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Keidar N, Peretz NK, Yaniv Y. Ca 2+ pushes and pulls energetics to maintain ATP balance in atrial cells: computational insights. Front Physiol 2023; 14:1231259. [PMID: 37528893 PMCID: PMC10387757 DOI: 10.3389/fphys.2023.1231259] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 07/03/2023] [Indexed: 08/03/2023] Open
Abstract
To maintain atrial function, ATP supply-to-demand matching must be tightly controlled. Ca2+ can modulate both energy consumption and production. In light of evidence suggesting that Ca2+ affects energetics through "push" (activating metabolite flux and enzymes in the Krebs cycle to push the redox flux) and "pull" (acting directly on ATP synthase and driving the redox flux through the electron transport chain and increasing ATP production) pathways, we investigated whether both pathways are necessary to maintain atrial ATP supply-to-demand matching. Rabbit right atrial cells were electrically stimulated at different rates, and oxygen consumption and flavoprotein fluorescence were measured. To gain mechanistic insight into the regulators of ATP supply-to-demand matching in atrial cells, models of atrial electrophysiology, Ca2+ cycling and force were integrated with a model of mitochondrial Ca2+ and a modified model of mitochondrial energy metabolism. The experimental results showed that oxygen consumption increased in response to increases in the electrical stimulation rate. The model reproduced these findings and predicted that the increase in oxygen consumption is associated with metabolic homeostasis. The model predicted that Ca2+ must act both in "push" and "pull" pathways to increase oxygen consumption. In contrast to ventricular trabeculae, no rapid time-dependent changes in mitochondrial flavoprotein fluorescence were measured upon an abrupt change in workload. The model reproduced these findings and predicted that the maintenance of metabolic homeostasis is due to the effects of Ca2+ on ATP production. Taken together, this work provides evidence of Ca2+ "push" and "pull" activity to maintain metabolic homeostasis in atrial cells.
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Changes in cAMP signaling are associated with age-related downregulation of spontaneously beating atrial tissue energetic indices. GeroScience 2022; 45:209-219. [PMID: 35790659 PMCID: PMC9886694 DOI: 10.1007/s11357-022-00609-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 06/15/2022] [Indexed: 02/03/2023] Open
Abstract
The prevalence of atria-related diseases increases exponentially with age and is associated with ATP supply-to-demand imbalances. Because evidence suggests that cAMP regulates ATP supply-to-demand, we explored aged-associated alterations in atrial ATP supply-to-demand balance and its correlation with cAMP levels. Right atrial tissues driven by spontaneous sinoatrial node impulses were isolated from aged (22-26 months) and adult (3-4 months) C57/BL6 mice. ATP demand increased by addition of isoproterenol or 3-Isobutyl-1-methylxanthine (IBMX) and decreased by application of carbachol. Each drug was administrated at the dose that led to a maximal change in beating rate (Xmax) and to 50% of that maximal change in adult tissue (X50). cAMP, NADH, NAD + NADH, and ATP levels were measured in the same tissue. The tight correlation between cAMP levels and the beating rate (i.e., the ATP demand) demonstrated in adult atria was altered in aged atria. cAMP levels were lower in aged compared to adult atrial tissue exposed to X50 of ISO or IBMX, but this difference narrowed at Xmax. Neither ATP nor NADH levels correlated with ATP demand in either adult or aged atria. Baseline NADH levels were lower in aged as compared to adult atria, but were restored by drug perturbations that increased cAMP levels. Reduction in Ca2+-activated adenylyl cyclase-induced decreased cAMP and prolongation of the spontaneous beat interval of adult atrial tissue to their baseline levels in aged tissue, brought energetics indices to baseline levels in aged tissue. Thus, cAMP regulates right atrial ATP supply-to-demand matching and can restore age-associated ATP supply-to-demand imbalance.
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Young LJ, Antwi-Boasiako S, Ferrall J, Wold LE, Mohler PJ, El Refaey M. Genetic and non-genetic risk factors associated with atrial fibrillation. Life Sci 2022; 299:120529. [PMID: 35385795 PMCID: PMC9058231 DOI: 10.1016/j.lfs.2022.120529] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/08/2022] [Accepted: 03/31/2022] [Indexed: 12/15/2022]
Abstract
Atrial fibrillation (AF) is the most common arrhythmic disorder and its prevalence in the United States is projected to increase to more than twelve million cases in 2030. AF increases the risk of other forms of cardiovascular disease, including stroke. As the incidence of atrial fibrillation increases dramatically with age, it is paramount to elucidate risk factors underlying AF pathogenesis. Here, we review tissue and cellular pathways underlying AF, as well as critical components that impact AF susceptibility including genetic and environmental risk factors. Finally, we provide the latest information on potential links between SARS-CoV-2 and human AF. Improved understanding of mechanistic pathways holds promise in preventative care and early diagnostics, and also introduces novel targeted forms of therapy that might attenuate AF progression and maintenance.
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Affiliation(s)
- Lindsay J Young
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - Steve Antwi-Boasiako
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - Joel Ferrall
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA
| | - Loren E Wold
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA; College of Nursing, The Ohio State University, Columbus, OH, USA
| | - Peter J Mohler
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA; Department of Internal Medicine, Division of Cardiovascular Medicine, The Ohio State University, Columbus, OH, USA
| | - Mona El Refaey
- The Frick Center for Heart Failure and Arrhythmia, Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, USA; Department of Surgery, Division of Cardiac Surgery, The Ohio State University, Columbus, OH, USA.
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4
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Guo F, Tang C, Huang B, Gu L, Zhou J, Mo Z, Liu C, Liu Y. LncRNA H19 Drives Proliferation of Cardiac Fibroblasts and Collagen Production via Suppression of the miR-29a-3p/miR-29b-3p-VEGFA/TGF-β Axis. Mol Cells 2022; 45:122-133. [PMID: 34887365 PMCID: PMC8926865 DOI: 10.14348/molcells.2021.0066] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Revised: 09/27/2021] [Accepted: 09/29/2021] [Indexed: 11/27/2022] Open
Abstract
The aim of this study was to investigating whether lncRNA H19 promotes myocardial fibrosis by suppressing the miR-29a-3p/miR-29b-3p-VEGFA/TGF-β axis. Patients with atrial fibrillation (AF) and healthy volunteers were included in the study, and their biochemical parameters were collected. In addition, pcDNA3.1-H19, si-H19, and miR-29a/b-3p mimic/inhibitor were transfected into cardiac fibroblasts (CFs), and proliferation of CFs was detected by MTT assay. Expression of H19 and miR-29a/b-3p were detected using real-time quantitative polymerase chain reaction, and expression of α-smooth muscle actin (α-SMA), collagen I, collagen II, matrix metalloproteinase-2 (MMP-2), and elastin were measured by western blot analysis. The dual luciferase reporter gene assay was carried out to detect the sponging relationship between H19 and miR-29a/b-3p in CFs. Compared with healthy volunteers, the level of plasma H19 was significantly elevated in patients with AF, while miR-29a-3p and miR-29b-3p were markedly depressed (P < 0.05). Serum expression of lncRNA H19 was negatively correlated with the expression of miR-29a-3p and miR-29b-3p among patients with AF (rs = -0.337, rs = -0.236). Moreover, up-regulation of H19 expression and down-regulation of miR-29a/b-3p expression facilitated proliferation and synthesis of extracellular matrix (ECM)-related proteins. SB431542 and si-VEGFA are able to reverse the promotion of miR-29a/b-3p on proliferation of CFs and ECM-related protein synthesis. The findings of the present study suggest that H19 promoted CF proliferation and collagen synthesis by suppressing the miR-29a-3p/miR-29b-3p-VEGFA/TGF-β axis, and provide support for a potential new direction for the treatment of AF.
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Affiliation(s)
- Feng Guo
- Department of Cardiology, Shanghai Electric Power Hospital, Shanghai 200050, China
| | - Chengchun Tang
- Department of Cardiology, Zhongda Hospital Southeast University, Nanjing 210009, China
| | - Bo Huang
- Department of Cardiology, Shanghai Electric Power Hospital, Shanghai 200050, China
| | - Lifei Gu
- Department of Cardiology, Shanghai Electric Power Hospital, Shanghai 200050, China
| | - Jun Zhou
- Department of Cardiology, Shanghai Electric Power Hospital, Shanghai 200050, China
| | - Zongyang Mo
- Department of Cardiology, Shanghai Electric Power Hospital, Shanghai 200050, China
| | - Chang Liu
- Department of Cardiology, Shanghai Electric Power Hospital, Shanghai 200050, China
| | - Yuqing Liu
- Department of Emergency, Naval Characteristic Medical Center Affiliated to Shanghai, Naval Medical University, Shanghai 200433, China
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Liao J, Zhang S, Yang S, Lu Y, Lu K, Wu Y, Wu Q, Zhao N, Dong Q, Chen L, Du Y. Interleukin-6-Mediated-Ca 2+ Handling Abnormalities Contributes to Atrial Fibrillation in Sterile Pericarditis Rats. Front Immunol 2022; 12:758157. [PMID: 34975847 PMCID: PMC8716408 DOI: 10.3389/fimmu.2021.758157] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 11/30/2021] [Indexed: 02/05/2023] Open
Abstract
Pre-existing Ca2+ handling abnormalities constitute the arrhythmogenic substrate in patients developing postoperative atrial fibrillation (POAF), a common complication after cardiac surgery. Postoperative interleukin (IL)-6 levels are associated with atrial fibrosis in several animal models of POAF, contributing to atrial arrhythmias. Here, we hypothesize that IL-6-mediated-Ca2+ handling abnormalities contribute to atrial fibrillation (AF) in sterile pericarditis (SP) rats, an animal model of POAF. SP was induced in rats by dusting atria with sterile talcum powder. Anti-rat-IL-6 antibody (16.7 μg/kg) was administered intraperitoneally at 30 min after the recovery of anesthesia. In vivo electrophysiology, ex vivo optical mapping, western blots, and immunohistochemistry were performed to elucidate mechanisms of AF susceptibility. IL-6 neutralization ameliorated atrial inflammation and fibrosis, as well as AF susceptibility in vivo and the frequency of atrial ectopy and AF with a reentrant pattern in SP rats ex vivo. IL-6 neutralization reversed the prolongation and regional heterogeneity of Ca2+ transient duration, relieved alternans, reduced the incidence of discordant alternans, and prevented the reduction and regional heterogeneity of the recovery ratio of Ca2+ transient. In agreement, western blots showed that IL-6 neutralization reversed the reduction in the expression of ryanodine receptor 2 (RyR2) and phosphorylated phospholamban. Acute IL-6 administration to isolated rat hearts recapitulated partial Ca2+ handling phenotype in SP rats. In addition, intraperitoneal IL-6 administration to rats increased AF susceptibility, independent of fibrosis. Our results reveal that IL-6-mediated-Ca2+ handling abnormalities in SP rats, especially RyR2-dysfunction, independent of IL-6-induced-fibrosis, early contribute to the development of POAF by increasing propensity for arrhythmogenic alternans.
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Affiliation(s)
- Jie Liao
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Research Center of Ion Channelopathy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Lab for Biological Targeted Therapy of Education Ministry and Hubei Province, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Department of Cardiology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
| | - Shaoshao Zhang
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Research Center of Ion Channelopathy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Lab for Biological Targeted Therapy of Education Ministry and Hubei Province, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Shuaitao Yang
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Research Center of Ion Channelopathy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Lab for Biological Targeted Therapy of Education Ministry and Hubei Province, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yang Lu
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Research Center of Ion Channelopathy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Lab for Biological Targeted Therapy of Education Ministry and Hubei Province, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Kai Lu
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Research Center of Ion Channelopathy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Lab for Biological Targeted Therapy of Education Ministry and Hubei Province, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yuwei Wu
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Research Center of Ion Channelopathy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Lab for Biological Targeted Therapy of Education Ministry and Hubei Province, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qiongfeng Wu
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Research Center of Ion Channelopathy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Lab for Biological Targeted Therapy of Education Ministry and Hubei Province, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Ning Zhao
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Research Center of Ion Channelopathy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Lab for Biological Targeted Therapy of Education Ministry and Hubei Province, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Qian Dong
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Research Center of Ion Channelopathy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Lab for Biological Targeted Therapy of Education Ministry and Hubei Province, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Lei Chen
- Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Yimei Du
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Research Center of Ion Channelopathy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Institute of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.,Key Lab for Biological Targeted Therapy of Education Ministry and Hubei Province, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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6
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Koniari I, Artopoulou E, Velissaris D, Ainslie M, Mplani V, Karavasili G, Kounis N, Tsigkas G. Biomarkers in the clinical management of patients with atrial fibrillation and heart failure. J Geriatr Cardiol 2021; 18:908-951. [PMID: 34908928 PMCID: PMC8648548 DOI: 10.11909/j.issn.1671-5411.2021.11.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Atrial fibrillation (AF) and heart failure (HF) are two cardiovascular diseases with an increasing prevalence worldwide. These conditions share common pathophysiologiesand frequently co-exit. In fact, the occurrence of either condition can 'cause' the development of the other, creating a new patient group that demands different management strategies to that if they occur in isolation. Regardless of the temproral association of the two conditions, their presence is linked with adverse cardiovascular outcomes, increased rate of hospitalizations, and increased economic burden on healthcare systems. The use of low-cost, easily accessible and applicable biomarkers may hasten the correct diagnosis and the effective treatment of AF and HF. Both AF and HF effect multiple physiological pathways and thus a great number of biomarkers can be measured that potentially give the clinician important diagnostic and prognostic information. These will then guide patient centred therapeutic management. The current biomarkers that offer potential for guiding therapy, focus on the physiological pathways of miRNA, myocardial stretch and injury, oxidative stress, inflammation, fibrosis, coagulation and renal impairment. Each of these has different utility in current clinincal practice.
