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Owusu-Mensah A, Treat J, Bernardi J, Pfeiffer R, Goodrow R, Tsevi B, Lam V, Audette M, Cordeiro JM, Deo M. Identification and characterization of two novel KCNH2 mutations contributing to long QT syndrome. PLoS One 2024; 19:e0287206. [PMID: 38181028 PMCID: PMC10769013 DOI: 10.1371/journal.pone.0287206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 05/31/2023] [Indexed: 01/07/2024] Open
Abstract
We identified two different inherited mutations in KCNH2 gene, or human ether-a-go-go related gene (hERG), which are linked to Long QT Syndrome. The first mutation was in a 1-day-old infant, whereas the second was in a 14-year-old girl. The two KCNH2 mutations were transiently transfected into either human embryonic kidney (HEK) cells or human induced pluripotent stem-cell derived cardiomyocytes. We performed associated multiscale computer simulations to elucidate the arrhythmogenic potentials of the KCNH2 mutations. Genetic screening of the first and second index patients revealed a heterozygous missense mutation in KCNH2, resulting in an amino acid change (P632L) in the outer loop of the channel and substitution at position 428 from serine to proline (S428P), respectively. Heterologous expression of P632L and S428P into HEK cells produced no hERG current compared to the wild type (WT). Moreover, the co-transfection of WT and P632L yielded no hERG current; however, the co-transfection of WT and S428P yielded partial hERG current. Action potentials were prolonged in a complete or partial blockade of hERG current from computer simulations which was more severe in Purkinje than ventricular myocytes. Three dimensional simulations revealed a higher susceptibility to reentry in the presence of hERG current blockade. Our experimental findings suggest that both P632L and S428P mutations may impair the KCNH2 gene. The Purkinje cells exhibit a more severe phenotype than ventricular myocytes, and the hERG current blockade renders the ventricles an arrhythmogenic substrate from computer modeling.
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Affiliation(s)
- Anthony Owusu-Mensah
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia, United States of America
| | - Jacqueline Treat
- Masonic Medical Research Laboratory, Utica, New York, United States of America
| | - Joyce Bernardi
- Masonic Medical Research Laboratory, Utica, New York, United States of America
| | - Ryan Pfeiffer
- Masonic Medical Research Laboratory, Utica, New York, United States of America
| | - Robert Goodrow
- Masonic Medical Research Laboratory, Utica, New York, United States of America
| | - Bright Tsevi
- Department of Engineering, Norfolk State University, Norfolk, Virginia, United States of America
| | - Victoria Lam
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, Virginia, United States of America
| | - Michel Audette
- Department of Computational Modeling and Simulation Engineering, Old Dominion University, Norfolk, Virginia, United States of America
| | - Jonathan M. Cordeiro
- Masonic Medical Research Laboratory, Utica, New York, United States of America
- ICON Laboratory Services Incorporation, Whitesboro, New York, United States of America
| | - Makarand Deo
- Department of Engineering, Norfolk State University, Norfolk, Virginia, United States of America
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Yang J, Ye K, Zhang R, Fan X, Xiong R, Zhang S, Liu Q, Lin M, Wang B, Tan X, Wen Q, Ou X. The characteristics and molecular targets of antiarrhythmic natural products. Biomed Pharmacother 2023; 168:115762. [PMID: 37897974 DOI: 10.1016/j.biopha.2023.115762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 10/11/2023] [Accepted: 10/17/2023] [Indexed: 10/30/2023] Open
Abstract
Arrhythmia is one of the most common cardiovascular diseases. The search for new drugs to suppress various types of cardiac arrhythmias has always been the focus of attention. In the past decade, the screening of antiarrhythmic active substances from plants has received extensive attention. These natural compounds have obvious antiarrhythmic effects, and chemical modifications based on natural compounds have greatly increased their pharmacological properties. The chemical modification of botanical antiarrhythmic drugs is closely related to the development of new and promising drugs. Therefore, the structural characteristics and action targets of natural compounds with antiarrhythmic effects are reviewed in this paper, so that pharmacologists can select antiarrhythmic lead compounds from natural compounds based on the disease target - chemical structural characteristics.
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Affiliation(s)
- Jun Yang
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China; Department of Pharmacy, Santai County People's Hospital of Sichuan Province, Mianyang 621100, China
| | - Kejun Ye
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China; Pharmacy Department, Chongqing Armed Police Corps Hospital, Chongqing 400061, China
| | - Rui Zhang
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China
| | - Xinrong Fan
- The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Rui Xiong
- Department of Pharmacy of the 958 Hospital of Chinese PLA/Jiangbei Campus, The First Affiliated Hospital of Army Medical University, Chongqing 400020, China
| | - Shiyu Zhang
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China
| | - Qiming Liu
- School of Basic Medical Sciences, Southwest Medical University, Luzhou 646000, China
| | - Miao Lin
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China
| | - Bin Wang
- The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Xiaoqiu Tan
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China; School of Basic Medical Sciences, Southwest Medical University, Luzhou 646000, China.
| | - Qiang Wen
- Department of Cardiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Xianhong Ou
- Key Laboratory of Medical Electrophysiology of Ministry of Education and Medical Electrophysiological Key Laboratory of Sichuan Province, Institute of Cardiovascular Research, Southwest Medical University, Luzhou 646000, China; State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources, Guangxi Normal University, Guilin 541004, Guangxi Province, China.
