduced SERCA-mediated Ca2+ reuptake into the SR as a major contributor to impaired preoperative atrial contractile function and to the pre-existing arrhythmogenic substrate in patients developing poAF.
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Affiliation(s)
- Funsho E Fakuade
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
| | - Vanessa Steckmeister
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
| | - Fitzwilliam Seibertz
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
| | - Judith Gronwald
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
| | - Stefanie Kestel
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
| | - Julia Menzel
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Molecular Biology, University Medical Centre, Humboldtallee 23, 37075 Göttingen, Germany
| | - Julius Ryan D Pronto
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
| | - Karim Taha
- Department of Cardiology, University Medical Centre, Heidelberglaan 100, 3508 GA Utrecht, The Netherlands.,Netherlands Heart Institute, Holland Heart House, Moreelsepark 1, 3511 EP Utrecht, The Netherlands
| | - Fereshteh Haghighi
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Thoracic and Cardiovascular Surgery, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - George Kensah
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Thoracic and Cardiovascular Surgery, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - Charles M Pearman
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Felix Wiedmann
- Department of Cardiology, University Medical Center Heidelberg, Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Germany
| | - Arco J Teske
- Department of Cardiology, University Medical Centre, Heidelberglaan 100, 3508 GA Utrecht, The Netherlands
| | - Constanze Schmidt
- Department of Cardiology, University Medical Center Heidelberg, Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Germany
| | - Katharine M Dibb
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Aschraf El-Essawi
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Thoracic and Cardiovascular Surgery, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,Department of Thoracic and Cardiovascular Surgery, Klinikum Braunschweig, Braunschweig, Germany
| | - Bernhard C Danner
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Thoracic and Cardiovascular Surgery, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - Hassina Baraki
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Thoracic and Cardiovascular Surgery, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - Blanche Schwappach
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Molecular Biology, University Medical Centre, Humboldtallee 23, 37075 Göttingen, Germany
| | - Ingo Kutschka
- DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany.,Department of Thoracic and Cardiovascular Surgery, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany
| | - Fleur E Mason
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
| | - Niels Voigt
- Institute of Pharmacology and Toxicology, University Medical Centre Göttingen, Robert-Koch-Straße 40, 37075 Göttingen, Germany.,DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany
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6
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Postoperative Atrial Fibrillation Following Cardiac Surgery: From Pathogenesis to Potential Therapies. Am J Cardiovasc Drugs 2020; 20:19-49. [PMID: 31502217 DOI: 10.1007/s40256-019-00365-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Postoperative atrial fibrillation (POAF) is a major complication after cardiac surgery which can lead to high rates of morbidity and mortality, an enhanced length of hospital stay, and an increased cost of care. POAF is postulated to be a multifactorial phenomenon; however, some major pathogeneses have been proposed, including inflammatory pathways, oxidative stress, and autonomic dysfunction. Genetic studies also showed that inflammatory pathways, beta-1 adrenoreceptor variants, G protein-coupled receptor kinase 5 gene variants, and non-coding single-nucleotide polymorphisms in the 4q25 chromosomal locus are involved in this phenomenon. Moreover, several predisposing factors lead to the development of POAF, consisting of pre-, intra-, and postoperative contributors. The main predisposing factors comprise age, prior history of major cardiovascular risk factors, and ischemia-reperfusion injury during surgery. The management of POAF is based on the usual therapies used for non-surgical AF, including medications for either rate control or rhythm control in hemodynamically unstable patients. The perioperative administration of β-blockers and some antiarrhythmic agents has been recommended in major international guidelines. In addition, upstream therapies consisting of colchicine, magnesium, statins, and antioxidants have attenuated the incidence of POAF; however, some uncomfortable side effects developed in large randomized trials. The use of anticoagulation has also resulted in less mortality in patients with POAF at higher risk of thromboembolic events. Despite these recommendations, the actual regimen for the prevention of POAF remains controversial. In this review, we highlight the pathogenesis, predisposing factors, and potential therapeutic options for the management of patients at risk for or with POAF following cardiac surgery.
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7
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Asfaw TN, Tyan L, Glukhov AV, Bondarenko VE. A compartmentalized mathematical model of mouse atrial myocytes. Am J Physiol Heart Circ Physiol 2020; 318:H485-H507. [PMID: 31951471 DOI: 10.1152/ajpheart.00460.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Various experimental mouse models are extensively used to research human diseases, including atrial fibrillation, the most common cardiac rhythm disorder. Despite this, there are no comprehensive mathematical models that describe the complex behavior of the action potential and [Ca2+]i transients in mouse atrial myocytes. Here, we develop a novel compartmentalized mathematical model of mouse atrial myocytes that combines the action potential, [Ca2+]i dynamics, and β-adrenergic signaling cascade for a subpopulation of right atrial myocytes with developed transverse-axial tubule system. The model consists of three compartments related to β-adrenergic signaling (caveolae, extracaveolae, and cytosol) and employs local control of Ca2+ release. It also simulates ionic mechanisms of action potential generation and describes atrial-specific Ca2+ handling as well as frequency dependences of the action potential and [Ca2+]i transients. The model showed that the T-type Ca2+ current significantly affects the later stage of the action potential, with little effect on [Ca2+]i transients. The block of the small-conductance Ca2+-activated K+ current leads to a prolongation of the action potential at high intracellular Ca2+. Simulation results obtained from the atrial model cells were compared with those from ventricular myocytes. The developed model represents a useful tool to study complex electrical properties in the mouse atria and could be applied to enhance the understanding of atrial physiology and arrhythmogenesis.NEW & NOTEWORTHY A new compartmentalized mathematical model of mouse right atrial myocytes was developed. The model simulated action potential and Ca2+ dynamics at baseline and after stimulation of the β-adrenergic signaling system. Simulations showed that the T-type Ca2+ current markedly prolonged the later stage of atrial action potential repolarization, with a minor effect on [Ca2+]i transients. The small-conductance Ca2+-activated K+ current block resulted in prolongation of the action potential only at the relatively high intracellular Ca2+.
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Affiliation(s)
- Tesfaye Negash Asfaw
- Department of Mathematics and Statistics, Georgia State University, Atlanta, Georgia
| | - Leonid Tyan
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin
| | - Alexey V Glukhov
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin
| | - Vladimir E Bondarenko
- Department of Mathematics and Statistics, Georgia State University, Atlanta, Georgia.,Neuroscience Institute, Georgia State University, Atlanta, Georgia
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8
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Mechanism of electrical remodeling of atrial myocytes and its influence on susceptibility to atrial fibrillation in diabetic rats. Life Sci 2019; 239:116903. [PMID: 31639397 DOI: 10.1016/j.lfs.2019.116903] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 09/14/2019] [Accepted: 09/22/2019] [Indexed: 02/06/2023]
Abstract
AIMS To explore the atrial electrical remodeling and the susceptibility of atrial fibrillation (AF) in diabetic rats. MATERIALS AND METHODS Zucker diabetic fatty (ZDF) rats were chosen as diabetic animal model, and age-matched non-diabetic littermate Zucker lean (ZL) rats as control. AF susceptibility was determined by electrophysiological examination. The current density of Ito, IKur and ICa-L were detected by whole-cell patch-clamp technique, and ion channel protein expression in atrial tissue and HL-1 cells treated with advanced glycation end products (AGE) was analyzed by western blotting. KEY FINDINGS Diabetic rats had significantly enlarged left atria and evenly thickened ventricular walls, hypertrophied cells and interstitial fibrosis in atrial myocardium, increased AF susceptibility, and prolonged AF duration after atrial burst stimulation. Compared with atrial myocytes isolated from ZL controls, atrial myocytes isolated from ZDF rats had prolonged action potential duration, decreased absolute value of resting membrane potential level and current densities of Ito, IKur and ICa-L. The ion channel protein (Kv4.3, Kv1.5 and Cav1.2) expression in atrium tissue of ZDF rats and HL-1 cells treated with high concentration AGE were significantly down-regulated, compared with controls. SIGNIFICANCE The atrial electrical remodeling induced by hyperglycemia contributed to the increased AF susceptibility in diabetic rats.