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Affiliation(s)
- Ioanna Koniari
- Manchester Heart Institute, Manchester University Foundation Trust, Manchester, United Kingdom
| | - Eleni Artopoulou
- Department of Internal Medicine, University Hospital of Patras, Patras, Greece
| | | | - Mark Ainslie
- Manchester Heart Institute, Manchester University Foundation Trust, Manchester, United Kingdom
- Division of Cardiovascular Sciences, University of Manchester
| | - Virginia Mplani
- Department of Cardiology, University Hospital of Patras, Patras, Greece
| | - Georgia Karavasili
- Manchester Heart Institute, Manchester University Foundation Trust, Manchester, United Kingdom
| | - Nicholas Kounis
- Department of Cardiology, University Hospital of Patras, Patras, Greece
| | - Grigorios Tsigkas
- Department of Cardiology, University Hospital of Patras, Patras, Greece
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7
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Wong CK, Tse HF. New methodological approaches to atrial fibrillation drug discovery. Expert Opin Drug Discov 2020; 16:319-329. [PMID: 33016154 DOI: 10.1080/17460441.2021.1826432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Atrial fibrillation (AF) is the most common arrhythmia encountered in clinical practice and rhythm control using pharmacological agents is required in selected patients. Nonetheless, current medication is only modestly efficacious and associated with significant cardiovascular and systemic side effects. More efficacious and safe drugs are required to restore and maintain sinus rhythm in patients with AF. AREAS COVERED In this review, several potential drug targets are discussed including trans-membrane ion channels, intracellular calcium signaling, gap junction signaling, atrial inflammation and fibrosis, and the autonomic nervous system. New tools and methodologies for AF drug development are also reviewed including gene therapy, genome-guided therapy, stem cell technologies, tissue engineering, and optogenetics. EXPERT OPINION In recent decades, there has been an increased understanding of the underlying pathogenesis of AF. As a result, there is a gradual paradigm shift from focusing only on trans-membrane ion channel inhibition to developing therapeutic agents that target other underlying arrhythmogenic mechanisms. Gene therapy and genome-guided therapy are emerging as novel treatments for AF with some success in proof-of-concept studies. Recent advances in stem cell technology, tissue engineering, and optogenetics may allow more effective in-vitro drug screening than conventional methodologies.
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Affiliation(s)
- Chun-Ka Wong
- Cardiology Division, Department of Medicine, The University of Hong Kong, Hong Kong, SAR China
| | - Hung-Fat Tse
- Cardiology Division, Department of Medicine, The University of Hong Kong, Hong Kong, SAR China
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8
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The Therapeutic Potential of MicroRNAs in Atrial Fibrillation. Mediators Inflamm 2020; 2020:3053520. [PMID: 32256190 PMCID: PMC7091547 DOI: 10.1155/2020/3053520] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 03/03/2020] [Indexed: 12/12/2022] Open
Abstract
One of the most globally prevalent supraventricular arrhythmias is atrial fibrillation (AF). Knowledge of the structures and functions of messenger RNA (mRNA) has recently increased. It is no longer viewed as solely an intermediate molecule between DNA and proteins but has come to be seen as a dynamic and modifiable gene regulator. This new perspective on mRNA has led to rising interest in it and its presence in research into new therapeutic schemes. This paper, therefore, focuses on microRNAs (miRNAs), which are small noncoding RNAs that regulate posttranscriptional gene expression and play a vital role in the physiology and normative development of cardiovascular systems. This means they play an equally vital role in the development and progression of cardiovascular diseases. In recent years, multiple studies have pinpointed particular miRNA expression profiles as being associated with varying histological features of AF. These studies have been carried out in both animal models and AF patients. The emergence of miRNAs as biomarkers and their therapeutic potential in AF patients will be discussed in the body of this paper.
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Yang X, An N, Zhong C, Guan M, Jiang Y, Li X, Zhang H, Wang L, Ruan Y, Gao Y, Liu N, Shang H, Xing Y. Enhanced cardiomyocyte reactive oxygen species signaling promotes ibrutinib-induced atrial fibrillation. Redox Biol 2020; 30:101432. [PMID: 31986467 PMCID: PMC6994714 DOI: 10.1016/j.redox.2020.101432] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 12/27/2019] [Accepted: 01/12/2020] [Indexed: 12/12/2022] Open
Abstract
Atrial fibrillation (AF) occurs in up to 11% of cancer patients treated with ibrutinib. The pathophysiology of ibrutinib promoted AF is complicated, as there are multiple interactions involved; the detailed molecular mechanisms underlying this are still unclear. Here, we aimed to determine the electrophysiological and molecular mechanisms of burst-pacing-induced AF in ibrutinib-treated mice. The results indicated differentially expressed proteins in ibrutinib-treated mice, identified through proteomic analysis, were found to play a role in oxidative stress-related pathways. Finally, treatment with an inhibitor of NADPH oxidase (NOX) prevented and reversed AF development in ibrutinib-treated mice. It was showed that the related protein expression of reactive oxygen species (ROS) in the ibrutinib group was significantly increased, including NOX2, NOX4, p22-phox, XO and TGF-β protein expression. It was interesting that ibrutinib group also significantly increased the expression of ox-CaMKII, p-CaMKII (Thr-286) and p-RyR2 (Ser2814), causing enhanced abnormal sarcoplasmic reticulum (SR) Ca2+ release and mitochondrial structures, as well as atrial fibrosis and atrial hypertrophy in ibrutinib-treated mice, and apocynin reduced the expression of these proteins. Ibrutinib-treated mice were also more likely to develop AF, and AF occurred over longer periods. In conclusion, our study has established a pathophysiological role for ROS signaling in atrial cardiomyocytes, and it may be that ox-CaMKII and p-CaMKII (Thr-286) are activated by ROS to increase AF susceptibility following ibrutinib treatment. We have also identified the inhibition of NOX as a potential novel AF therapy approach.
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Affiliation(s)
- Xinyu Yang
- Key Laboratory of Chinese Internal Medicine of the Ministry of Education, Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, 100700, China; Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China
| | - Na An
- Key Laboratory of Chinese Internal Medicine of the Ministry of Education, Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, 100700, China; Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China
| | - Changming Zhong
- Key Laboratory of Chinese Internal Medicine of the Ministry of Education, Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, 100700, China
| | - Manke Guan
- Key Laboratory of Chinese Internal Medicine of the Ministry of Education, Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, 100700, China
| | - Yuchen Jiang
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China
| | - Xinye Li
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China
| | - Hanlai Zhang
- Key Laboratory of Chinese Internal Medicine of the Ministry of Education, Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, 100700, China
| | - Liqin Wang
- Key Laboratory of Chinese Internal Medicine of the Ministry of Education, Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, 100700, China
| | - Yanfei Ruan
- Department of Cardiology, Beijing An Zhen Hospital of the Capital University of Medical Sciences, Beijing, 100853, PR China
| | - Yonghong Gao
- Key Laboratory of Chinese Internal Medicine of the Ministry of Education, Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, 100700, China
| | - Nian Liu
- Department of Cardiology, Beijing An Zhen Hospital of the Capital University of Medical Sciences, Beijing, 100853, PR China.
| | - Hongcai Shang
- Key Laboratory of Chinese Internal Medicine of the Ministry of Education, Dongzhimen Hospital Affiliated to Beijing University of Chinese Medicine, Beijing, 100700, China.
| | - Yanwei Xing
- Guang'anmen Hospital, China Academy of Chinese Medical Sciences, Beijing, 100053, China.
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10
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Shiferaw Y, Aistrup GL, Louch WE, Wasserstrom JA. Remodeling Promotes Proarrhythmic Disruption of Calcium Homeostasis in Failing Atrial Myocytes. Biophys J 2019; 118:476-491. [PMID: 31889516 DOI: 10.1016/j.bpj.2019.12.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 11/19/2019] [Accepted: 12/09/2019] [Indexed: 01/31/2023] Open
Abstract
It is well known that heart failure (HF) typically coexists with atrial fibrillation (AF). However, until now, no clear mechanism has been established that relates HF to AF. In this study, we apply a multiscale computational framework to establish a mechanistic link between atrial myocyte structural remodeling in HF and AF. Using a spatially distributed model of calcium (Ca) signaling, we show that disruption of the spatial relationship between L-type Ca channels (LCCs) and ryanodine receptors results in markedly increased Ca content of the sarcoplasmic reticulum (SR). This increase in SR load is due to changes in the balance between Ca entry via LCCs and Ca extrusion due to the sodium-calcium exchanger after an altered spatial relationship between these signaling proteins. Next, we show that the increased SR load in atrial myocytes predisposes these cells to subcellular Ca waves that occur during the action potential (AP) and are triggered by LCC openings. These waves are common in atrial cells because of the absence of a well-developed t-tubule system in most of these cells. This distinct spatial architecture allows for the presence of a large pool of orphaned ryanodine receptors, which can fire and sustain Ca waves during the AP. Finally, we incorporate our atrial cell model in two-dimensional tissue simulations and demonstrate that triggered wave generation in cells leads to electrical waves in tissue that tend to fractionate to form wavelets of excitation. This fractionation is driven by the underlying stochasticity of subcellular Ca waves, which perturbs AP repolarization and consequently induces localized conduction block in tissue. We outline the mechanism for this effect and argue that it may explain the propensity for atrial arrhythmias in HF.
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Affiliation(s)
- Yohannes Shiferaw
- Department of Physics, California State University, Northridge, California.
| | - Gary L Aistrup
- Department of Experimental Cardiology, Masonic Medical Research Institute, Utica, New York
| | - William E Louch
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway; KG Jebsen Center for Cardiac Research, University of Oslo, Oslo, Norway
| | - J A Wasserstrom
- Department of Medicine (Cardiology) and The Feinberg Cardiovascular and Renal Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
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Modulation of miR-10a-mediated TGF-β1/Smads signaling affects atrial fibrillation-induced cardiac fibrosis and cardiac fibroblast proliferation. Biosci Rep 2019; 39:BSR20181931. [PMID: 30683806 PMCID: PMC6367129 DOI: 10.1042/bsr20181931] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 01/10/2019] [Accepted: 01/25/2019] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) rat models and rat cardiac fibroblasts (CFs) with overexpressed or inhibited miR-10a were used to investigate the possible role of miR-10a-mediated transforming growth factor-β (TGF-β1)/Smads signaling in cardiac fibrosis and fibroblast proliferation in rats with AF. Gene ontology and pathway enrichment analyses were used to identify the possible function of miR-10a in cardiac fibrosis. The results showed that overexpressed miR-10a significantly prolonged the duration of AF, further elevated the collagen volume fraction (CVF), and increased the viability of CFs in AF rats; these findings were in contrast with the findings for rats with inhibition of miR-10a (all P<0.05). Moreover, miR-10a overexpression could promote miR-10a, collagen-I, collagen III, α-SMA, and TGF-β1 protein expression and increase the levels of hydroxyproline but reduced Smad7 protein expression in atrial tissues and CFs in AF rats. Not surprisingly, inhibiting miR-10a led to completely contrasting results (all P<0.05). Moreover, TGF-β1 treatment could reverse the inhibitory effect of miR-10a down-regulation on cardiac fibrosis in CFs. Bioinformatics analysis and luciferase reporter assay results demonstrated that miR-10a bound directly to the 3′-UTR of BCL6, which is involved in cell growth and proliferation. Thus, our study indicate that down-regulation of miR-10a may inhibit collagen formation, reduce atrial structure remodeling, and decrease proliferation of CFs, eventually suppressing cardiac fibrosis in AF rats via inhibition of the TGF-β1/Smads signaling pathway.