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9
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10
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Su Y, Li L, Zhao S, Yue Y, Yang S. The long noncoding RNA expression profiles of paroxysmal atrial fibrillation identified by microarray analysis. Gene 2018; 642:125-134. [DOI: 10.1016/j.gene.2017.11.025] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 10/28/2017] [Accepted: 11/08/2017] [Indexed: 12/11/2022]
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11
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Cheng H, Cannell MB, Hancox JC. Differential responses of rabbit ventricular and atrial transient outward current (I to) to the I to modulator NS5806. Physiol Rep 2017; 5:5/5/e13172. [PMID: 28270595 PMCID: PMC5350179 DOI: 10.14814/phy2.13172] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 01/26/2017] [Accepted: 01/27/2017] [Indexed: 02/06/2023] Open
Abstract
Transient outward potassium current (Ito) in the heart underlies phase 1 repolarization of cardiac action potentials and thereby affects excitation–contraction coupling. Small molecule activators of Ito may therefore offer novel treatments for cardiac dysfunction, including heart failure and atrial fibrillation. NS5806 has been identified as a prototypic activator of canine Ito. This study investigated, for the first time, actions of NS5806 on rabbit atrial and ventricular Ito. Whole cell patch‐clamp recordings of Ito and action potentials were made at physiological temperature from rabbit ventricular and atrial myocytes. 10 μmol/L NS5806 increased ventricular Ito with a leftward shift in Ito activation and accelerated restitution. At higher concentrations, stimulation of Ito was followed by inhibition. The EC50 for stimulation was 1.6 μmol/L and inhibition had an IC50 of 40.7 μmol/L. NS5806 only inhibited atrial Ito (IC50 of 18 μmol/L) and produced a modest leftward shifts in Ito activation and inactivation, without an effect on restitution. 10 μmol/L NS5806 shortened ventricular action potential duration (APD) at APD20‐APD90 but prolonged atrial APD. NS5806 also reduced atrial AP upstroke and amplitude, consistent with an additional atrio‐selective effect on Na+ channels. In contrast to NS5806, flecainide, which discriminates between Kv1.4 and 4.x channels, produced similar levels of inhibition of ventricular and atrial Ito. NS5806 discriminates between rabbit ventricular and atrial Ito, with mixed activator and inhibitor actions on the former and inhibitor actions against the later. NS5806 may be of significant value for pharmacological interrogation of regional differences in native cardiac Ito.
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Affiliation(s)
- Hongwei Cheng
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol, U.K
| | - Mark B Cannell
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol, U.K
| | - Jules C Hancox
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences Building, University Walk, Bristol, U.K
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12
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Ni H, Whittaker DG, Wang W, Giles WR, Narayan SM, Zhang H. Synergistic Anti-arrhythmic Effects in Human Atria with Combined Use of Sodium Blockers and Acacetin. Front Physiol 2017; 8:946. [PMID: 29218016 PMCID: PMC5703742 DOI: 10.3389/fphys.2017.00946] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 11/08/2017] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia. Developing effective and safe anti-AF drugs remains an unmet challenge. Simultaneous block of both atrial-specific ultra-rapid delayed rectifier potassium (K+) current (IKur) and the Na+ current (INa) has been hypothesized to be anti-AF, without inducing significant QT prolongation and ventricular side effects. However, the antiarrhythmic advantage of simultaneously blocking these two channels vs. individual block in the setting of AF-induced electrical remodeling remains to be documented. Furthermore, many IKur blockers such as acacetin and AVE0118, partially inhibit other K+ currents in the atria. Whether this multi-K+-block produces greater anti-AF effects compared with selective IKur-block has not been fully understood. The aim of this study was to use computer models to (i) assess the impact of multi-K+-block as exhibited by many IKur blokers, and (ii) evaluate the antiarrhythmic effect of blocking IKur and INa, either alone or in combination, on atrial and ventricular electrical excitation and recovery in the setting of AF-induced electrical-remodeling. Contemporary mathematical models of human atrial and ventricular cells were modified to incorporate dose-dependent actions of acacetin (a multichannel blocker primarily inhibiting IKur while less potently blocking Ito, IKr, and IKs). Rate- and atrial-selective inhibition of INa was also incorporated into the models. These single myocyte models were then incorporated into multicellular two-dimensional (2D) and three-dimensional (3D) anatomical models of the human atria. As expected, application of IKur blocker produced pronounced action potential duration (APD) prolongation in atrial myocytes. Furthermore, combined multiple K+-channel block that mimicked the effects of acacetin exhibited synergistic APD prolongations. Synergistically anti-AF effects following inhibition of INa and combined IKur/K+-channels were also observed. The attainable maximal AF-selectivity of INa inhibition was greatly augmented by blocking IKur or multiple K+-currents in the atrial myocytes. This enhanced anti-arrhythmic effects of combined block of Na+- and K+-channels were also seen in 2D and 3D simulations; specially, there was an enhanced efficacy in terminating re-entrant excitation waves, exerting improved antiarrhythmic effects in the human atria as compared to a single-channel block. However, in the human ventricular myocytes and tissue, cellular repolarization and computed QT intervals were modestly affected in the presence of actions of acacetin and INa blockers (either alone or in combination). In conclusion, this study demonstrates synergistic antiarrhythmic benefits of combined block of IKur and INa, as well as those of INa and combined multi K+-current block of acacetin, without significant alterations of ventricular repolarization and QT intervals. This approach may be a valuable strategy for the treatment of AF.
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Affiliation(s)
- Haibo Ni
- Biological Physics Group, University of Manchester, Manchester, United Kingdom.,Space Institute of Southern China, Shenzhen, China.,Key Laboratory of Medical Electrophysiology, Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease/Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China
| | - Dominic G Whittaker
- Biological Physics Group, University of Manchester, Manchester, United Kingdom
| | - Wei Wang
- Biological Physics Group, University of Manchester, Manchester, United Kingdom
| | - Wayne R Giles
- Faculties of Kinesiology and Medicine, University of Calgary, Calgary, AB, Canada
| | - Sanjiv M Narayan
- Department of Medicine, Stanford University School of Medicine, Stanford, CA, United States
| | - Henggui Zhang
- Biological Physics Group, University of Manchester, Manchester, United Kingdom.,Space Institute of Southern China, Shenzhen, China.,Key Laboratory of Medical Electrophysiology, Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Disease/Institute of Cardiovascular Research, Southwest Medical University, Luzhou, China.,School of Computer Science and Technology, Harbin Institute of Technology, Harbin, China
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13
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Ellinwood N, Dobrev D, Morotti S, Grandi E. In Silico Assessment of Efficacy and Safety of I Kur Inhibitors in Chronic Atrial Fibrillation: Role of Kinetics and State-Dependence of Drug Binding. Front Pharmacol 2017; 8:799. [PMID: 29163179 PMCID: PMC5681918 DOI: 10.3389/fphar.2017.00799] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 10/23/2017] [Indexed: 12/14/2022] Open
Abstract
Current pharmacological therapy against atrial fibrillation (AF), the most common cardiac arrhythmia, is limited by moderate efficacy and adverse side effects including ventricular proarrhythmia and organ toxicity. One way to circumvent the former is to target ion channels that are predominantly expressed in atria vs. ventricles, such as KV1.5, carrying the ultra-rapid delayed-rectifier K+ current (IKur). Recently, we used an in silico strategy to define optimal KV1.5-targeting drug characteristics, including kinetics and state-dependent binding, that maximize AF-selectivity in human atrial cardiomyocytes in normal sinus rhythm (nSR). However, because of evidence for IKur being strongly diminished in long-standing persistent (chronic) AF (cAF), the therapeutic potential of drugs targeting IKur may be limited in cAF patients. Here, we sought to simulate the efficacy (and safety) of IKur inhibitors in cAF conditions. To this end, we utilized sensitivity analysis of our human atrial cardiomyocyte model to assess the importance of IKur for atrial cardiomyocyte electrophysiological properties, simulated hundreds of theoretical drugs to reveal those exhibiting anti-AF selectivity, and compared the results obtained in cAF with those in nSR. We found that despite being downregulated, IKur contributes more prominently to action potential (AP) and effective refractory period (ERP) duration in cAF vs. nSR, with ideal drugs improving atrial electrophysiology (e.g., ERP prolongation) more in cAF than in nSR. Notably, the trajectory of the AP during cAF is such that more IKur is available during the more depolarized plateau potential. Furthermore, IKur block in cAF has less cardiotoxic effects (e.g., AP duration not exceeding nSR values) and can increase Ca2+ transient amplitude thereby enhancing atrial contractility. We propose that in silico strategies such as that presented here should be combined with in vitro and in vivo assays to validate model predictions and facilitate the ongoing search for novel agents against AF.
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Affiliation(s)
- Nicholas Ellinwood
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Dobromir Dobrev
- West German Heart and Vascular Center, Institute of Pharmacology, University Duisburg-Essen, Essen, Germany
| | - Stefano Morotti
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Eleonora Grandi
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
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14
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In-silico investigations of the functional impact of KCNA5 mutations on atrial mechanical dynamics. J Mol Cell Cardiol 2017; 111:86-95. [DOI: 10.1016/j.yjmcc.2017.08.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 07/19/2017] [Accepted: 08/04/2017] [Indexed: 12/20/2022]
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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: 51] [Impact Index Per Article: 7.3] [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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Ellinwood N, Dobrev D, Morotti S, Grandi E. Revealing kinetics and state-dependent binding properties of I Kur-targeting drugs that maximize atrial fibrillation selectivity. CHAOS (WOODBURY, N.Y.) 2017; 27:093918. [PMID: 28964116 PMCID: PMC5573366 DOI: 10.1063/1.5000226] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 07/06/2017] [Indexed: 06/07/2023]
Abstract
The KV1.5 potassium channel, which underlies the ultra-rapid delayed-rectifier current (IKur) and is predominantly expressed in atria vs. ventricles, has emerged as a promising target to treat atrial fibrillation (AF). However, while numerous KV1.5-selective compounds have been screened, characterized, and tested in various animal models of AF, evidence of antiarrhythmic efficacy in humans is still lacking. Moreover, current guidelines for pre-clinical assessment of candidate drugs heavily rely on steady-state concentration-response curves or IC50 values, which can overlook adverse cardiotoxic effects. We sought to investigate the effects of kinetics and state-dependent binding of IKur-targeting drugs on atrial electrophysiology in silico and reveal the ideal properties of IKur blockers that maximize anti-AF efficacy and minimize pro-arrhythmic risk. To this aim, we developed a new Markov model of IKur that describes KV1.5 gating based on experimental voltage-clamp data in atrial myocytes from patient right-atrial samples in normal sinus rhythm. We extended the IKur formulation to account for state-specificity and kinetics of KV1.5-drug interactions and incorporated it into our human atrial cell model. We simulated 1- and 3-Hz pacing protocols in drug-free conditions and with a [drug] equal to the IC50 value. The effects of binding and unbinding kinetics were determined by examining permutations of the forward (kon) and reverse (koff) binding rates to the closed, open, and inactivated states of the KV1.5 channel. We identified a subset of ideal drugs exhibiting anti-AF electrophysiological parameter changes at fast pacing rates (effective refractory period prolongation), while having little effect on normal sinus rhythm (limited action potential prolongation). Our results highlight that accurately accounting for channel interactions with drugs, including kinetics and state-dependent binding, is critical for developing safer and more effective pharmacological anti-AF options.
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Affiliation(s)
- Nicholas Ellinwood
- Department of Pharmacology, University of California Davis, Davis, California 95616, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | - Stefano Morotti
- Department of Pharmacology, University of California Davis, Davis, California 95616, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California 95616, USA
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17
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Heijman J, Ghezelbash S, Wehrens XHT, Dobrev D. Serine/Threonine Phosphatases in Atrial Fibrillation. J Mol Cell Cardiol 2017; 103:110-120. [PMID: 28077320 DOI: 10.1016/j.yjmcc.2016.12.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 12/15/2016] [Accepted: 12/20/2016] [Indexed: 12/19/2022]
Abstract
Serine/threonine protein phosphatases control dephosphorylation of numerous cardiac proteins, including a variety of ion channels and calcium-handling proteins, thereby providing precise post-translational regulation of cardiac electrophysiology and function. Accordingly, dysfunction of this regulation can contribute to the initiation, maintenance and progression of cardiac arrhythmias. Atrial fibrillation (AF) is the most common heart rhythm disorder and is characterized by electrical, autonomic, calcium-handling, contractile, and structural remodeling, which include, among other things, changes in the phosphorylation status of a wide range of proteins. Here, we review AF-associated alterations in the phosphorylation of atrial ion channels, calcium-handling and contractile proteins, and their role in AF-pathophysiology. We highlight the mechanisms controlling the phosphorylation of these proteins and focus on the role of altered dephosphorylation via local type-1, type-2A and type-2B phosphatases (PP1, PP2A, and PP2B, also known as calcineurin, respectively). Finally, we discuss the challenges for phosphatase research, potential therapeutic significance of altered phosphatase-mediated protein dephosphorylation in AF, as well as future directions.
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Affiliation(s)
- Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Faculty of Health, Medicine, and Life Sciences, Maastricht University, Maastricht, The Netherlands
| | - Shokoufeh Ghezelbash
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Department of Molecular Physiology and Biophysics, Department of Medicine (Cardiology), Pediatrics, Baylor College of Medicine, Houston, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany.
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18
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Abstract
Postoperative atrial fibrillation (PoAF), a common complication of cardiac surgery, contributes significantly to morbidity, mortality, and increasing healthcare costs. Despite advances in surgical and medical management, the overall incidence of PoAF has not changed significantly, partly because of the limited understanding of mechanisms underlying acute surgery-related factors, such as myocardial injury, inflammation, sympathetic activation, and oxidative stress, which play an important role in the initiation of PoAF, whereas a preexisting atrial substrate appears to be more important in the maintenance of this dysrhythmia. Thus, in a majority of patients, PoAF becomes a manifestation of an underlying arrhythmogenic substrate that is unmasked after acute surgical stress. As such, the ability to identify which patients have this proarrhythmic substrate and are, therefore, at high risk for developing AF postoperatively, is important for the improved selection for prophylactic interventions, closer monitoring for complications, and establishing the probability of AF in the long term. This review highlights the role of the underlying substrate in promoting PoAF, proposed mechanisms, and the potential role of serum biomarkers to identify patients at risk for PoAF.
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19
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Grandi E, Maleckar MM. Anti-arrhythmic strategies for atrial fibrillation: The role of computational modeling in discovery, development, and optimization. Pharmacol Ther 2016; 168:126-142. [PMID: 27612549 DOI: 10.1016/j.pharmthera.2016.09.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Atrial fibrillation (AF), the most common cardiac arrhythmia, is associated with increased risk of cerebrovascular stroke, and with several other pathologies, including heart failure. Current therapies for AF are targeted at reducing risk of stroke (anticoagulation) and tachycardia-induced cardiomyopathy (rate or rhythm control). Rate control, typically achieved by atrioventricular nodal blocking drugs, is often insufficient to alleviate symptoms. Rhythm control approaches include antiarrhythmic drugs, electrical cardioversion, and ablation strategies. Here, we offer several examples of how computational modeling can provide a quantitative framework for integrating multiscale data to: (a) gain insight into multiscale mechanisms of AF; (b) identify and test pharmacological and electrical therapy and interventions; and (c) support clinical decisions. We review how modeling approaches have evolved and contributed to the research pipeline and preclinical development and discuss future directions and challenges in the field.
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Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, USA.
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20
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Sirish P, Li N, Timofeyev V, Zhang XD, Wang L, Yang J, Lee KSS, Bettaieb A, Ma SM, Lee JH, Su D, Lau VC, Myers RE, Lieu DK, López JE, Young JN, Yamoah EN, Haj F, Ripplinger CM, Hammock BD, Chiamvimonvat N. Molecular Mechanisms and New Treatment Paradigm for Atrial Fibrillation. Circ Arrhythm Electrophysiol 2016; 9:CIRCEP.115.003721. [PMID: 27162031 DOI: 10.1161/circep.115.003721] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 04/01/2016] [Indexed: 12/22/2022]
Abstract
BACKGROUND Atrial fibrillation represents the most common arrhythmia leading to increased morbidity and mortality, yet, current treatment strategies have proven inadequate. Conventional treatment with antiarrhythmic drugs carries a high risk for proarrhythmias. The soluble epoxide hydrolase enzyme catalyzes the hydrolysis of anti-inflammatory epoxy fatty acids, including epoxyeicosatrienoic acids from arachidonic acid to the corresponding proinflammatory diols. Therefore, the goal of the study is to directly test the hypotheses that inhibition of the soluble epoxide hydrolase enzyme can result in an increase in the levels of epoxyeicosatrienoic acids, leading to the attenuation of atrial structural and electric remodeling and the prevention of atrial fibrillation. METHODS AND RESULTS For the first time, we report findings that inhibition of soluble epoxide hydrolase reduces inflammation, oxidative stress, atrial structural, and electric remodeling. Treatment with soluble epoxide hydrolase inhibitor significantly reduces the activation of key inflammatory signaling molecules, including the transcription factor nuclear factor κ-light-chain-enhancer, mitogen-activated protein kinase, and transforming growth factor-β. CONCLUSIONS This study provides insights into the underlying molecular mechanisms leading to atrial fibrillation by inflammation and represents a paradigm shift from conventional antiarrhythmic drugs, which block downstream events to a novel upstream therapeutic target by counteracting the inflammatory processes in atrial fibrillation.