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12
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Dan GA, Dobrev D. Antiarrhythmic drugs for atrial fibrillation: Imminent impulses are emerging. IJC HEART & VASCULATURE 2018; 21:11-15. [PMID: 30225340 PMCID: PMC6138883 DOI: 10.1016/j.ijcha.2018.08.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 08/15/2018] [Accepted: 08/30/2018] [Indexed: 12/19/2022]
Abstract
Rhythm and rate strategies are considered equivalent for the management of atrial fibrillation (AF). Moreover, both strategies are intended for improving symptoms and quality of life. Despite the clinical availability of several antiarrhythmic drugs (AAD) the alternatives for the patient with comorbidities are significantly fewer because of the concern regarding many adverse effects, including proarrhythmias. The impetuous development of AF ablation gave rise to a false impression that AAD are a second line therapy. All these statements reflect, in fact, the weakness of the classical paradigm and classification regarding AAD and the gap between the current knowledge of AF mechanism and determinants and the "classical" AAD non-discriminatory action. A new paradigm in development of effective and safe AAD is based on modern knowledge of vulnerable parameters involved in the genesis and perpetuation of AF. New AAD will target specific triggers of AF and ion currents which are expressed preferentially in fibrillatory atrium. Such targets will include repolarizing currents and channels, as ultrarapid potassium current, two pore potassium current, the acetylcholine-gated potassium current, small-conductance calcium-dependent potassium channels, but, also, molecular targets involved in intracellular calcium kinetics, as Ca2+-calmodulin-dependent protein kinase, ryanodine receptors and non-coding miRNA. New mechanistic discoveries link AF to inflammation and modern anti-cytokine drugs. There is still a long way to win between basic research and clinical practice, but, without any doubt, antiarrhythmic drug therapy will remain and develop as a cornerstone therapy for AF not in conflict, but complementary and alternative to interventional therapy.
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Affiliation(s)
- Gheorghe-Andrei Dan
- Carol Davila Medicine University, Bucharest, Romania
- Colentina University Hospital, Bucharest, Romania
| | - Dobromir Dobrev
- Institute of Pharmacology, West German Heart and Vascular Center, University Duisburg-Essen, Essen, Germany
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13
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Characterization of circRNA‑associated ceRNA networks in patients with nonvalvular persistent atrial fibrillation. Mol Med Rep 2018; 19:638-650. [PMID: 30483740 DOI: 10.3892/mmr.2018.9695] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 09/13/2018] [Indexed: 11/05/2022] Open
Abstract
Circular RNAs (circRNAs) are non-coding RNAs forming closed-loop structures, and their aberrant expression may lead to disease. However, the potential network of circRNA‑associated competing endogenous RNA (ceRNA) involved in nonvalvular persistent atrial fibrillation (NPAF) has not been previously reported. In the present study, four left atrial appendages (LAA) of patients with NPAF and four normal LAAs were examined via RNA sequencing, and their potential functions were investigated via bioinformatics analysis. The circRNA‑enriched genes were analyzed using Gene Ontology (GO) categories, while the enrichment of circRNAs was detected via the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. A total of 296 significantly dysregulated circRNA transcripts were obtained, with 238 upregulated and 58 downregulated. A number of circRNAs were further confirmed using reverse transcription‑quantitative polymerase chain reaction analysis. Furthermore, the more comprehensive circRNA‑associated ceRNA networks were examined in patients with NPAF. GO categories and KEGG annotation analysis of circRNAs revealed that the circRNA‑associated ceRNA networks were likely to influence AF though alterations in calcium and cardiac muscle contraction. The circRNA‑associated ceRNA networks revealed that dysregulated circRNAs in NPAF may be involved in regulating hsa‑microRNA (miR)‑208b and hsa‑miR‑21. To the best of our knowledge, this study presents the circRNA‑associated ceRNA networks in NPAF for the first time, which may have potential implications for the pathogenesis of AF. This study reveals a potential perspective from which to investigate circRNAs in circRNA‑associated ceRNA networks (hsa_circRNA002085, hsa_circRNA001321) in NPAF, and provides a potential biomarker for AF.
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14
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Role of the TRPM4 Channel in Cardiovascular Physiology and Pathophysiology. Cells 2018; 7:cells7060062. [PMID: 29914130 PMCID: PMC6025450 DOI: 10.3390/cells7060062] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 06/11/2018] [Accepted: 06/14/2018] [Indexed: 12/31/2022] Open
Abstract
The transient receptor potential cation channel subfamily M member 4 (TRPM4) channel influences calcium homeostasis during many physiological activities such as insulin secretion, immune response, respiratory reaction, and cerebral vasoconstriction. This calcium-activated, monovalent, selective cation channel also plays a key role in cardiovascular pathophysiology; for example, a mutation in the TRPM4 channel leads to cardiac conduction disease. Recently, it has been suggested that the TRPM4 channel is also involved in the development of cardiac ischemia-reperfusion injury, which causes myocardial infarction. In the present review, we discuss the physiological function of the TRPM4 channel, and assess its role in cardiovascular pathophysiology.
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15
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Kornej J, Schumacher K, Husser D, Hindricks G. [Biomarkers and atrial fibrillation : Prediction of recurrences and thromboembolic events after rhythm control management]. Herzschrittmacherther Elektrophysiol 2018; 29:219-227. [PMID: 29761335 DOI: 10.1007/s00399-018-0558-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 04/03/2018] [Indexed: 06/08/2023]
Abstract
Atrial fibrillation (AF) is the most common arrhythmia in clinical praxis and is associated with an increased risk for cardio- and cerebrovascular complications leading to an increased mortality. Catheter ablation represents one of the most important and efficient therapy strategies in AF patients. Nevertheless, the high incidence of arrhythmia recurrences after catheter ablation leads to repeated procedures and higher treatment costs. Recently, several scores had been developed to predict rhythm outcomes after catheter ablation. Biomarker research is also of enormous interest. There are many clinical and blood biomarkers pathophysiologically associated with AF occurrence, progression and recurrences. These biomarkers-including different markers in blood (e. g. von Willebrand factor, D‑dimer, natriuretic peptides) or urine (proteins, epidermal grown factor receptor) but also cardiac imaging (echocardiography, computed tomography, magnetic resonance imaging)-could help to improve clinical scores and be useful for individualized AF management and optimized patients' selection for different AF treatment strategies. In this review, the role of diverse biomarkers and their predictive value related to AF-associated complications are discussed.
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Affiliation(s)
- Jelena Kornej
- Abteilung für Rhythmologie, Herzzentrum Leipzig, HELIOS Kliniken GmbH, Strümpellstraße 39, 04289, Leipzig, Deutschland.
| | - Katja Schumacher
- Abteilung für Rhythmologie, Herzzentrum Leipzig, HELIOS Kliniken GmbH, Strümpellstraße 39, 04289, Leipzig, Deutschland
| | - Daniela Husser
- Abteilung für Rhythmologie, Herzzentrum Leipzig, HELIOS Kliniken GmbH, Strümpellstraße 39, 04289, Leipzig, Deutschland
| | - Gerhard Hindricks
- Abteilung für Rhythmologie, Herzzentrum Leipzig, HELIOS Kliniken GmbH, Strümpellstraße 39, 04289, Leipzig, Deutschland
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16
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Shiferaw Y, Aistrup GL, Wasserstrom JA. Mechanism for Triggered Waves in Atrial Myocytes. Biophys J 2017; 113:656-670. [PMID: 28793220 DOI: 10.1016/j.bpj.2017.06.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 06/13/2017] [Accepted: 06/14/2017] [Indexed: 01/27/2023] Open
Abstract
Excitation-contraction coupling in atrial cells is mediated by calcium (Ca) signaling between L-type Ca channels and Ryanodine receptors that occurs mainly at the cell boundary. This unique architecture dictates essential aspects of Ca signaling under both normal and diseased conditions. In this study we apply laser scanning confocal microscopy, along with an experimentally based computational model, to understand the Ca cycling dynamics of an atrial cell subjected to rapid pacing. Our main finding is that when an atrial cell is paced under Ca overload conditions, Ca waves can then nucleate on the cell boundary and propagate to the cell interior. These propagating Ca waves are referred to as "triggered waves" because they are initiated by L-type Ca channel openings during the action potential. These excitations are distinct from spontaneous Ca waves originating from random fluctuations of Ryanodine receptor channels, and which occur after much longer waiting times. Furthermore, we argue that the onset of these triggered waves is a highly nonlinear function of the sarcoplasmic reticulum Ca load. This strong nonlinearity leads to aperiodic response of Ca at rapid pacing rates that is caused by the complex interplay between paced Ca release and triggered waves. We argue further that this feature of atrial cells leads to dynamic instabilities that may underlie atrial arrhythmias. These studies will serve as a starting point to explore the nonlinear dynamics of atrial cells and will yield insights into the trigger and maintenance of atrial fibrillation.
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Affiliation(s)
- Yohannes Shiferaw
- Department of Physics and Astronomy, California State University, Northridge, California.
| | - Gary L Aistrup
- Department of Medicine (Cardiology) and the Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - J Andrew Wasserstrom
- Department of Medicine (Cardiology) and the Feinberg Cardiovascular Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
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17
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Ravens U. Atrial-selective K + channel blockers: potential antiarrhythmic drugs in atrial fibrillation? Can J Physiol Pharmacol 2017; 95:1313-1318. [PMID: 28738160 DOI: 10.1139/cjpp-2017-0024] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In the wake of demographic change in Western countries, atrial fibrillation has reached an epidemiological scale, yet current strategies for drug treatment of the arrhythmia lack sufficient efficacy and safety. In search of novel medications, atrial-selective drugs that specifically target atrial over other cardiac functions have been developed. Here, I will address drugs acting on potassium (K+) channels that are either predominantly expressed in atria or possess electrophysiological properties distinct in atria from ventricles. These channels include the ultra-rapidly activating, delayed outward-rectifying Kv1.5 channel conducting IKur, the acetylcholine-activated inward-rectifying Kir3.1/Kir3.4 channel conducting IK,ACh, the Ca2+-activated K+ channels of small conductance (SK) conducting ISK, and the two-pore domain K+ (K2P) channels (tandem of P domains, weak inward-rectifying K+ channels (TWIK-1), TWIK-related acid-sensitive K+ channels (TASK-1 and TASK-3)) that are responsible for voltage-independent background currents ITWIK-1, ITASK-1, and ITASK-3. Direct drug effects on these channels are described and their putative value in treatment of atrial fibrillation is discussed. Although many potential drug targets have emerged in the process of unravelling details of the pathophysiological mechanisms responsible for atrial fibrillation, we do not know whether novel antiarrhythmic drugs will be more successful when modulating many targets or a single specific one. The answer to this riddle can only be solved in a clinical context.
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Affiliation(s)
- Ursula Ravens
- Institute of Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, University of Freiburg, Germany; Institute of Physiology, Medical Faculty Carl Gustav Carus, TU Dresden, Germany.,Institute of Experimental Cardiovascular Medicine, University Heart Center Freiburg - Bad Krozingen, University of Freiburg, Germany; Institute of Physiology, Medical Faculty Carl Gustav Carus, TU Dresden, Germany
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18
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Abstract
Cardiac arrhythmias can follow disruption of the normal cellular electrophysiological processes underlying excitable activity and their tissue propagation as coherent wavefronts from the primary sinoatrial node pacemaker, through the atria, conducting structures and ventricular myocardium. These physiological events are driven by interacting, voltage-dependent, processes of activation, inactivation, and recovery in the ion channels present in cardiomyocyte membranes. Generation and conduction of these events are further modulated by intracellular Ca2+ homeostasis, and metabolic and structural change. This review describes experimental studies on murine models for known clinical arrhythmic conditions in which these mechanisms were modified by genetic, physiological, or pharmacological manipulation. These exemplars yielded molecular, physiological, and structural phenotypes often directly translatable to their corresponding clinical conditions, which could be investigated at the molecular, cellular, tissue, organ, and whole animal levels. Arrhythmogenesis could be explored during normal pacing activity, regular stimulation, following imposed extra-stimuli, or during progressively incremented steady pacing frequencies. Arrhythmic substrate was identified with temporal and spatial functional heterogeneities predisposing to reentrant excitation phenomena. These could arise from abnormalities in cardiac pacing function, tissue electrical connectivity, and cellular excitation and recovery. Triggering events during or following recovery from action potential excitation could thereby lead to sustained arrhythmia. These surface membrane processes were modified by alterations in cellular Ca2+ homeostasis and energetics, as well as cellular and tissue structural change. Study of murine systems thus offers major insights into both our understanding of normal cardiac activity and its propagation, and their relationship to mechanisms generating clinical arrhythmias.