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Affiliation(s)
- Padmini Sirish
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Ning Li
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Valeriy Timofeyev
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Xiao-Dong Zhang
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Lianguo Wang
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Jun Yang
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Kin Sing Stephen Lee
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Ahmed Bettaieb
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Sin Mei Ma
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Jeong Han Lee
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Demetria Su
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Victor C Lau
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Richard E Myers
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Deborah K Lieu
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Javier E López
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - J Nilas Young
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Ebenezer N Yamoah
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Fawaz Haj
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Crystal M Ripplinger
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Bruce D Hammock
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.)
| | - Nipavan Chiamvimonvat
- From the Division of Cardiovascular Medicine (P.S., N.L., V.T., X.-D.Z., S.M.M., D.S., V.C.L., R.E.M., D.K.L., J.E.L., N.C.), Department of Pharmacology (L.W., C.M.R.), Department of Entomology and Nematology, Comprehensive Cancer Center (J.Y., K.S.S.L., B.D.H.), Department of Nutrition (A.B., F.H.), and Department of Cardiothoracic Surgery (J.N.Y.), University of California, Davis; Department of Physiology and Cell Biology, University of Nevada, Reno (J.H.L., E.N.Y.); and Department of Veterans Affairs, Northern California Health Care System, Mather (N.C.).
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Wasson S, Reddy HK, Dohrmann ML. Current Perspectives of Electrical Remodeling and Its Therapeutic Implications. J Cardiovasc Pharmacol Ther 2016; 9:129-44. [PMID: 15309249 DOI: 10.1177/107424840400900208] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Electrical remodeling involves alterations in the electrophysiologic milieu of myocardium in various disease states, such as ventricular hypertrophy, heart failure, atrial tachyarrhythmias, myocardial ischemia, and infarction that are associated with cardiac arrhythmias. Although research in this area dates back to early part of the 19th century, we still lack the exact knowledge of ionic remodeling, the role of various genes and channel proteins, and their relevance for the newer antiarrhythmic therapies. Structural remodeling may also have an impact on the electrical remodeling process, although differences in both structural and electrical remodeling are associated with different disease states. Various electrophysiologic, cellular, and structural alterations, including anisotropic conduction, increased intracellular calcium levels, and gap junction remodeling predispose to increased dispersion of action potential duration and refractoriness. This constitutes a favorable substrate for early and late afterdepolarizations and reentrant arrhythmias. Studying the role of ionic remodeling in the initiation and propagation of cardiac arrhythmias has significant relevance for developing newer antiarrhythmic therapies, for identifying patients at risk of developing fatal arrhythmias, and for implementing effective preventive measures. Further research is required to understand the specific effects of individual ion channel remodeling, to understand the signal transduction mechanisms, and to address whether detrimental effects of electrical remodeling can be altered.
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Affiliation(s)
- Sanjeev Wasson
- Division of Cardiology, University of Missouri Hospital, Columbia, Missouri 65212, USA
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Abstract
Optimal cardiac function depends on proper timing of excitation and contraction in various regions of the heart, as well as on appropriate heart rate. This is accomplished via specialized electrical properties of various components of the system, including the sinoatrial node, atria, atrioventricular node, His-Purkinje system, and ventricles. Here we review the major regionally determined electrical properties of these cardiac regions and present the available data regarding the molecular and ionic bases of regional cardiac function and dysfunction. Understanding these differences is of fundamental importance for the investigation of arrhythmia mechanisms and pharmacotherapy.
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Affiliation(s)
- Daniel C Bartos
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - Crystal M Ripplinger
- Department of Pharmacology, University of California Davis, Davis, California, USA
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23
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Vilches JM, Franco D, Aránega AE. Contribution of miRNAs to ion-channel remodelling in atrial fibrillation. World J Hypertens 2015; 5:6-13. [DOI: 10.5494/wjh.v5.i1.6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 11/12/2014] [Accepted: 12/10/2014] [Indexed: 02/06/2023] Open
Abstract
Atrial fibrillation (AF) is the most commonly encountered clinical arrhythmia associated with pronounced mortality and morbidity, which are related to palpitations, fainting, congestive heart failure, and stroke. Prolonged episodes of AF promote AF persistence mainly due to electrical remodelling that alters ion-channel expression and/or function. MicroRNAs (miRNAs), a new class of non-coding mRNAs of around 22 nucleotides in length, have recently emerged as one of the key players in the gene-expression regulatory networks. The potential roles of miRNAs in controlling AF have recently been investigated. Several recent studies have provided promising results for a better understanding of the molecular mechanisms of AF. In this review, we summarize the mechanism of miRNAs as regulators of ion-channel gene expression and their role in causing AF through electrical remodelling.
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Schmitt N, Grunnet M, Olesen SP. Cardiac potassium channel subtypes: new roles in repolarization and arrhythmia. Physiol Rev 2014; 94:609-53. [PMID: 24692356 DOI: 10.1152/physrev.00022.2013] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
About 10 distinct potassium channels in the heart are involved in shaping the action potential. Some of the K+ channels are primarily responsible for early repolarization, whereas others drive late repolarization and still others are open throughout the cardiac cycle. Three main K+ channels drive the late repolarization of the ventricle with some redundancy, and in atria this repolarization reserve is supplemented by the fairly atrial-specific KV1.5, Kir3, KCa, and K2P channels. The role of the latter two subtypes in atria is currently being clarified, and several findings indicate that they could constitute targets for new pharmacological treatment of atrial fibrillation. The interplay between the different K+ channel subtypes in both atria and ventricle is dynamic, and a significant up- and downregulation occurs in disease states such as atrial fibrillation or heart failure. The underlying posttranscriptional and posttranslational remodeling of the individual K+ channels changes their activity and significance relative to each other, and they must be viewed together to understand their role in keeping a stable heart rhythm, also under menacing conditions like attacks of reentry arrhythmia.
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Colman MA, Aslanidi OV, Kharche S, Boyett MR, Garratt C, Hancox JC, Zhang H. Pro-arrhythmogenic effects of atrial fibrillation-induced electrical remodelling: insights from the three-dimensional virtual human atria. J Physiol 2013; 591:4249-72. [PMID: 23732649 PMCID: PMC3779115 DOI: 10.1113/jphysiol.2013.254987] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Chronic atrial fibrillation (AF) is associated with structural and electrical remodelling in the atria, which are associated with a high recurrence of AF. Through biophysically detailed computer modelling, this study investigated mechanisms by which AF-induced electrical remodelling promotes and perpetuates AF. A family of Courtemanche–Ramirez–Nattel variant models of human atrial cell action potentials (APs), taking into account of intrinsic atrial electrophysiological properties, was modified to incorporate various experimental data sets on AF-induced changes of major ionic channel currents (ICaL, IKur, Ito, IK1, IKs, INaCa) and on intracellular Ca2+ handling. The single cell models for control and AF-remodelled conditions were incorporated into multicellular three-dimensional (3D) atrial tissue models. Effects of the AF-induced electrical remodelling were quantified as the changes of AP profile, AP duration (APD) and its dispersion across the atria, and the vulnerability of atrial tissue to the initiation of re-entry. The dynamic behaviour of re-entrant excitation waves in the 3D models was characterised. In our simulations, AF-induced electrical remodelling abbreviated atrial APD non-uniformly across the atria; this resulted in relatively short APDs co-existing with marked regional differences in the APD at junctions of the crista terminalis/pectinate muscle, pulmonary veins/left atrium. As a result, the measured tissue vulnerability to re-entry initiation at these tissue junctions was increased. The AF-induced electrical remodelling also stabilized and accelerated re-entrant excitation waves, leading to rapid and sustained re-entry. Under the AF-remodelled condition, re-entrant scroll waves in the 3D model degenerated into persistent and erratic wavelets, leading to fibrillation. In conclusion, realistic 3D atrial tissue models indicate that AF-induced electrical remodelling produces regionally heterogeneous and shortened APD; these respectively facilitate initiation and maintenance of re-entrant excitation waves.
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Affiliation(s)
- Michael A Colman
- Professor H. Zhang: School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL, UK.
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26
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Cardiac ion channels and mechanisms for protection against atrial fibrillation. Rev Physiol Biochem Pharmacol 2013; 162:1-58. [PMID: 21987061 DOI: 10.1007/112_2011_3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Atrial fibrillation (AF) is recognised as the most common sustained cardiac arrhythmia in clinical practice. Ongoing drug development is aiming at obtaining atrial specific effects in order to prevent pro-arrhythmic, devastating ventricular effects. In principle, this is possible due to a different ion channel composition in the atria and ventricles. The present text will review the aetiology of arrhythmias with focus on AF and include a description of cardiac ion channels. Channels that constitute potentially atria-selective targets will be described in details. Specific focus is addressed to the recent discovery that Ca(2+)-activated small conductance K(+) channels (SK channels) are important for the repolarisation of atrial action potentials. Finally, an overview of current pharmacological treatment of AF is included.