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Affiliation(s)
- Christopher L-H Huang
- Physiological Laboratory and the Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
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19
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Abstract
Despite the epidemiological scale of atrial fibrillation, current treatment strategies are of limited efficacy and safety. Ideally, novel drugs should specifically correct the pathophysiological mechanisms responsible for atrial fibrillation with no other cardiac or extracardiac actions. Atrial-selective drugs are directed toward cellular targets with sufficiently different characteristics in atria and ventricles to modify only atrial function. Several potassium (K+) channels with either predominant expression in atria or distinct electrophysiological properties in atria and ventricles can serve as atrial-selective drug targets. These channels include the ultra-rapidly activating, delayed outward-rectifying Kv1.5 channel conducting IKur, the acetylcholine-activated inward-rectifying Kir3.1/Kir3.4 channel conducting IK,ACh, the Ca2+-activated K+ channels of small conductance (SK) conducting ISK, and the two pore domain K+ (K2P) channels TWIK-1, TASK-1 and TASK-3 that are responsible for voltage-independent background currents ITWIK-1, ITASK-1, and ITASK-3. Here, we briefly review the characteristics of these K+ channels and their roles in atrial fibrillation. The antiarrhythmic potential of drugs targeting the described channels is discussed as well as their putative value in treatment of atrial fibrillation.
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Affiliation(s)
- Ursula Ravens
- Institute of Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Freiburg, Germany; Department of Cardiology and Angiology I, University Heart Center Freiburg-Bad Krozingen, Freiburg, Germany; Department of Physiology, Medical Faculty Carl-Gustav-Carus, TU Dresden, Dresden, Germany.
| | - Katja E Odening
- Institute of Experimental Cardiovascular Medicine, University Heart Center Freiburg-Bad Krozingen, Freiburg, Germany; Department of Cardiology and Angiology I, University Heart Center Freiburg-Bad Krozingen, Freiburg, Germany
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20
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Calcium Handling Abnormalities as a Target for Atrial Fibrillation Therapeutics: How Close to Clinical Implementation? J Cardiovasc Pharmacol 2016; 66:515-22. [PMID: 25830486 DOI: 10.1097/fjc.0000000000000253] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Atrial fibrillation (AF) is the most common cardiac arrhythmia with a substantial impact on morbidity and mortality. Antiarrhythmic drugs play a major role in rhythm-control therapy of AF. However, currently available agents exhibit limited efficacy and pronounced adverse effects, notably drug-induced proarrhythmia. Recent experimental studies have identified that Ca handling abnormalities are critical elements in AF pathophysiology with central roles in atrial ectopic activity, reentry, and atrial remodeling suggesting that Ca handling abnormalities could be promising targets for novel AF therapeutics. Here, we summarize key aspects of AF-related Ca-handling abnormalities, describe currently available compounds targeting atrial Ca handling, and highlight potential novel targets and experimental drugs currently under investigation. Finally, we assess how close AF therapeutics based on Ca-handling abnormalities are to clinical implementation.
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21
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Christ T, Kovács PP, Acsai K, Knaut M, Eschenhagen T, Jost N, Varró A, Wettwer E, Ravens U. Block of Na(+)/Ca(2+) exchanger by SEA0400 in human right atrial preparations from patients in sinus rhythm and in atrial fibrillation. Eur J Pharmacol 2016; 788:286-293. [PMID: 27373849 DOI: 10.1016/j.ejphar.2016.06.050] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 06/17/2016] [Accepted: 06/28/2016] [Indexed: 01/10/2023]
Abstract
The Na(+)/Ca(2+) exchanger (NCX) plays a major role in myocardial Ca(2+) homoeostasis, but is also considered to contribute to the electrical instability and contractile dysfunction in chronic atrial fibrillation (AF). Here we have investigated the effects of the selective NCX blocker SEA0400 in human right atrial cardiomyocytes from patients in sinus rhythm (SR) and AF in order to obtain electrophysiological evidence for putative antiarrhythmic activity of this new class of drugs. Action potentials were measured in right atrial trabeculae using conventional microelectrodes. Human myocytes were enzymatically isolated. Rat atrial and ventricular cardiomyocytes were used for comparison. Using perforated-patch, NCX was measured as Ni(2+)-sensitive current during ramp pulses. In ruptured-patch experiments, NCX current was activated by changing the extracellular Ca(2+) concentration from 0 to 1mM in Na(+)-free bath solution (100mM Na(+) intracellular, "Hilgemann protocol"). Although SEA0400 was effective in rat cardiomyocytes, 10µM did not influence action potentials and contractility, neither in SR nor AF. SEA0400 (10μM) also failed to affect human atrial NCX current measured with perforated patch. With the "Hilgemann protocol" SEA0400 concentration-dependently suppressed human atrial NCX current, and its amplitude was larger in AF than in SR cardiomyocytes. Our results confirm higher NCX activity in AF than SR. SEA0400 fails to block Ni(2+)-sensitive current in human atrial cells unless unphysiological conditions are used. We speculate that block of NCX with SEA0400 depends on intracellular Na(+) concentration.
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Affiliation(s)
- Torsten Christ
- Department of Pharmacology and Toxicology, Medical Faculty, TU Dresden, Fetscherstr. 74, d-01307 Dresden, Germany; Department of Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Peter P Kovács
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary.
| | - Karoly Acsai
- MTA-SZTE Cardiovascular Pharmacological Research Group, University of Szeged, Szeged, Hungary.
| | - Michael Knaut
- Clinic for Cardiac Surgery, Heart Center Dresden, Fetscherstrasse 76, 01307 Dresden, Germany.
| | - Thomas Eschenhagen
- Department of Pharmacology and Toxicology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
| | - Norbert Jost
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary; MTA-SZTE Cardiovascular Pharmacological Research Group, University of Szeged, Szeged, Hungary.
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary; MTA-SZTE Cardiovascular Pharmacological Research Group, University of Szeged, Szeged, Hungary.
| | - Erich Wettwer
- Department of Pharmacology and Toxicology, Medical Faculty, TU Dresden, Fetscherstr. 74, d-01307 Dresden, Germany.
| | - Ursula Ravens
- Department of Pharmacology and Toxicology, Medical Faculty, TU Dresden, Fetscherstr. 74, d-01307 Dresden, Germany.
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22
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Weber S, Meyer-Roxlau S, Wagner M, Dobrev D, El-Armouche A. Counteracting Protein Kinase Activity in the Heart: The Multiple Roles of Protein Phosphatases. Front Pharmacol 2015; 6:270. [PMID: 26617522 PMCID: PMC4643138 DOI: 10.3389/fphar.2015.00270] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 10/28/2015] [Indexed: 12/19/2022] Open
Abstract
Decades of cardiovascular research have shown that variable and flexible levels of protein phosphorylation are necessary to maintain cardiac function. A delicate balance between phosphorylated and dephosphorylated states of proteins is guaranteed by a complex interplay of protein kinases (PKs) and phosphatases. Serine/threonine phosphatases, in particular members of the protein phosphatase (PP) family govern dephosphorylation of the majority of these cardiac proteins. Recent findings have however shown that PPs do not only dephosphorylate previously phosphorylated proteins as a passive control mechanism but are capable to actively control PK activity via different direct and indirect signaling pathways. These control mechanisms can take place on (epi-)genetic, (post-)transcriptional, and (post-)translational levels. In addition PPs themselves are targets of a plethora of proteinaceous interaction partner regulating their endogenous activity, thus adding another level of complexity and feedback control toward this system. Finally, novel approaches are underway to achieve spatiotemporal pharmacologic control of PPs which in turn can be used to fine-tune misleaded PK activity in heart disease. Taken together, this review comprehensively summarizes the major aspects of PP-mediated PK regulation and discusses the subsequent consequences of deregulated PP activity for cardiovascular diseases in depth.
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Affiliation(s)
- Silvio Weber
- Department of Pharmacology and Toxicology, Dresden University of Technology , Dresden, Germany
| | - Stefanie Meyer-Roxlau
- Department of Pharmacology and Toxicology, Dresden University of Technology , Dresden, Germany
| | - Michael Wagner
- Department of Pharmacology and Toxicology, Dresden University of Technology , Dresden, Germany
| | - Dobromir Dobrev
- Institute of Pharmacology, Faculty of Medicine, West German Heart and Vascular Center , Essen, Germany
| | - Ali El-Armouche
- Department of Pharmacology and Toxicology, Dresden University of Technology , Dresden, Germany
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23
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24
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van Marion DMS, Lanters EAH, Wiersma M, Allessie MA, Brundel BBJJM, de Groot NMS. Diagnosis and Therapy of Atrial Fibrillation: The Past, The Present and The Future. J Atr Fibrillation 2015; 8:1216. [PMID: 27957185 DOI: 10.4022/jafib.1216] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 07/05/2015] [Accepted: 01/10/2015] [Indexed: 02/03/2023]
Abstract
Atrial fibrillation (AF) is the most common age-related cardiac arrhythmia. It is a progressive disease, which makes treatment difficult. The progression of AF is caused by the accumulation of damage in cardiomyocytes which makes the atria more vulnerable for AF. Especially structural remodeling and electrical remodeling, together called electropathology are sustainable in the atria and impair functional recovery to sinus rhythm after cardioversion. The exact electropathological mechanisms underlying persistence of AF are at present unknown. High resolution wavemapping studies in patients with different types of AF showed that longitudinal dissociation in conduction and epicardial breakthrough were the key elements of the substrate of longstanding persistent AF. A double layer of electrically dissociated waves propagating transmurally can explain persistence of AF (Double Layer Hypothesis) but the molecular mechanism is unknown. Derailment of proteasis -defined as the homeostasis in protein synthesis, folding, assembly, trafficking, guided by chaperones, and clearance by protein degradation systems - may play an important role in remodeling of the cardiomyocyte. As current therapies are not effective in attenuating AF progression, step-by-step analysis of this process, in order to identify potential targets for drug therapy, is essential. In addition, novel mapping approaches enabling assessment of the degree of electropathology in the individual patient are mandatory to develop patient-tailored therapies. The aims of this review are to 1) summarize current knowledge of the electrical and molecular mechanisms underlying AF 2) discuss the shortcomings of present diagnostic instruments and therapeutic options and 3) to present potential novel diagnostic tools and therapeutic targets.
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Affiliation(s)
- Denise M S van Marion
- Department of Clinical Pharmacy and Pharmacology, University Institute for Drug Exploration (GUIDE), University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Eva A H Lanters
- Department of Cardiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Marit Wiersma
- Department of Cardiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Maurits A Allessie
- Department of Clinical Pharmacy and Pharmacology, University Institute for Drug Exploration (GUIDE), University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Bianca B J J M Brundel
- Department of Clinical Pharmacy and Pharmacology, University Institute for Drug Exploration (GUIDE), University Medical Center Groningen, University of Groningen, Groningen, The Netherlands; Department of Clinical Pharmacy and Pharmacology, University Institute for Drug Exploration (GUIDE), University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Natasja M S de Groot
- Department of Clinical Pharmacy and Pharmacology, University Institute for Drug Exploration (GUIDE), University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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25
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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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26
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Ju YK, Lee BH, Trajanovska S, Hao G, Allen DG, Lei M, Cannell MB. The involvement of TRPC3 channels in sinoatrial arrhythmias. Front Physiol 2015; 6:86. [PMID: 25859221 PMCID: PMC4373262 DOI: 10.3389/fphys.2015.00086] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 03/04/2015] [Indexed: 01/08/2023] Open
Abstract
Atrial fibrillation (AF) is a significant contributor to cardiovascular morbidity and mortality. The currently available treatments are limited and AF continues to be a major clinical challenge. Clinical studies have shown that AF is frequently associated with dysfunction in the sino-atrial node (SAN). The association between AF and SAN dysfunction is probably related to the communication between the SAN and the surrounding atrial cells that form the SAN-atrial pacemaker complex and/or pathological processes that affect both the SAN and atrial simultaneously. Recent evidence suggests that Ca2+ entry through TRPC3 (Transient Receptor Potential Canonical-3) channels may underlie several pathophysiological conditions -including cardiac arrhythmias. However, it is still not known if atrial and sinoatrial node cells are also involved. In this article we will first briefly review TRPC3 and IP3R signaling that relate to store/receptor-operated Ca2+ entry (SOCE/ROCE) mechanisms and cardiac arrhythmias. We will then present some of our recent research progress in this field. Our experiments results suggest that pacing-induced AF in angiotensin II (Ang II) treated mice are significantly reduced in mice lacking the TRPC3 gene (TRPC3−/− mice) compared to wild type controls. We also show that pacemaker cells express TRPC3 and several other molecular components related to SOCE/ROCE signaling, including STIM1 and IP3R. Activation of G-protein coupled receptors (GPCRs) signaling that is able to modulate SOCE/ROCE and Ang II induced Ca2+ homeostasis changes in sinoatrial complex being linked to TRPC3. The results provide new evidence that TRPC3 may play a role in sinoatrial and atrial arrhythmias that are caused by GPCRs activation.