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Chang CJ, Chen YC, Lin YK, Huang JH, Chen SA, Chen YJ. Rivaroxaban modulates electrical and mechanical characteristics of left atrium. J Biomed Sci 2013; 20:17. [PMID: 23497194 PMCID: PMC3608950 DOI: 10.1186/1423-0127-20-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Accepted: 03/11/2013] [Indexed: 11/25/2022] Open
Abstract
Background Rivaroxaban reduces stroke in patients with atrial fibrillation (AF). Left atrium (LA) plays a critical role in the pathophysiology of AF. However, the electromechanical effects of rivaroxaban on LA are not clear. Results Conventional microelectrodes and a whole-cell patch-clamp were used to record the action potentials (APs) and ionic currents in rabbit LA preparations and isolated single LA cardiomyocytes before and after the administration of rivaroxaban. Rivaroxaban (10, 30, 100, and 300 nM) concentration-dependently reduced LA (n = 7) AP durations at 90% repolarization (APD90) from 76 ± 2 to 79 ± 3, 67 ± 4 (P < 0.05, vs. control), 59 ± 5, (P < 0.01, vs. control), and 56 ± 4 ms (P < 0.005, vs. control), respectively. Rivaroxaban (10, 30, 100, and 300 nM) concentration-dependently increased the LA (n = 7) diastolic tension by 351 ± 69 (P < 0.05, vs. control), 563 ± 136 (P < 0.05, vs. control), 582 ± 119 (P < 0.05, vs. control), and 603 ± 108 mg (P < 0.005, vs. control), respectively, but did not change LA contractility. In the presence of L-NAME (100 μM) and indomethacin (10 μM), additional rivaroxaban (300 nM) treatment did not significantly further increase the LA (n = 7) diastolic tension, but shortened the APD90 from 73 ± 2 to 60 ± 6 ms (P < 0.05, vs. control). Rivaroxaban (100 nM) increased the L-type calcium current and ultra-rapid delayed rectifier potassium current, but did not change the transient outward potassium current in isolated LA cardiomyocytes. Conclusions Rivaroxaban modulates LA electrical and mechanical characteristics with direct ionic current effects.
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Affiliation(s)
- Chien-Jung Chang
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, and Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, 111 Hsin-Lung Road Sec. 3, Taipei 116, Taiwan
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Ambrosi CM, Yamada KA, Nerbonne JM, Efimov IR. Gender differences in electrophysiological gene expression in failing and non-failing human hearts. PLoS One 2013; 8:e54635. [PMID: 23355885 PMCID: PMC3552854 DOI: 10.1371/journal.pone.0054635] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 12/13/2012] [Indexed: 12/19/2022] Open
Abstract
The increasing availability of human cardiac tissues for study are critically important in increasing our understanding of the impact of gender, age, and other parameters, such as medications and cardiac disease, on arrhythmia susceptibility. In this study, we aimed to compare the mRNA expression of 89 ion channel subunits, calcium handling proteins, and transcription factors important in cardiac conduction and arrhythmogenesis in the left atria (LA) and ventricles (LV) of failing and nonfailing human hearts of both genders. Total RNA samples, prepared from failing male (n = 9) and female (n = 7), and from nonfailing male (n = 9) and female (n = 9) hearts, were probed using custom-designed Taqman gene arrays. Analyses were performed to explore the relationships between gender, failure state, and chamber expression. Hierarchical cluster analysis revealed chamber specific expression patterns, but failed to identify disease- or gender-dependent clustering. Gender-specific analysis showed lower expression levels in transcripts encoding for Kv4.3, KChIP2, Kv1.5, and Kir3.1 in the failing female as compared with the male LA. Analysis of LV transcripts, however, did not reveal significant differences based on gender. Overall, our data highlight the differential expression and transcriptional remodeling of ion channel subunits in the human heart as a function of gender and cardiac disease. Furthermore, the availability of such data sets will allow for the development of disease-, gender-, and, most importantly, patient-specific cardiac models, with the ability to utilize such information as mRNA expression to predict cardiac phenotype.
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Affiliation(s)
- Christina M. Ambrosi
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
| | - Kathryn A. Yamada
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Jeanne M. Nerbonne
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Igor R. Efimov
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, United States of America
- * E-mail:
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Heijman J, Voigt N, Dobrev D. New directions in antiarrhythmic drug therapy for atrial fibrillation. Future Cardiol 2013; 9:71-88. [DOI: 10.2217/fca.12.78] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia and has a significant impact on morbidity and mortality. Current antiarrhythmic drugs for AF suffer from limited safety and efficacy, probably because they were not designed based on specific pathological mechanisms. Recent research has provided important insights into the mechanisms contributing to AF and highlighted several potential novel antiarrhythmic strategies. In this review, we highlight the main pathological mechanisms of AF, discuss traditional and novel aspects of atrial antiarrhythmic drugs in relation to these pathological mechanisms, and present potential novel therapeutic approaches including structure-based modulation of atrial-specific cardiac ion channels, restoring abnormal Ca2+ handling in AF and targeting atrial remodeling.
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Affiliation(s)
- Jordi Heijman
- Institute of Pharmacology, Medical Faculty Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany
| | - Niels Voigt
- Institute of Pharmacology, Medical Faculty Essen, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany
- Division of Experimental Cardiology, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
| | - Dobromir Dobrev
- DZHK (German Centre for Cardiovascular Research), Partner Site Heidelberg/Mannheim, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
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Cheng CC, Weerateerangkul P, Lu YY, Chen YC, Lin YK, Chen SA, Chen YJ. Apelin regulates the electrophysiological characteristics of atrial myocytes. Eur J Clin Invest 2013; 43:34-40. [PMID: 23106642 DOI: 10.1111/eci.12012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND Apelin, a potential agent for treating heart failure, has various ionic effects on ventricular myocytes. However, the effects of apelin on the atrium are not clear. The purpose of this study was to investigate the acute effects of apelin on the electrophysiological characteristics of atrial myocytes. METHOD Whole-cell patch-clamp techniques were used to investigate the action potential (AP) and ionic currents in isolated rabbit left atrial (LA) myocytes before and after the administration of apelin. RESULT Apelin reduced LA AP duration measured at 90%, 50% and 20% repolarization of the amplitude by 11 ± 3%, 24 ± 5%, 30 ± 7% at 1 nM (n = 11), and by 14 ± 4%, 36 ± 6% and 45 ± 5% at 10 nM (n = 11), but not at 0·1 nM. Apeline (0·1, 1, 10 nM) did not change the amplitude, or resting membrane potential in LA myocytes. Apelin (1 nM) increased sodium currents, ultra-rapid potassium currents and the reverse mode of sodium-calcium exchanger currents, but decreased late sodium currents and L-type calcium currents and did not change transient outward currents or inward rectifier potassium currents in LA myocytes. CONCLUSIONS Apelin significantly changed the atrial electrophysiology with a shortening of AP duration, which may be caused by its effects on multiple ionic currents.
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Heijman J, Dobrev D. Systems approaches to post-operative atrial fibrillation - do they help us to better understand the ionic basis of the arrhythmogenic substrate? J Mol Cell Cardiol 2012; 53:320-2. [PMID: 22742961 DOI: 10.1016/j.yjmcc.2012.06.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 06/11/2012] [Accepted: 06/14/2012] [Indexed: 12/19/2022]
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Grandi E, Workman AJ, Pandit SV. Altered Excitation-Contraction Coupling in Human Chronic Atrial Fibrillation. J Atr Fibrillation 2012; 4:495. [PMID: 28496736 DOI: 10.4022/jafib.495] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Revised: 02/10/2012] [Accepted: 03/19/2012] [Indexed: 12/19/2022]
Abstract
This review focuses on the (mal)adaptive processes in atrial excitation-contraction coupling occurring in patients with chronic atrial fibrillation. Cellular remodeling includes shortening of the atrial action potential duration and effective refractory period, depressed intracellular Ca2+ transient, and reduced myocyte contractility. Here we summarize the current knowledge of the ionic bases underlying these changes. Understanding the molecular mechanisms of excitation-contraction-coupling remodeling in the fibrillating human atria is important to identify new potential targets for AF therapy.