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Affiliation(s)
- Yue-Kun Ju
- Department of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney Sydney, NSW, Australia
| | - Bon Hyang Lee
- Department of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney Sydney, NSW, Australia
| | - Sofie Trajanovska
- Department of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney Sydney, NSW, Australia
| | - Gouliang Hao
- Department of Pharmacology, University of Oxford Oxford, UK
| | - David G Allen
- Department of Physiology, School of Medical Sciences, Bosch Institute, University of Sydney Sydney, NSW, Australia
| | - Ming Lei
- Department of Pharmacology, University of Oxford Oxford, UK
| | - Mark B Cannell
- Department of Physiology and Pharmacology, University of Bristol Bristol, UK
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27
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Gutbrod SR, Sulkin MS, Rogers JA, Efimov IR. Patient-specific flexible and stretchable devices for cardiac diagnostics and therapy. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 115:244-51. [PMID: 25106701 DOI: 10.1016/j.pbiomolbio.2014.07.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 07/24/2014] [Indexed: 11/30/2022]
Abstract
Advances in material science techniques and pioneering circuit designs have led to the development of electronic membranes that can form intimate contacts with biological tissues. In this review, we present the range of geometries, sensors, and actuators available for custom configurations of electronic membranes in cardiac applications. Additionally, we highlight the desirable mechanics achieved by such devices that allow the circuits and substrates to deform with the beating heart. These devices unlock opportunities to collect continuous data on the electrical, metabolic, and mechanical state of the heart as well as a platform on which to develop high definition therapeutics.
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Affiliation(s)
- Sarah R Gutbrod
- Biomedical Engineering, Washington University in St Louis, USA
| | | | - John A Rogers
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, USA
| | - Igor R Efimov
- Biomedical Engineering, Washington University in St Louis, USA.
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28
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Lin YK, Chen YC, Kao YH, Tsai CF, Yeh YH, Huang JL, Cheng CC, Chen SA, Chen YJ. A monounsaturated fatty acid (oleic acid) modulates electrical activity in atrial myocytes with calcium and sodium dysregulation. Int J Cardiol 2014; 176:191-8. [PMID: 25064200 DOI: 10.1016/j.ijcard.2014.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 05/07/2014] [Accepted: 07/05/2014] [Indexed: 01/05/2023]
Abstract
BACKGROUND Obesity and metabolic syndrome are important risk factors for atrial fibrillation. High plasma concentrations of monounsaturated fatty acids, including oleic acid (OLA), are frequently noted in obese individuals and patients with metabolic syndrome. However, it is not clear whether monounsaturated fatty acids (MUFAs) can directly modulate the electrophysiological characteristics of atrial myocytes. METHODS Whole-cell patch clamp, indo-1 fluorescence, and Western blot analyses were used to record the action potentials (APs), ionic currents, and protein expressions of HL-1 myocytes incubated with and without (control) OLA (0.5mM) for 24h. RESULTS Compared to control myocytes (n=14), OLA-treated myocytes (n=16) had shorter APD90 (65 ± 6 vs. 85 ± 6 ms, p<0.05) and APD50 (24 ± 6 vs. 38 ± 4 ms, p<0.05) with a higher incidence of delayed afterdepolarizations (35.7% vs. 7%, p<0.05), which were suppressed by 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS, a blocker of the calcium-activated chloride current). In addition, OLA-treated myocytes (n=19) exhibited larger calcium transients (0.54 ± 0.06 vs. 0.38 ± 0.05 R410/485, p<0.05), and sarcoplasmic reticular calcium contents (0.91 ± 0.05 vs. 0.64 ± 0.08 R410/485, p<0.05) than control myocytes (n=15). OLA-treated myocytes had larger late sodium currents, smaller sodium-calcium exchanger currents, and smaller sodium-potassium pump currents. Moreover OLA-treated myocytes had higher expressions of sarcoplasmic reticular Ca(2+)-ATPase and calmodulin kinase II, but lower expression of the sodium-potassium ATPase protein than control myocytes. CONCLUSIONS MUFAs can regulate atrial electrophysiological characteristics with calcium and sodium dysregulation, which may contribute to atrial arrhythmogenesis.
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Affiliation(s)
- Yung-Kuo Lin
- Division of Cardiovascular Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan; Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Yao-Chang Chen
- Department of Biomedical Engineering, National Defense Medical Center, Taipei, Taiwan
| | - Yu-Hsun Kao
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Medical Education and Research, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan
| | - Chin-Feng Tsai
- Division of Cardiology, Department of Internal Medicine, Chung Shan Medical University Hospital, Taichung, Taiwan; School of Medicine, Chung Shan Medical University, Taichung, Taiwan
| | - Yung-Hsin Yeh
- The First Cardiovascular Division, Chang-Gung Memorial Hospital, Chang-Gung University, Taoyuan, Taiwan
| | - Jin-Long Huang
- Cardiovascular Center, Taichung Veterans General Hospital, Taichung, Taiwan; Faculty of Medicine and Institute of Clinical Medicine, and Cardiovascular Research Institute, National Yang-Ming University, Taipei, Taiwan
| | | | - Shih-Ann Chen
- National Yang-Ming University, School of Medicine, Division of Cardiology and Cardiovascular Research Center, Veterans General Hospital-Taipei, Taipei, Taiwan
| | - Yi-Jen Chen
- Division of Cardiovascular Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan; Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
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Heijman J, Voigt N, Wehrens XHT, Dobrev D. Calcium dysregulation in atrial fibrillation: the role of CaMKII. Front Pharmacol 2014; 5:30. [PMID: 24624086 PMCID: PMC3940963 DOI: 10.3389/fphar.2014.00030] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 02/15/2014] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is the most frequently encountered clinical arrhythmia and is associated with increased morbidity and mortality. Ectopic activity and reentry are considered major arrhythmogenic mechanisms contributing to the initiation and maintenance of AF. In addition, AF is self-reinforcing through progressive electrical and structural remodeling which stabilize the arrhythmia and make it more difficult to treat. Recent research has suggested an important role for Ca(2+)-dysregulation in AF. Ca(2+)-handling abnormalities may promote ectopic activity, conduction abnormalities facilitating reentry, and AF-related remodeling. In this review article, we summarize the Ca(2+)-handling derangements occurring in AF and discuss their impact on fundamental arrhythmogenic mechanisms. We focus in particular on the role of the multifunctional Ca(2+)/calmodulin-dependent protein kinase type-II (CaMKII), which acts as a major link between Ca(2+)-dysregulation and arrhythmogenesis. CaMKII expression and activity are increased in AF and promote arrhythmogenesis through phosphorylation of various targets involved in cardiac electrophysiology and excitation-contraction coupling. We discuss the implications for potential novel therapeutic strategies for AF based on CaMKII and Ca(2+)-handling abnormalities.
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Affiliation(s)
- Jordi Heijman
- Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen Essen, Germany
| | - Niels Voigt
- Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen Essen, Germany
| | - Xander H T Wehrens
- Cardiovascular Research Institute, Departments of Molecular Physiology and Biophysics, and Medicine-Cardiology, Baylor College of Medicine Houston, TX, USA
| | - Dobromir Dobrev
- Institute of Pharmacology, Faculty of Medicine, University Duisburg-Essen Essen, Germany
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Abstract
MicroRNAs (miRNAs) are emerging as key control molecules in the regulation of gene expression, and their role in heart disease is becoming increasingly evident. Given the critical role of Ca
2+
handling and signaling proteins in the maintenance of cardiac function, the targeting of such proteins by miRNAs would be expected to have important consequences. miRNAs have indeed been shown to control the expression of genes encoding important Ca
2+
handling and signaling proteins, and are themselves regulated by Ca
2+
-dependent processes. Ca
2+
-related miRNAs have been found to be significant pathophysiological contributors in conditions like myocardial ischemic injury, cardiac hypertrophy, heart failure, ventricular arrhythmogenesis, and atrial fibrillation. This review is a comprehensive analysis of the present knowledge concerning miRNA regulation of Ca
2+
handling processes, the participation of Ca
2+
-regulating miRNAs in the evolution of heart disease, the mutual relationship between Ca
2+
signaling and miRNAs in the control of cardiac function, and the potential value of miRNA-control of Ca
2+
handling as a therapeutic target.
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Affiliation(s)
- Masahide Harada
- From the Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada (M.H., X.L., S.N.); Department of Cardiology, Hamamatsu Medical Center, Hamamatsu, Japan (M.H.); Cardiovascular Research Institute and Department of Pharmacology, Harbin Medical University, Harbin, People’s Republic of China (X.L.; B.Y.); Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan (T.M.); and Institute of Pharmacology, Faculty
| | - Xiaobin Luo
- From the Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada (M.H., X.L., S.N.); Department of Cardiology, Hamamatsu Medical Center, Hamamatsu, Japan (M.H.); Cardiovascular Research Institute and Department of Pharmacology, Harbin Medical University, Harbin, People’s Republic of China (X.L.; B.Y.); Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan (T.M.); and Institute of Pharmacology, Faculty
| | - Toyoaki Murohara
- From the Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada (M.H., X.L., S.N.); Department of Cardiology, Hamamatsu Medical Center, Hamamatsu, Japan (M.H.); Cardiovascular Research Institute and Department of Pharmacology, Harbin Medical University, Harbin, People’s Republic of China (X.L.; B.Y.); Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan (T.M.); and Institute of Pharmacology, Faculty
| | - Baofeng Yang
- From the Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada (M.H., X.L., S.N.); Department of Cardiology, Hamamatsu Medical Center, Hamamatsu, Japan (M.H.); Cardiovascular Research Institute and Department of Pharmacology, Harbin Medical University, Harbin, People’s Republic of China (X.L.; B.Y.); Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan (T.M.); and Institute of Pharmacology, Faculty
| | - Dobromir Dobrev
- From the Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada (M.H., X.L., S.N.); Department of Cardiology, Hamamatsu Medical Center, Hamamatsu, Japan (M.H.); Cardiovascular Research Institute and Department of Pharmacology, Harbin Medical University, Harbin, People’s Republic of China (X.L.; B.Y.); Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan (T.M.); and Institute of Pharmacology, Faculty
| | - Stanley Nattel
- From the Department of Medicine and Research Center, Montreal Heart Institute and Université de Montréal, Montreal, Quebec, Canada (M.H., X.L., S.N.); Department of Cardiology, Hamamatsu Medical Center, Hamamatsu, Japan (M.H.); Cardiovascular Research Institute and Department of Pharmacology, Harbin Medical University, Harbin, People’s Republic of China (X.L.; B.Y.); Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan (T.M.); and Institute of Pharmacology, Faculty
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31
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Hijazi Z, Siegbahn A, Andersson U, Granger CB, Alexander JH, Atar D, Gersh BJ, Mohan P, Harjola VP, Horowitz J, Husted S, Hylek EM, Lopes RD, McMurray JJV, Wallentin L. High-sensitivity troponin I for risk assessment in patients with atrial fibrillation: insights from the Apixaban for Reduction in Stroke and other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial. Circulation 2013; 129:625-34. [PMID: 24226808 DOI: 10.1161/circulationaha.113.006286] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND High-sensitivity troponin-I (hs-TnI) measurement improves risk assessment for cardiovascular events in many clinical settings, but the added value in atrial fibrillation patients has not been described. METHODS AND RESULTS At randomization, hs-TnI was analyzed in 14 821 atrial fibrillation patients in the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial comparing apixaban with warfarin. The associations between hs-TnI concentrations and clinical outcomes were evaluated by using adjusted Cox analysis. The hs-TnI assay detected troponin (≥1.3 ng/L) in 98.5% patients, 50% had levels >5.4, 25% had levels >10.1, and 9.2% had levels ≥23 ng/L (the 99th percentile in healthy individuals). During a median of 1.9 years follow-up, annual rates of stroke or systemic embolism ranged from 0.76% in the lowest hs-TnI quartile to 2.26% in the highest quartile (>10.1 ng/L). In multivariable analysis, hs-TnI was significantly associated with stroke or systemic embolism, adjusted hazard ratio 1.98 (1.42-2.78), P=0.0007. hs-TnI was also significantly associated with cardiac death; annual rates ranged from 0.40% to 4.24%, hazard ratio 4.52 (3.05-6.70), P<0.0001, in the corresponding groups, and for major bleeding hazard ratio 1.44 (1.11-1.86), P=0.0250. Adding hs-TnI levels to the CHA2DS2VASc score improved c-statistics from 0.629 to 0.653 for stroke or systemic embolism, and from 0.591 to 0.731 for cardiac death. There were no significant interactions with study treatment. CONCLUSIONS Troponin-I is detected in 98.5% and elevated in 9.2% of atrial fibrillation patients. The hs-TnI level is independently associated with a raised risk of stroke, cardiac death, and major bleeding and improves risk stratification beyond the CHA2DS2VASc score. The benefits of apixaban in comparison with warfarin are consistent regardless of hs-TnI levels. CLINICAL TRIAL REGISTRATION URL http://www.clinicaltrials.gov. Unique identifier: NCT00412984.
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Affiliation(s)
- Ziad Hijazi
- Uppsala Clinical Research Center, Uppsala University, Uppsala, Sweden (Z.H., A.S., U.A., L.W.); Department of Medical Sciences, Cardiology, Uppsala University, Uppsala, Sweden (Z.H., U.A., L.W.); Department of Medical Sciences, Clinical Chemistry, Uppsala University, Uppsala, Sweden (A.S.); Duke University, Medical Center, Durham, NC (C.B.G., J.H.A., R.D.L.); Department of Cardiology, Oslo University Hospital and Faculty of Medicine, Institute for Clinical Medicine, University of Oslo, Oslo, Norway (D.A.); Mayo Clinic College of Medicine, Rochester, MN (B.J.G.); Bristol-Myers Squibb, Princeton, NJ (P.M.); Division of Emergency Care, Department of Medicine, Helsinki University Central Hospital, Helsinki, Finland (V.-P.H.); University of Adelaide, Adelaide, Australia (J.H.); Medical Department, Hospital Unit West, Herning/Holstbro, Denmark (S.H.); Boston University Medical Center, Boston, MA (E.M.H.); and BHF Cardiovascular Research Centre, University of Glasgow, Glasgow, Scotland, United Kingdom (J.J.V.M.)
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Kornej J, Husser D, Bollmann A, Lip GYH. Rhythm outcomes after catheter ablation of atrial fibrillation. Clinical implication of biomarkers. Hamostaseologie 2013; 34:9-19. [PMID: 24166596 DOI: 10.5482/hamo-13-09-0051] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 10/21/2013] [Indexed: 12/13/2022] Open
Abstract
Atrial fibrillation (AF) occurs as the result of numerous complex physiological processes in the atria leading to AF promotion and maintenance. Improved diagnostic techniques have identified various biomarkers which may play an important role in the prediction of AF related outcomes (cardio- and cerebrovascular events, as well as mortality and rhythm outcomes). Biomarkers refer to 'biological markers' and biomarkers in blood, urine as well as imaging marker (eg, dimensions (left atrial diameter and volume), anatomical features (left appendage and pulmonary vein anatomy), and physiological pattern (LAA flow velocity)) may play important role(s) as clinically important indices in relation to outcomes after different therapeutic strategies. However, the main domain in the biomarker field has focused on blood-based biomarkers, which are widely used to predict therapeutic success regarding underlying pathophysiological mechanism, such as inflammation, fibrosis, endothelial damage. This review provides an update of the role of clinically relevant biomarkers in AF, with particular focus on AF rhythm outcomes.
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Affiliation(s)
| | | | | | - G Y H Lip
- Prof. Gregory Y. H. Lip, Centre for Cardiovascular Sciences, University of Birmingham City Hospital, Birmingham, United Kingdom, E-mail:
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33
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Weeke P, Parvez B, Blair M, Short L, Ingram C, Kucera G, Stubblefield T, Roden DM, Darbar D. Candidate gene approach to identifying rare genetic variants associated with lone atrial fibrillation. Heart Rhythm 2013; 11:46-52. [PMID: 24120998 DOI: 10.1016/j.hrthm.2013.10.025] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Rare variants in candidate atrial fibrillation (AF) genes have been associated with AF in small kindreds. The extent to which such polymorphisms contribute to AF is unknown. OBJECTIVE The purpose of this study was to determine the spectrum and prevalence of rare amino acid coding (AAC) variants in candidate AF genes in a large cohort of unrelated lone AF probands. METHODS We resequenced 45 candidate genes in 303 European American (EA) lone AF probands (186 lone AF probands screened for each gene on average [range 89-303], 63 screened for all) identified in the Vanderbilt AF Registry (2002-2012). Variants detected were screened against 4300 EAs from the Exome Sequencing Project (ESP) to identify very rare (minor allele frequency ≤0.04%) AAC variants and these were tested for AF co-segregation in affected family members where possible. RESULTS Median age at AF onset was 46.0 years [interquartile range 33.0-54.0], and 35.6% had a family history of AF. Overall, 63 very rare AAC variants were identified in 60 of 303 lone AF probands, and 10 of 19 (52.6%) had evidence of co-segregation with AF. Among the 63 lone AF probands who had 45 genes screened, the very rare variant burden was 22%. Compared with the 4300 EA ESP, the proportion of lone AF probands with a very rare AAC variant in CASQ2 and NKX2-5 was increased 3-5-fold (P <.05). CONCLUSION No very rare AAC variants were identified in ~80% of lone AF probands. Potential reasons for the lack of very rare AAC variants include a complex pattern of inheritance, variants in as yet unidentified AF genes or in noncoding regions, and environmental factors.
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Affiliation(s)
- Peter Weeke
- Department of Medicine, Vanderbilt University, Nashville, Tennessee; Department of Cardiology, Copenhagen University Hospital, Gentofte, Denmark
| | - Babar Parvez
- Department of Medicine, Vanderbilt University, Nashville, Tennessee
| | - Marcia Blair
- Department of Medicine, Vanderbilt University, Nashville, Tennessee
| | - Laura Short
- Department of Medicine, Vanderbilt University, Nashville, Tennessee
| | - Christie Ingram
- Department of Medicine, Vanderbilt University, Nashville, Tennessee
| | - Gayle Kucera
- Department of Medicine, Vanderbilt University, Nashville, Tennessee
| | | | - Dan M Roden
- Departments of Medicine and Pharmacology, Vanderbilt University, Nashville, Tennessee
| | - Dawood Darbar
- Department of Medicine, Vanderbilt University, Nashville, Tennessee.
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Hijazi Z, Wallentin L, Siegbahn A, Andersson U, Alexander JH, Atar D, Gersh BJ, Hanna M, Harjola VP, Horowitz JD, Husted S, Hylek EM, Lopes RD, McMurray JJV, Granger CB. High-sensitivity troponin T and risk stratification in patients with atrial fibrillation during treatment with apixaban or warfarin. J Am Coll Cardiol 2013; 63:52-61. [PMID: 24055845 DOI: 10.1016/j.jacc.2013.07.093] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 07/06/2013] [Accepted: 07/23/2013] [Indexed: 12/11/2022]
Abstract
OBJECTIVES The aim of this study was to evaluate the prognostic value of high-sensitivity troponin T (hs-TnT) in addition to clinical risk factors and the CHA2DS2VASc (congestive heart failure, hypertension, 75 years of age and older, diabetes mellitus, previous stroke or transient ischemic attack, vascular disease, 65 to 74 years of age, female) risk score in patients with atrial fibrillation (AF). BACKGROUND The level of troponin is a powerful predictor of cardiovascular events and mortality. METHODS A total of 14,897 patients with AF were randomized to treatment with apixaban or warfarin in the ARISTOTLE (Apixaban for the Prevention of Stroke in Subjects With Atrial Fibrillation) trial. The associations between baseline hs-TnT levels and outcomes were evaluated using adjusted Cox regression models. RESULTS Levels of hs-TnT were measurable in 93.5% of patients; 75% had levels >7.5 ng/l, 50% had levels >11.0 ng/l, and 25% had levels >16.7 ng/l. During a median 1.9-year period, the annual rates of stroke or systemic embolism ranged from 0.87% in the lowest hs-TnT quartile to 2.13% in the highest hs-TnT quartile (adjusted hazard ratio [HR]: 1.94; 95% confidence interval [CI]: 1.35 to 2.78; p = 0.0010). The annual rates in the corresponding groups ranged from 0.46% to 4.24% (adjusted HR: 4.31; 95% CI: 2.91 to 6.37; p < 0.0001) for cardiac death and from 1.26% to 4.21% (adjusted HR: 1.91; 95% CI: 1.43 to 2.56; p = 0.0001) for major bleeding. Adding hs-TnT levels to the CHA2DS2VASc score improved the C statistic from 0.620 to 0.635 for stroke or systemic embolism (p = 0.0226), from 0.592 to 0.711 for cardiac death (p < 0.0001), and from 0.591 to 0.629 for major bleeding (p < 0.0001). Apixaban reduced rates of stroke, mortality, and bleeding regardless of the hs-TnT level. CONCLUSIONS Levels of hs-TnT are often elevated in patients with AF. The hs-TnT level is independently associated with an increased risk of stroke, cardiac death, and major bleeding and improves risk stratification beyond the CHA2DS2VASc risk score. The benefits of apixaban as compared with warfarin are consistent regardless of the hs-TnT level. (Apixaban for the Prevention of Stroke in Subjects With Atrial Fibrillation [ARISTOTLE]; NCT00412984).
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Affiliation(s)
- Ziad Hijazi
- Uppsala Clinical Research Center, Uppsala University, Uppsala, Sweden; Section of Cardiology, Department of Medical Sciences, Uppsala University, Uppsala, Sweden.