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Affiliation(s)
- Eleonora Grandi
- Department of Pharmacology, University of California at Davis, Davis, CA, USA
| | - Antony J Workman
- Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK
| | - Sandeep V Pandit
- Center for Arrhythmia Research, University of Michigan, Ann Arbor, MI, USA
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Maesen B, Nijs J, Maessen J, Allessie M, Schotten U. Post-operative atrial fibrillation: a maze of mechanisms. Europace 2011; 14:159-74. [PMID: 21821851 PMCID: PMC3262403 DOI: 10.1093/europace/eur208] [Citation(s) in RCA: 293] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Post-operative atrial fibrillation (POAF) is one of the most frequent complications of cardiac surgery and an important predictor of patient morbidity as well as of prolonged hospitalization. It significantly increases costs for hospitalization. Insights into the pathophysiological factors causing POAF have been provided by both experimental and clinical investigations and show that POAF is ‘multi-factorial’. Facilitating factors in the mechanism of the arrhythmia can be classified as acute factors caused by the surgical intervention and chronic factors related to structural heart disease and ageing of the heart. Furthermore, some proarrhythmic mechanisms specifically occur in the setting of POAF. For example, inflammation and beta-adrenergic activation have been shown to play a prominent role in POAF, while these mechanisms are less important in non-surgical AF. More recently, it has been shown that atrial fibrosis and the presence of an electrophysiological substrate capable of maintaining AF also promote the arrhythmia, indicating that POAF has some proarrhythmic mechanisms in common with other forms of AF. The clinical setting of POAF offers numerous opportunities to study its mechanisms. During cardiac surgery, biopsies can be taken and detailed electrophysiological measurements can be performed. Furthermore, the specific time course of POAF, with the delayed onset and the transient character of the arrhythmia, also provides important insight into its mechanisms. This review discusses the mechanistic interaction between predisposing factors and the electrophysiological mechanisms resulting in POAF and their therapeutic implications.
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Affiliation(s)
- Bart Maesen
- Department of Cardiothoracic Surgery, University Hospital of Maastricht, PO Box 5800, 6202 AZ Maastricht, The Netherlands
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Schotten U, Verheule S, Kirchhof P, Goette A. Pathophysiological mechanisms of atrial fibrillation: a translational appraisal. Physiol Rev 2011; 91:265-325. [PMID: 21248168 DOI: 10.1152/physrev.00031.2009] [Citation(s) in RCA: 863] [Impact Index Per Article: 66.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Atrial fibrillation (AF) is an arrhythmia that can occur as the result of numerous different pathophysiological processes in the atria. Some aspects of the morphological and electrophysiological alterations promoting AF have been studied extensively in animal models. Atrial tachycardia or AF itself shortens atrial refractoriness and causes loss of atrial contractility. Aging, neurohumoral activation, and chronic atrial stretch due to structural heart disease activate a variety of signaling pathways leading to histological changes in the atria including myocyte hypertrophy, fibroblast proliferation, and complex alterations of the extracellular matrix including tissue fibrosis. These changes in electrical, contractile, and structural properties of the atria have been called "atrial remodeling." The resulting electrophysiological substrate is characterized by shortening of atrial refractoriness and reentrant wavelength or by local conduction heterogeneities caused by disruption of electrical interconnections between muscle bundles. Under these conditions, ectopic activity originating from the pulmonary veins or other sites is more likely to occur and to trigger longer episodes of AF. Many of these alterations also occur in patients with or at risk for AF, although the direct demonstration of these mechanisms is sometimes challenging. The diversity of etiological factors and electrophysiological mechanisms promoting AF in humans hampers the development of more effective therapy of AF. This review aims to give a translational overview on the biological basis of atrial remodeling and the proarrhythmic mechanisms involved in the fibrillation process. We pay attention to translation of pathophysiological insights gained from in vitro experiments and animal models to patients. Also, suggestions for future research objectives and therapeutical implications are discussed.
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Affiliation(s)
- Ulrich Schotten
- Department of Physiology, University Maastricht, Maastricht, The Netherlands.
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Ravens U, Wettwer E. Ultra-rapid delayed rectifier channels: molecular basis and therapeutic implications. Cardiovasc Res 2010; 89:776-85. [DOI: 10.1093/cvr/cvq398] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
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Discrepant electrophysiological characteristics and calcium homeostasis of left atrial anterior and posterior myocytes. Basic Res Cardiol 2010; 106:65-74. [PMID: 21072524 DOI: 10.1007/s00395-010-0132-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 10/13/2010] [Accepted: 10/22/2010] [Indexed: 10/18/2022]
Abstract
The left atrial (LA) posterior wall has been demonstrated to have regional electrophysiological differences with a higher arrhythmogenic potential leading to atrial fibrillation (AF). However, the ionic characteristics and calcium regulation in the LA anterior and posterior myocytes have not been fully elucidated. The purpose of this study was to investigate the electrical characteristics of the LA anterior and posterior myocytes. Whole-cell patch-clamp techniques and the indo-1 fluorimetric ratio technique were used to investigate the characteristics of the ionic currents, action potentials, and intracellular calcium in single isolated rabbit myocytes in the LA anterior and posterior walls. The expression of the Na(+)-Ca(2+) exchanger (NCX) and ryanodine receptor (RyR) were evaluated by a Western blot. The LA posterior myocytes (n = 15) had a higher incidence (53 vs. 19%, P < 0.05) of delayed afterdepolarizations than the LA anterior myocytes (n = 16). The LA posterior myocytes had larger sodium currents and late sodium currents, but smaller inward rectifier potassium currents than the LA anterior myocytes. The LA posterior myocytes had larger intracellular Ca(2+) transient and sarcoplasmic reticulum Ca(2+) contents as compared with the LA anterior myocytes. However, the NCX currents in the LA posterior myocytes were smaller than those in the LA anterior myocytes. The LA posterior myocytes had a smaller protein expression of NCX, but a larger protein expression of RyR than the LA anterior myocytes. In conclusion, LA posterior myocytes contain a high arrhythmogenic potential and distinctive electrophysiological characteristics, which may contribute to the pathophysiology of AF.
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Niwa N, Nerbonne JM. Molecular determinants of cardiac transient outward potassium current (I(to)) expression and regulation. J Mol Cell Cardiol 2009; 48:12-25. [PMID: 19619557 DOI: 10.1016/j.yjmcc.2009.07.013] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 06/25/2009] [Accepted: 07/10/2009] [Indexed: 12/21/2022]
Abstract
Rapidly activating and inactivating cardiac transient outward K(+) currents, I(to), are expressed in most mammalian cardiomyocytes, and contribute importantly to the early phase of action potential repolarization and to plateau potentials. The rapidly recovering (I(t)(o,f)) and slowly recovering (I(t)(o,s)) components are differentially expressed in the myocardium, contributing to regional heterogeneities in action potential waveforms. Consistent with the marked differences in biophysical properties, distinct pore-forming (alpha) subunits underlie the two I(t)(o) components: Kv4.3/Kv4.2 subunits encode I(t)(o,f), whereas Kv1.4 encodes I(t)(o,s), channels. It has also become increasingly clear that cardiac I(t)(o) channels function as components of macromolecular protein complexes, comprising (four) Kvalpha subunits and a variety of accessory subunits and regulatory proteins that influence channel expression, biophysical properties and interactions with the actin cytoskeleton, and contribute to the generation of normal cardiac rhythms. Derangements in the expression or the regulation of I(t)(o) channels in inherited or acquired cardiac diseases would be expected to increase the risk of potentially life-threatening cardiac arrhythmias. Indeed, a recently identified Brugada syndrome mutation in KCNE3 (MiRP2) has been suggested to result in increased I(t)(o,f) densities. Continued focus in this area seems certain to provide new and fundamentally important insights into the molecular determinants of functional I(t)(o) channels and into the molecular mechanisms involved in the dynamic regulation of I(t)(o) channel functioning in the normal and diseased myocardium.
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Affiliation(s)
- Noriko Niwa
- Department of Developmental Biology, Washington University School of Medicine, 660 South Euclid Avenue, Box 8103, St. Louis, MO 63110-1093, USA
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Noguchi C, Yang J, Sakamoto K, Maeda R, Takahashi K, Takasugi H, Ono T, Murakawa M, Kimura J. Inhibitory effects of isoliquiritigenin and licorice extract on voltage-dependent K(+) currents in H9c2 cells. J Pharmacol Sci 2009; 108:439-45. [PMID: 19098391 DOI: 10.1254/jphs.08227fp] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The effect of isoliquiritigenin (ISL), a component of licorice, on the voltage-dependent, ultra-rapidly activating delayed-rectifier K(+) current (IKur) was examined in H9c2 cells, a cell-line derived from rat cardiac myoblasts. IKur was recorded using the whole-cell patch clamp method with a pipette solution containing 140 mM K(+). Depolarizing voltage pulses of 200-ms duration were given with 10-mV steps every 10 s from -40 mV holding potential. ISL inhibited IKur in a concentration-dependent manner. The median inhibitory concentration (IC(50)) of ISL was approximately 0.11 microM and the Hill coefficient was 0.71. Using CHO cells expressing Kv1.5 IKur channels, ISL also inhibited Kv1.5 IKur, but less potently than the IKur current in H9c2 cells. Furthermore, in H9c2 cells, the licorice extract itself inhibited IKur in a manner similar to ISL. We conclude that ISL, one component of licorice, is a potent inhibitor of K(+) channels, which specifically in H9c2 cells could be Kv2.1, and that this inhibition may be involved in various pharmacological effects of licorice.