| | - Lars Wallentin
- Uppsala Clinical Research Center, Uppsala University, Uppsala, Sweden; Section of Cardiology, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Agneta Siegbahn
- Uppsala Clinical Research Center, Uppsala University, Uppsala, Sweden; Section of Clinical Chemistry, Department of Medical Sciences, Uppsala University, Uppsala, Sweden
| | - Ulrika Andersson
- Uppsala Clinical Research Center, Uppsala University, Uppsala, Sweden
| | - John H Alexander
- Duke Clinical Research Institute, Duke University Medical Center, Durham, North Carolina
| | - Dan Atar
- Department of Cardiology, Oslo University Hospital Ulleval and Faculty of Medicine, Institute for Clinical Medicine, University of Oslo, Oslo, Norway
| | | | | | - Veli Pekka Harjola
- Division of Emergency Care, Department of Medicine, Helsinki University Central Hospital, Helsinki, Finland
| | - John D Horowitz
- University of Adelaide, Adelaide, South Australia, Australia
| | - Steen Husted
- Medical Department, Hospital Unit West, Herning/Holstbro, Denmark
| | | | - Renato D Lopes
- Duke Clinical Research Institute, Duke University Medical Center, Durham, North Carolina
| | - John J V McMurray
- BHF Cardiovascular Research Centre, University of Glasgow, Glasgow, Scotland, United Kingdom
| | - Christopher B Granger
- Duke Clinical Research Institute, Duke University Medical Center, Durham, North Carolina
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King JH, Wickramarachchi C, Kua K, Du Y, Jeevaratnam K, Matthews HR, Grace AA, Huang CLH, Fraser JA. Loss of Nav1.5 expression and function in murine atria containing the RyR2-P2328S gain-of-function mutation. Cardiovasc Res 2013; 99:751-9. [PMID: 23723061 DOI: 10.1093/cvr/cvt141] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
AIMS Recent studies reported slowed conduction velocity (CV) in murine hearts homozygous for the gain-of-function RyR2-P2328S mutation (RyR2(S/S)) and associated this with an increased incidence of atrial and ventricular arrhythmias. The present experiments determined mechanisms contributing to the reduced atrial CV. METHODS AND RESULTS The determinants of CV were investigated in murine RyR2(S/S) hearts and compared with those in wild-type (WT) and slow-conducting Scn5a(+/-) hearts. Picrosirius red staining demonstrated increased fibrosis only in Scn5a(+/-) hearts. Immunoblot assays showed similar expressions of Cx43 and Cx40 levels in the three genotypes. In contrast, Nav1.5 expression was reduced in both RyR2(S/S) and Scn5a(+/-) atria. These findings correlated with intracellular microelectrode and loose-patch-clamp studies. Microelectrode measurements showed reduced maximum rates of depolarization in Scn5a(+/-) and RyR2(S/S) atria compared with WT, despite similar diastolic membrane potentials. Loose-patch-clamp measurements demonstrated reduced peak Na(+) currents (INa) in the Scn5a(+/-) and RyR2(S/S) atria relative to WT, with similar normalized current-voltage relationships. In WT atria, reduction in INa could be produced by treatment with high extracellular Ca(2+), caffeine, or cyclopiazonic acid, each expected to produce an acute increase in [Ca(2+)]i. CONCLUSION RyR2(S/S) atria show reduced levels of Nav1.5 expression and Na(+) channel function. Reduced Na(+) channel function was also observed in WT atria, following acute increases in [Ca(2+)]i. Taken together, the results suggest that raised [Ca(2+)]i produces both acute and chronic inhibition of Na(+) channel function. These findings may help explain the relationship between altered Ca(2+) homeostasis, CV, and the maintenance of common arrhythmias such as atrial fibrillation.
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Affiliation(s)
- James H King
- Physiological Laboratory, University of Cambridge, UK
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36
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Zhang Y, Matthews GDK, Lei M, Huang CLH. Abnormal Ca(2+) homeostasis, atrial arrhythmogenesis, and sinus node dysfunction in murine hearts modeling RyR2 modification. Front Physiol 2013; 4:150. [PMID: 23805105 PMCID: PMC3691467 DOI: 10.3389/fphys.2013.00150] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Accepted: 06/05/2013] [Indexed: 12/19/2022] Open
Abstract
Ryanodine receptor type 2 (RyR2) mutations are implicated in catecholaminergic polymorphic ventricular tachycardia (CPVT) thought to result from altered myocyte Ca(2+) homeostasis reflecting inappropriate "leakiness" of RyR2-Ca(2+) release channels arising from increases in their basal activity, alterations in their phosphorylation, or defective interactions with other molecules or ions. The latter include calstabin, calsequestrin-2, Mg(2+), and extraluminal or intraluminal Ca(2+). Recent clinical studies additionally associate RyR2 abnormalities with atrial arrhythmias including atrial tachycardia (AT), fibrillation (AF), and standstill, and sinus node dysfunction (SND). Some RyR2 mutations associated with CPVT in mouse models also show such arrhythmias that similarly correlate with altered Ca(2+) homeostasis. Some examples show evidence for increased Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) phosphorylation of RyR2. A homozygotic RyR2-P2328S variant demonstrates potential arrhythmic substrate resulting from reduced conduction velocity (CV) in addition to delayed afterdepolarizations (DADs) and ectopic action potential (AP) firing. Finally, one model with an increased RyR2 activity in the sino-atrial node (SAN) shows decreased automaticity in the presence of Ca(2+)-dependent decreases in I Ca, L and diastolic sarcoplasmic reticular (SR) Ca(2+) depletion.
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Affiliation(s)
- Yanmin Zhang
- Department of Paediatrics, Institute of Shaanxi Province Children's Cardiovascular Diseases, The Shaanxi Provincial People's Hospital of Xi'an Jiaotong UniversityXi'an, PR of China
- Faculty of Medicine and Human Sciences, Institute of Cardiovascular Sciences, University of ManchesterManchester, UK
| | | | - Ming Lei
- Faculty of Medicine and Human Sciences, Institute of Cardiovascular Sciences, University of ManchesterManchester, UK
| | - Christopher L.-H. Huang
- Physiological Laboratory, Faculty of Biology, University of CambridgeCambridge, UK
- Department of Biochemistry, University of CambridgeCambridge, UK
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37
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Greiser M, Schotten U. Dynamic remodeling of intracellular Ca2+ signaling during atrial fibrillation. J Mol Cell Cardiol 2013; 58:134-42. [DOI: 10.1016/j.yjmcc.2012.12.020] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2012] [Revised: 12/14/2012] [Accepted: 12/17/2012] [Indexed: 12/23/2022]
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Voigt N, Dobrev D. Cellular and molecular correlates of ectopic activity in patients with atrial fibrillation. Europace 2013; 14 Suppl 5:v97-v105. [PMID: 23104921 DOI: 10.1093/europace/eus282] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Atrial fibrillation (AF) is the most frequent arrhythmia and is associated with increased morbidity and mortality. Current drugs for AF treatment have limited efficacy and a substantial risk of proarrhythmic side effects, making novel drug development critical. Emerging evidence suggests that abnormal intracellular calcium (Ca(2+)) signalling is a key contributor to ectopic (triggered) electrical activity in human AF. Accordingly, atrial Ca(2+)-handling abnormalities underlying ectopic activity may constitute novel mechanism-based therapeutic approaches to treat AF. This article reviews the recent evidence for a role of cellular ectopic activity in human AF pathophysiology, discusses the molecular mechanisms underlying triggered activity in human atrial myocytes, and considers their relevance to the design of novel therapeutic options.
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Affiliation(s)
- Niels Voigt
- Division of Experimental Cardiology, Medical Faculty Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, Mannheim, Germany
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39
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Hijazi Z, Oldgren J, Siegbahn A, Granger CB, Wallentin L. Biomarkers in atrial fibrillation: a clinical review. Eur Heart J 2013; 34:1475-80. [PMID: 23386711 DOI: 10.1093/eurheartj/eht024] [Citation(s) in RCA: 204] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Assessment of atrial fibrillation (AF)-associated stroke risk is at present mainly based on clinical risk scores such as CHADS2 and CHA2DS2-VASc, although these scores provide only modest discrimination of risk for individual patients. Biomarkers derived from the blood may help refine risk assessment in AF for stroke outcomes and for mortality. Recent studies of biomarkers in AF have shown that they can substantially improve risk stratification. Cardiac biomarkers, such as troponin and natriuretic peptides, significantly improve risk stratification in addition to current clinical risk stratification models. Similar findings have recently been described for markers of renal function, coagulation, and inflammation in AF populations based on large randomized prospective clinical trials or large community-based cohorts. These new findings may enable development of novel tools to improve clinical risk assessment in AF. Biomarkers in AF may also improve the understanding of the pathophysiology of AF further as well as potentially elucidate novel treatment targets. This review will highlight novel associations of biomarkers and outcomes in AF as well as recent progress in the use of biomarkers for risk stratification.
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Affiliation(s)
- Ziad Hijazi
- Uppsala Clinical Research Center (UCR), Uppsala University, Uppsala Science Park, Uppsala, Sweden.
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40
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Heijman J, Voigt N, Nattel S, Dobrev D. Calcium handling and atrial fibrillation. Wien Med Wochenschr 2013; 162:287-91. [PMID: 22695810 DOI: 10.1007/s10354-012-0109-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Atrial fibrillation (AF) is the most prevalent sustained cardiac arrhythmia in the clinical setting. It is associated with substantial cardiovascular morbidity and mortality. Recent research has indicated that abnormal Ca(2+) handling plays a critical role in the induction and maintenance of AF, contributing to ectopic activity, AF-maintaining reentry circuits and related prothrombotic atrial hypocontractility. The AF-specific Ca(2+)-handling abnormalities may constitute viable therapeutic approaches to treat AF. Here, we review the causes, consequences, and therapeutic implications of altered atrial Ca(2+) handling for AF pathophysiology.
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Affiliation(s)
- Jordi Heijman
- Division of Experimental Cardiology, Medical Faculty Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
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King JH, Zhang Y, Lei M, Grace AA, Huang CLH, Fraser JA. Atrial arrhythmia, triggering events and conduction abnormalities in isolated murine RyR2-P2328S hearts. Acta Physiol (Oxf) 2013; 207:308-23. [PMID: 22958452 DOI: 10.1111/apha.12006] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 08/15/2012] [Accepted: 09/03/2012] [Indexed: 12/19/2022]
Abstract
AIM RyR2 mutations are associated with catecholaminergic polymorphic tachycardia, a condition characterized by ventricular and atrial arrhythmias. The present experiments investigate the atrial electrophysiology of homozygotic murine RyR2-P2328S (RyR2(S/S)) hearts for ectopic triggering events and for conduction abnormalities that might provide a re-entrant substrate. METHODS Electrocardiograph recordings were made from regularly stimulated RyR2(S/S) and wild type (WT) hearts, perfused using a novel modified Langendorff preparation. This permitted the simultaneous use of either floating intracellular microelectrodes to measure action potential (AP) parameters, or a multielectrode array to measure epicardial conduction velocity (CV). RESULTS RyR2(S/S) showed frequent sustained tachyarrhythmias, delayed afterdepolarizations and ectopic APs, increased interatrial conduction delays, reduced epicardial CVs and reduced maximum rates of AP depolarization ((dV/dt)(max)), despite similar effective refractory periods, AP durations and AP amplitudes. Effective interatrial CVs and (dV/dt)(max) values of APs following ectopic (S2) stimulation were lower than those of APs following regular stimulation and decreased with shortening S1S2 intervals. However, although RyR2(S/S) atria showed arrhythmias over a wider range of S1S2 intervals, the interatrial CV and (dV/dt)(max) of S2 APs provoking such arrhythmias were similar in RyR2(S/S) and WT. CONCLUSIONS These results suggest that abnormal intracellular Ca(2+) homoeostasis produces both arrhythmic triggers and a slow-conducting arrhythmic substrate in RyR2(S/S) atria. A similar mechanism might also contribute to arrhythmogenesis in other conditions, associated with diastolic Ca(2+) release, such as atrial fibrillation.
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Affiliation(s)
- J. H. King
- Physiological Laboratory; University of Cambridge; Cambridge; UK
| | - Y. Zhang
- Physiological Laboratory; University of Cambridge; Cambridge; UK
| | - M. Lei
- Institute of Cardiovascular Sciences; University of Manchester; Manchester; UK
| | - A. A. Grace
- Department of Biochemistry; University of Cambridge; Cambridge; UK
| | | | - J. A. Fraser
- Physiological Laboratory; University of Cambridge; Cambridge; UK
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Otani N, Matsuda R, Oda K, Nishino S, Inoue T, Kaneko N. Protective effect of K201 on isoproterenol-induced and ischemic-reperfusion-induced ventricular arrhythmias in the rat: comparison with diltiazem. J Cardiovasc Pharmacol Ther 2012; 18:184-90. [PMID: 23144205 DOI: 10.1177/1074248412465489] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
AIM Ventricular arrhythmia (VA) is a risk for sudden death. Polymorphic ventricular tachycardia (VT) degenerating to ventricular fibrillation occurs subsequent to the prolongation of the QT interval following administration of catecholamines under Ca(2+) loading. Fatal VA also occurs in ischemia and ischemic-reperfusion. We compared the suppressive effect of K201 (JTV519), a multiple-channel blocker and cardiac ryanodine receptor-calcium release channel (RyR2) stabilizer, with that of diltiazem, a Ca(2+ )channel blocker, in 2 studies of isoproterenol-induced (n = 30) and ischemic-reperfusion-induced VAs (n = 38) in rats. METHODS Adult male Wistar rats were administered 12 mg/kg/min calcium chloride (CaCl(2)) for 20 minutes and then 6 μg/kg/min isoproterenol was infused with CaCl(2) for a further 20 minutes. In other rats, the left coronary artery was ligated for 5 minutes followed by reperfusion for 20 minutes. K201 or diltiazem (both 1 mg/kg) was administered before infusion of the isoproterenol or induction of ischemia. RESULTS After administration of isoproterenol under Ca(2+) loading, fatal VA frequently occurred in the vehicle (9 of 10 animals, 90%) and diltiazem (8 of 10, 80%) groups, and K201 significantly suppressed the incidences of arrhythmia and mortality (2 of 10, 20%). In the reperfusion study, the incidence and the time until occurrence of reperfusion-induced VA and mortality were significantly suppressed in the K201 (2 of 15 animals, 13%) and diltiazem (1 of 9 animals, 11%) groups compared to the vehicle group (8 of 14 animals, 57%). SIGNIFICANCE Induction of VA in an experimental model was achieved with a low dose of isoproterenol under Ca(2+) loading. K201 markedly suppressed both the isoproterenol-induced and the reperfusion-induced VAs, whereas diltiazem did not suppress the isoproterenol-induced VA. The results suggest that both VAs are related to early after depolarization (EAD) and indicate that K201 has the potential to suppress EAD by stabilizing RyR2 to mediate Ca(2+) release from the sarcoplasmic reticulum and acting as a multiple-channel blocker.