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Affiliation(s)
- Chisato Noguchi
- Department of Anesthesiology, Fukushima Medical University, School of Medicine, Japan
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Mathematical simulations of ligand-gated and cell-type specific effects on the action potential of human atrium. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2009; 98:161-70. [PMID: 19186188 DOI: 10.1016/j.pbiomolbio.2009.01.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In the mammalian heart, myocytes and fibroblasts can communicate via gap junction, or connexin-mediated current flow. Some of the effects of this electrotonic coupling on the action potential waveform of the human ventricular myocyte have been analyzed in detail. The present study employs a recently developed mathematical model of the human atrial myocyte to investigate the consequences of this heterogeneous cell-cell interaction on the action potential of the human atrium. Two independent physiological processes which alter the physiology of the human atrium have been studied. i) The effects of the autonomic transmitter acetylcholine on the atrial action potential have been investigated by inclusion of a time-independent, acetylcholine-activated K(+) current in this mathematical model of the atrial myocyte. ii) A non-selective cation current which is activated by natriuretic peptides has been incorporated into a previously published mathematical model of the cardiac fibroblast. These results identify subtle effects of acetylcholine, which arise from the nonlinear interactions between ionic currents in the human atrial myocyte. They also illustrate marked alterations in the action potential waveform arising from fibroblast-myocyte source-sink principles when the natriuretic peptide-mediated cation conductance is activated. Additional calculations also illustrate the effects of simultaneous activation of both of these cell-type specific conductances within the atrial myocardium. This study provides a basis for beginning to assess the utility of mathematical modeling in understanding detailed cell-cell interactions within the complex paracrine environment of the human atrial myocardium.
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Characterization of human cardiac Kv1.5 inhibition by the novel atrial-selective antiarrhythmic compound AVE1231. J Cardiovasc Pharmacol 2008; 51:380-7. [PMID: 18427281 DOI: 10.1097/fjc.0b013e3181669030] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
OBJECTIVE Atrial-selective drug therapy represents a novel therapeutic approach for atrial fibrillation management. The aim of the present study was to investigate the mechanism of hKv1.5 channel inhibition by the atrial-selective compound AVE1231. METHODS Ionic currents were recorded from CHO cells transfected with KCNA5 cDNA with whole-cell patch-clamp technique. The effect of AVE1231 on human atrial cell action potentials was explored with a computer model. RESULTS KCNA5 expression resulted in typical K currents that activated and inactivated voltage dependently. Ascending concentrations of AVE1231 (0.1-100 microM) led to concentration- and voltage-dependent current inhibition (IC50 at +40 mV: 2.0 +/- 0.5 microM, Hill coefficient 0.69 +/- 0.12). Acceleration of hKv1.5 current inactivation occurred with increasing AVE1231 concentrations, indicating channel inhibition in the open state (eg, taufast at +40 mV: 318 +/- 92 milliseconds under control; 14 +/- 1 milliseconds with 3 microM, P < 0.05). Using 1/taufast as an approximation of the time course of drug-channel interaction, association rate (K+1) and dissociation rate (K-1) constants were 8.18 x 10 M/s and 45.95 seconds, respectively (KD = 5.62 microM). The onset of current inhibition occurred more rapidly with higher concentrations along with a prominent tail current crossover phenomenon after AVE1231 application. Drug inhibition remained effective through a range of stimulation frequencies. Computer modeling suggested more pronounced prolongation of action potential duration under conditions of atrial remodeling. CONCLUSION AVE1231 is an inhibitor of hKv1.5 currents with predominant action on channels in their open state; thus, it may be suitable for the treatment of AF.
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Christ T, Wettwer E, Voigt N, Hála O, Radicke S, Matschke K, Várro A, Dobrev D, Ravens U. Pathology-specific effects of the IKur/Ito/IK,ACh blocker AVE0118 on ion channels in human chronic atrial fibrillation. Br J Pharmacol 2008; 154:1619-30. [PMID: 18536759 DOI: 10.1038/bjp.2008.209] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND AND PURPOSE This study was designed to establish the pathology-specific inhibitory effects of the IKur/Ito/IK,ACh blocker AVE0118 on atrium-selective channels and its corresponding effects on action potential shape and effective refractory period in patients with chronic AF (cAF). EXPERIMENTAL APPROACH Outward K+-currents of right atrial myocytes and action potentials of atrial trabeculae were measured with whole-cell voltage clamp and microelectrode techniques, respectively. Outward currents were dissected by curve fitting. KEY RESULTS Four components of outward K+-currents and AF-specific alterations in their properties were identified. Ito was smaller in cAF than in SR, and AVE0118 (10 microM) apparently accelerated its inactivation in both groups without reducing its amplitude. Amplitudes of rapidly and slowly inactivating components of IKur were lower in cAF than in SR. The former was abolished by AVE0118 in both groups, the latter was partially blocked in SR, but not in cAF, even though its inactivation was apparently accelerated in cAF. The large non-inactivating current component was similar in magnitude in both groups, but decreased by AVE0118 only in SR. AVE0118 strongly suppressed AF-related constitutively active IK,ACh and prolonged atrial action potential and effective refractory period exclusively in cAF. CONCLUSIONS AND IMPLICATIONS In atrial myocytes of cAF patients, we detected reduced function of distinct IKur components that possessed decreased component-specific sensitivity to AVE0118 most likely as a consequence of AF-induced electrical remodelling. Inhibition of profibrillatory constitutively active IK,ACh may lead to pathology-specific efficacy of AVE0118 that is likely to contribute to its ability to convert AF into SR.
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Affiliation(s)
- T Christ
- Department of Pharmacology and Toxicology, Dresden University of Technology, Dresden, Germany
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Cherry EM, Hastings HM, Evans SJ. Dynamics of human atrial cell models: restitution, memory, and intracellular calcium dynamics in single cells. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2008; 98:24-37. [PMID: 18617227 DOI: 10.1016/j.pbiomolbio.2008.05.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Mathematical models of cardiac cells have become important tools for investigating the electrophysiological properties and behavior of the heart. As the number of published models increases, it becomes more difficult to choose a model appropriate for the conditions to be studied, especially when multiple models describing the species and region of the heart of interest are available. In this paper, we will review and compare two detailed ionic models of human atrial myocytes, the Nygren et al. model (NM) and the Courtemanche et al. model (CM). Although both models include the same transmembrane currents and are largely based on the same experimental data from human atrial cells, the two models exhibit vastly different properties, especially in their dynamical behavior, including restitution and memory effects. The CM produces pronounced rate adaptation of action potential duration (APD) with limited memory effects, while the NM exhibits strong rate dependence of resting membrane potential (RMP), limited APD restitution, and stronger memory, as well as delayed afterdepolarizations and auto-oscillatory behavior upon cessation of rapid pacing. Channel conductance modifications based on experimentally measured changes during atrial fibrillation modify rate adaptation and memory in both models, but do not change the primary rate-dependent properties of APD and RMP for the CM and NM, respectively. Two sets of proposed changes to the NM that yield a spike-and-dome action potential morphology qualitatively similar to the CM at slow pacing rates similarly do not change the underlying dynamics of the model. Moreover, interchanging the formulations of all transmembrane currents between the two models while leaving calcium handling and ionic concentrations intact indicates that the currents strongly influence memory and the rate adaptation of RMP, while intracellular calcium dynamics primarily determine APD rate adaptation. Our results suggest that differences in intracellular calcium handling between the two human atrial myocyte models are responsible for marked dynamical differences and may prevent reconciliation between the models by straightforward channel conductance modifications.
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Affiliation(s)
- Elizabeth M Cherry
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
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Abstract
Atrial fibrillation (AF) causes substantial morbidity and mortality. It may be triggered and sustained by either reentrant or nonreentrant electrical activity. Human atrial cellular refractory period is shortened in chronic AF, likely aiding reentry. The ionic and molecular mechanisms are not fully understood and may include increased inward rectifier K(+) current and altered Ca(2+) handling. Heart failure, a major cause of AF, may involve arrhythmogenic atrial electrical remodeling, but the pattern is unclear in humans. Beta-blocker therapy prolongs atrial cell refractory period; a potentially antiarrhythmic influence, but the ionic and molecular mechanisms are unclear. The search for drugs to suppress AF without causing ventricular arrhythmias has been aided by basic studies of cellular mechanisms of AF. It remains to be seen whether such drugs will improve patient treatment.
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Affiliation(s)
- Antony J Workman
- British Heart Foundation Glasgow Cardiovascular Research Centre, Faculty of Medicine, University of Glasgow, Glasgow, United Kingdom.
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Yang Q, Wang X, Du L, Li M, You Q. Strategies for atrial fibrillation therapy: focusing onIKurpotassium channel. Expert Opin Ther Pat 2007. [DOI: 10.1517/13543776.17.12.1443] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
Atrial fibrillation (AF) is the most common encountered sustained arrhythmia in clinical practice. The last decade the result of large 'rate' versus 'rhythm' control trials have been published that have changed the current day practise of AF treatment. It has become clear that rate control is at least equally effective as a rhythm control strategy in ameliorating morbidity as well as mortality. Moreover, in each individual patient the risk of thromboembolic events should be assessed and antithrombotic treatment be initiated. There have also been great advances in understanding the mechanisms of AF. Experimental studies showed that as a result of electrical and structural remodelling of the atria, 'AF begets AF'. Pharmacological prevention of atrial electrical remodelling has been troublesome, but it seems that blockers of the renin angiotensin system, and perhaps statins, may reduce atrial structural remodelling by preventing atrial fibrosis. Clinical studies demonstrated that the pulmonary veins exhibit foci that can act as initiator and perpetuator of the arrhythmia. Isolation of the pulmonary veins using radiofrequency catheter ablation usually abolishes AF. The most promising advances in the pharmacological treatment of AF include atrial specific antiarrhythmic drugs and direct thrombin inhibitors. In the present review we will describe the results of recent experimental studies, discuss the latest clinical trials, and we will focus on novel treatment modalities.
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Affiliation(s)
- Y Blaauw
- Department of Cardiology, University Hospital Maastricht, Maastricht, The Netherlands
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Nattel S, Maguy A, Le Bouter S, Yeh YH. Arrhythmogenic Ion-Channel Remodeling in the Heart: Heart Failure, Myocardial Infarction, and Atrial Fibrillation. Physiol Rev 2007; 87:425-56. [PMID: 17429037 DOI: 10.1152/physrev.00014.2006] [Citation(s) in RCA: 597] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Rhythmic and effective cardiac contraction depends on appropriately timed generation and spread of cardiac electrical activity. The basic cellular unit of such activity is the action potential, which is shaped by specialized proteins (channels and transporters) that control the movement of ions across cardiac cell membranes in a highly regulated fashion. Cardiac disease modifies the operation of ion channels and transporters in a way that promotes the occurrence of cardiac rhythm disturbances, a process called “arrhythmogenic remodeling.” Arrhythmogenic remodeling involves alterations in ion channel and transporter expression, regulation and association with important protein partners, and has important pathophysiological implications that contribute in major ways to cardiac morbidity and mortality. We review the changes in ion channel and transporter properties associated with three important clinical and experimental paradigms: congestive heart failure, myocardial infarction, and atrial fibrillation. We pay particular attention to K+, Na+, and Ca2+channels; Ca2+transporters; connexins; and hyperpolarization-activated nonselective cation channels and discuss the mechanisms through which changes in ion handling processes lead to cardiac arrhythmias. We highlight areas of future investigation, as well as important opportunities for improved therapeutic approaches that are being opened by an improved understanding of the mechanisms of arrhythmogenic remodeling.
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Affiliation(s)
- Stanley Nattel
- Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Quebec, Canada.
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Workman AJ, Pau D, Redpath CJ, Marshall GE, Russell JA, Kane KA, Norrie J, Rankin AC. Post-operative atrial fibrillation is influenced by beta-blocker therapy but not by pre-operative atrial cellular electrophysiology. J Cardiovasc Electrophysiol 2007; 17:1230-8. [PMID: 17074009 PMCID: PMC2518219 DOI: 10.1111/j.1540-8167.2006.00592.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
INTRODUCTION We investigated whether post-cardiac surgery (CS) new-onset atrial fibrillation (AF) is predicted by pre-CS atrial cellular electrophysiology, and whether the antiarrhythmic effect of beta-blocker therapy may involve pre-CS pharmacological remodeling. METHODS AND RESULTS Atrial myocytes were obtained from consenting patients in sinus rhythm, just prior to CS. Action potentials and ion currents were recorded using whole-cell patch-clamp technique. Post-CS AF occurred in 53 of 212 patients (25%). Those with post-CS AF were older than those without (67 +/- 2 vs 62 +/- 1 years, P = 0.005). In cells from patients with post-CS AF, the action potential duration at 50% and 90% repolarization, maximum upstroke velocity, and effective refractory period (ERP) were 13 +/- 4 ms, 217 +/- 16 ms, 185 +/- 10 V/s, and 216 +/- 14 ms, respectively (n = 30 cells, 11 patients). Peak L-type Ca(2+) current, transient outward and inward rectifier K(+) currents, and the sustained outward current were -5.0 +/- 0.5, 12.9 +/- 2.4, -4.1 +/- 0.4, and 9.7 +/- 1.0 pA/pF, respectively (13-62 cells, 7-19 patients). None of these values were significantly different in cells from patients without post-CS AF (P > 0.05 for each, 60-279 cells, 29-86 patients), confirmed by multiple and logistic regression. In patients treated >7 days with a beta-blocker pre-CS, the incidence of post-CS AF was lower than in non-beta-blocked patients (13% vs 27%, P = 0.038). Pre-CS beta-blockade was associated with a prolonged pre-CS atrial cellular ERP (P = 0.001), by a similar degree (approximately 20%) in those with and without post-CS AF. CONCLUSION Pre-CS human atrial cellular electrophysiology does not predict post-CS AF. Chronic beta-blocker therapy is associated with a reduced incidence of post-CS AF, unrelated to a pre-CS ERP-prolonging effect of this treatment.
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Affiliation(s)
- Antony J Workman
- BHF Glasgow Cardiovascular Research Centre, University of Glasgow, 126 University Place, Glasgow G12 8TA, United Kingdom.
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Nattel S. Preoperative atrial cardiomyocyte ionic currents and postoperative AF: important insights into what is not the mechanism. J Cardiovasc Electrophysiol 2006; 17:1239-41. [PMID: 16995887 DOI: 10.1111/j.1540-8167.2006.00625.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Gassanov N, Brandt MC, Michels G, Lindner M, Er F, Hoppe UC. Angiotensin II-induced changes of calcium sparks and ionic currents in human atrial myocytes: potential role for early remodeling in atrial fibrillation. Cell Calcium 2006; 39:175-86. [PMID: 16303176 DOI: 10.1016/j.ceca.2005.10.008] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2005] [Revised: 10/11/2005] [Accepted: 10/17/2005] [Indexed: 10/25/2022]
Abstract
AIMS Atrial angiotensin II (ANG II) levels have been shown to be increased in atrial fibrillation (AF). The purpose of the study was to evaluate a potential role of ANG II in the early remodeling and susceptibility to chronicization of AF. METHODS AND RESULTS Isolated human atrial myocytes were incubated in ANG II and/or angiotensin type 1 receptor blocker candesartan. ANG II markedly increased the frequency of spontaneous Ca(2+) sparks, spark full duration, time to peak Ca(2+) fluorescence and decay time measured by confocal imaging. Sarcoplasmic reticulum calcium content estimated by caffeine-evoked calcium release did not differ between ANG II-treated cells and controls. Patch-clamp recordings revealed that ANG II significantly decreased I(to) and increased I(Ca,L) current densities. Candesartan blocked these ANG II-mediated alterations. ANG II exhibited no effect on I(K1), I(Kur) and I(f) current size. Expression of connexin 40 and connexin 43 was not significantly changed by ANG II as assessed by immunohistochemistry and Western blot analysis. CONCLUSION ANG II-induced alterations of calcium handling and electrophysiological changes in human atrial cells similar to those previously observed in the onset of AF. Prevention of these alterations by candesartan might constitute a useful pharmacological strategy for the treatment of AF.
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Affiliation(s)
- Natig Gassanov
- Department of Internal Medicine III, University of Cologne, Kerpener Str. 62, Cologne 50937, Germany
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