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Affiliation(s)
- Naoyuki Otani
- Department of Cardiovascular Medicine, Dokkyo Medical University, Kitakobayashi, Tochigi, Japan
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Backx PH. Could Plugging the Oxidation-Mediated Ca
2+
Leak Stem the Tide of the Atrial Fibrillation Epidemic? Circ Res 2012; 111:662-5. [DOI: 10.1161/circresaha.112.275453] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Thul R, Coombes S, Bootman MD. Persistence of pro-arrhythmic spatio-temporal calcium patterns in atrial myocytes: a computational study of ping waves. Front Physiol 2012; 3:279. [PMID: 22934033 PMCID: PMC3429053 DOI: 10.3389/fphys.2012.00279] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 06/28/2012] [Indexed: 11/13/2022] Open
Abstract
Clusters of ryanodine receptors within atrial myocytes are confined to spatially separated layers. In many species, these layers are not juxtaposed by invaginations of the plasma membrane (transverse tubules; 'T-tubules'), so that calcium-induced-calcium signals rely on centripetal propagation rather than voltage-synchronized channel openings to invade the interior of the cell and trigger contraction. The combination of this specific cellular geometry and dynamics of calcium release can lead to novel autonomous spatio-temporal calcium waves, and in particular ping waves. These are waves of calcium release activity that spread as counter-rotating sectors of elevated calcium within a single layer of ryanodine receptors, and can seed further longitudinal calcium waves. Here we show, using a computational model, that these calcium waves can dominate the response of a cell to electrical pacing and hence are pro-arrhythmic. This highlights the importance of modeling internal cellular structures when investigating mechanisms of cardiac dysfunction such as atrial arrhythmia.
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Affiliation(s)
- Rüdiger Thul
- School of Mathematical Sciences, University of Nottingham Nottingham, UK
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45
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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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Xie LH, Shanmugam M, Park JY, Zhao Z, Wen H, Tian B, Periasamy M, Babu GJ. Ablation of sarcolipin results in atrial remodeling. Am J Physiol Cell Physiol 2012; 302:C1762-71. [PMID: 22496245 DOI: 10.1152/ajpcell.00425.2011] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Sarcolipin (SLN) is a key regulator of sarco(endo)plasmic reticulum (SR) Ca(2+)-ATPase (SERCA), and its expression is altered in diseased atrial myocardium. To determine the precise role of SLN in atrial Ca(2+) homeostasis, we developed a SLN knockout (sln-/-) mouse model and demonstrated that ablation of SLN enhances atrial SERCA pump activity. The present study is designed to determine the long-term effects of enhanced SERCA activity on atrial remodeling in the sln-/- mice. Calcium transient measurements show an increase in atrial SR Ca(2+) load and twitch Ca(2+) transients. Patch-clamping experiments demonstrate activation of the forward mode of sodium/calcium exchanger, increased L-type Ca(2+) channel activity, and prolongation of action potential duration at 90% repolarization in the atrial myocytes of sln-/- mice. Spontaneous Ca(2+) waves, delayed afterdepolarization, and triggered activities are frequent in the atrial myocytes of sln-/- mice. Furthermore, loss of SLN in atria is associated with increased interstitial fibrosis and altered expression of genes encoding collagen and other extracellular matrix proteins. Our results also show that the sln-/- mice are susceptible to atrial arrhythmias upon aging. Together, these findings indicate that ablation of SLN results in increased SERCA activity and SR Ca(2+) load, which, in turn, could cause abnormal intracellular Ca(2+) handling and atrial remodeling.
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Affiliation(s)
- Lai-Hua Xie
- Department of Cell Biology and Molecular Medicine, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, 07103, USA
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Abstract
Atrial fibrillation is the most common type of cardiac arrhythmia, and is responsible for substantial morbidity and mortality in the general population. Current treatments have moderate efficacy and considerable risks, especially of pro-arrhythmia, highlighting the need for new therapeutic strategies. In recent years, substantial efforts have been invested in developing novel treatments that target the underlying molecular determinants of atrial fibrillation, and several new compounds are under development. This Review focuses on the mechanistic rationale for the development of new anti-atrial fibrillation drugs, on the molecular and structural motifs that they target and on the results obtained so far in experimental and clinical studies.
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48
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Voigt N, Li N, Wang Q, Wang W, Trafford AW, Abu-Taha I, Sun Q, Wieland T, Ravens U, Nattel S, Wehrens XHT, Dobrev D. Enhanced sarcoplasmic reticulum Ca2+ leak and increased Na+-Ca2+ exchanger function underlie delayed afterdepolarizations in patients with chronic atrial fibrillation. Circulation 2012; 125:2059-70. [PMID: 22456474 DOI: 10.1161/circulationaha.111.067306] [Citation(s) in RCA: 465] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Delayed afterdepolarizations (DADs) carried by Na(+)-Ca(2+)-exchange current (I(NCX)) in response to sarcoplasmic reticulum (SR) Ca(2+) leak can promote atrial fibrillation (AF). The mechanisms leading to delayed afterdepolarizations in AF patients have not been defined. METHODS AND RESULTS Protein levels (Western blot), membrane currents and action potentials (patch clamp), and [Ca(2+)](i) (Fluo-3) were measured in right atrial samples from 76 sinus rhythm (control) and 72 chronic AF (cAF) patients. Diastolic [Ca(2+)](i) and SR Ca(2+) content (integrated I(NCX) during caffeine-induced Ca(2+) transient) were unchanged, whereas diastolic SR Ca(2+) leak, estimated by blocking ryanodine receptors (RyR2) with tetracaine, was ≈50% higher in cAF versus control. Single-channel recordings from atrial RyR2 reconstituted into lipid bilayers revealed enhanced open probability in cAF samples, providing a molecular basis for increased SR Ca(2+) leak. Calmodulin expression (60%), Ca(2+)/calmodulin-dependent protein kinase-II (CaMKII) autophosphorylation at Thr287 (87%), and RyR2 phosphorylation at Ser2808 (protein kinase A/CaMKII site, 236%) and Ser2814 (CaMKII site, 77%) were increased in cAF. The selective CaMKII blocker KN-93 decreased SR Ca(2+) leak, the frequency of spontaneous Ca(2+) release events, and RyR2 open probability in cAF, whereas protein kinase A inhibition with H-89 was ineffective. Knock-in mice with constitutively phosphorylated RyR2 at Ser2814 showed a higher incidence of Ca(2+) sparks and increased susceptibility to pacing-induced AF compared with controls. The relationship between [Ca(2+)](i) and I(NCX) density revealed I(NCX) upregulation in cAF. Spontaneous Ca(2+) release events accompanied by inward I(NCX) currents and delayed afterdepolarizations/triggered activity occurred more often and the sensitivity of resting membrane voltage to elevated [Ca(2+)](i) (diastolic [Ca(2+)](i)-voltage coupling gain) was higher in cAF compared with control. CONCLUSIONS Enhanced SR Ca(2+) leak through CaMKII-hyperphosphorylated RyR2, in combination with larger I(NCX) for a given SR Ca(2+) release and increased diastolic [Ca(2+)](i)-voltage coupling gain, causes AF-promoting atrial delayed afterdepolarizations/triggered activity in cAF patients.
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Affiliation(s)
- Niels Voigt
- Division of Experimental Cardiology, Medical Faculty Mannheim, University of Heidelberg, Germany
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Meijering RAM, Zhang D, Hoogstra-Berends F, Henning RH, Brundel BJJM. Loss of proteostatic control as a substrate for atrial fibrillation: a novel target for upstream therapy by heat shock proteins. Front Physiol 2012; 3:36. [PMID: 22375124 PMCID: PMC3284689 DOI: 10.3389/fphys.2012.00036] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2011] [Accepted: 02/09/2012] [Indexed: 12/19/2022] Open
Abstract
Atrial fibrillation (AF) is the most common, sustained clinical tachyarrhythmia associated with significant morbidity and mortality. AF is a persistent condition with progressive structural remodeling of the atrial cardiomyocytes due to the AF itself, resulting in cellular changes commonly observed in aging and in other heart diseases. While rhythm control by electrocardioversion or drug treatment is the treatment of choice in symptomatic AF patients, its efficacy is still limited. Current research is directed at preventing first-onset AF by limiting the development of substrates underlying AF progression and resembles mechanism-based therapy. Upstream therapy refers to the use of non-ion channel anti-arrhythmic drugs that modify the atrial substrate- or target-specific mechanisms of AF, with the ultimate aim to prevent the occurrence (primary prevention) or recurrence of the arrhythmia following (spontaneous) conversion (secondary prevention). Heat shock proteins (HSPs) are molecular chaperones and comprise a large family of proteins involved in the protection against various forms of cellular stress. Their classical function is the conservation of proteostasis via prevention of toxic protein aggregation by binding to (partially) unfolded proteins. Our recent data reveal that HSPs prevent electrical, contractile, and structural remodeling of cardiomyocytes, thus attenuating the AF substrate in cellular, Drosophila melanogaster, and animal experimental models. Furthermore, studies in humans suggest a protective role for HSPs against the progression from paroxysmal AF to persistent AF and in recurrence of AF. In this review, we discuss upregulation of the heat shock response system as a novel target for upstream therapy to prevent derailment of proteostasis and consequently progression and recurrence of AF.
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Affiliation(s)
- Roelien A M Meijering
- Department of Clinical Pharmacology, Groningen University Institute for Drug Exploration, University Medical Center Groningen, University of Groningen Groningen, Netherlands
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50
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Collins TP, Terrar DA. Ca(2+)-stimulated adenylyl cyclases regulate the L-type Ca(2+) current in guinea-pig atrial myocytes. J Physiol 2012; 590:1881-93. [PMID: 22351635 DOI: 10.1113/jphysiol.2011.227066] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Ca(2+)-stimulated adenylyl cyclases (ACs) have recently been shown to play important roles in pacemaking in the sino-atrial node. Here we present evidence that Ca(2+)-stimulated ACs are functionally active in guinea-pig atrial myocytes. Basal activity of an AC in isolated atrial myocytes was demonstrated by the observations that MDL 12,330A (10 μm), an AC inhibitor, reduced L-type Ca(2+) current (I(CaL)) amplitude, while inhibition of phosphodiesterases with IBMX (100 μm) increased I(CaL) amplitude. Buffering of cytosolic Ca(2+) by exposure of myocytes to BAPTA-AM (5 μm) reduced I(CaL) amplitude, as did inhibition of Ca(2+) release from the sarcoplasmic reticulum with ryanodine (2 μm) and thapsigargin (1 μm). [Ca(2+)]i-activated calmodulin kinase II (CaMKII) inhibition with KN-93 (1 μm) reduced I(CaL), but subsequent application of BAPTA-AM further reduced I(CaL). This effect of BAPTA-AM, in the presence of CaMKII inhibition, demonstrates that there is an additional Ca(2+)-modulated pathway (not dependent on CaMKII) that regulates I(CaL) in atrial myocytes. The effects of BAPTA could be reversed by forskolin (10 μm), a direct stimulator of all AC isoforms, which would restore cAMP levels. In the presence of BAPTA-AM, the actions of IBMX were reduced. In addition, inclusion of cAMP in the patch electrode in the whole-cell configuration prevented the effects of BAPTA. These effects are all consistent with a role for Ca(2+)-stimulated AC in the regulation of atrial myocyte I(CaL).
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Affiliation(s)
- Thomas P Collins
- National Heart and Lung Institute, Imperial College, Guy Scadding Building, Dovehouse Street, London SW3 6LY, UK.
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