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3
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MacDonnell S, Megna J, Ruan Q, Zhu O, Halasz G, Jasewicz D, Powers K, E H, del Pilar Molina-Portela M, Jin X, Zhang D, Torello J, Feric NT, Graziano MP, Shekhar A, Dunn ME, Glass D, Morton L. Activin A directly impairs human cardiomyocyte contractile function indicating a potential role in heart failure development. Front Cardiovasc Med 2022; 9:1038114. [PMID: 36440002 PMCID: PMC9685658 DOI: 10.3389/fcvm.2022.1038114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 10/10/2022] [Indexed: 09/27/2023] Open
Abstract
Activin A has been linked to cardiac dysfunction in aging and disease, with elevated circulating levels found in patients with hypertension, atherosclerosis, and heart failure. Here, we investigated whether Activin A directly impairs cardiomyocyte (CM) contractile function and kinetics utilizing cell, tissue, and animal models. Hydrodynamic gene delivery-mediated overexpression of Activin A in wild-type mice was sufficient to impair cardiac function, and resulted in increased cardiac stress markers (N-terminal pro-atrial natriuretic peptide) and cardiac atrophy. In human-induced pluripotent stem cell-derived (hiPSC) CMs, Activin A caused increased phosphorylation of SMAD2/3 and significantly upregulated SERPINE1 and FSTL3 (markers of SMAD2/3 activation and activin signaling, respectively). Activin A signaling in hiPSC-CMs resulted in impaired contractility, prolonged relaxation kinetics, and spontaneous beating in a dose-dependent manner. To identify the cardiac cellular source of Activin A, inflammatory cytokines were applied to human cardiac fibroblasts. Interleukin -1β induced a strong upregulation of Activin A. Mechanistically, we observed that Activin A-treated hiPSC-CMs exhibited impaired diastolic calcium handling with reduced expression of calcium regulatory genes (SERCA2, RYR2, CACNB2). Importantly, when Activin A was inhibited with an anti-Activin A antibody, maladaptive calcium handling and CM contractile dysfunction were abrogated. Therefore, inflammatory cytokines may play a key role by acting on cardiac fibroblasts, causing local upregulation of Activin A that directly acts on CMs to impair contractility. These findings demonstrate that Activin A acts directly on CMs, which may contribute to the cardiac dysfunction seen in aging populations and in patients with heart failure.
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Affiliation(s)
| | - Jake Megna
- Regeneron Pharmaceuticals, Tarrytown, NY, United States
| | - Qin Ruan
- Regeneron Pharmaceuticals, Tarrytown, NY, United States
| | - Olivia Zhu
- Regeneron Pharmaceuticals, Tarrytown, NY, United States
| | - Gabor Halasz
- Regeneron Pharmaceuticals, Tarrytown, NY, United States
| | - Dan Jasewicz
- Regeneron Pharmaceuticals, Tarrytown, NY, United States
| | - Kristi Powers
- Regeneron Pharmaceuticals, Tarrytown, NY, United States
| | - Hock E
- Regeneron Pharmaceuticals, Tarrytown, NY, United States
| | | | - Ximei Jin
- Regeneron Pharmaceuticals, Tarrytown, NY, United States
| | - Dongqin Zhang
- Regeneron Pharmaceuticals, Tarrytown, NY, United States
| | | | - Nicole T. Feric
- TARA Biosystems Inc., Alexandria Center for Life Sciences, New York, NY, United States
| | - Michael P. Graziano
- TARA Biosystems Inc., Alexandria Center for Life Sciences, New York, NY, United States
| | | | | | - David Glass
- Regeneron Pharmaceuticals, Tarrytown, NY, United States
| | - Lori Morton
- Regeneron Pharmaceuticals, Tarrytown, NY, United States
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Kalinowski J, Huang Y, Rivas MA, Barcelona V, Wright ML, Crusto C, Spruill T, Sun YV, Taylor JY. Stress Overload and DNA Methylation in African American Women in the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure Study. Epigenet Insights 2022; 15:25168657221126314. [PMID: 36246163 PMCID: PMC9554129 DOI: 10.1177/25168657221126314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 08/28/2022] [Indexed: 11/07/2022] Open
Abstract
Introduction: Experiencing psychosocial stress is associated with poor health outcomes such as hypertension and obesity, which are risk factors for developing cardiovascular disease. African American women experience disproportionate risk for cardiovascular disease including exposure to high levels of psychosocial stress. We hypothesized that psychosocial stress, such as perceived stress overload, may influence epigenetic marks, specifically DNA methylation (DNAm), that contribute to increased risk for cardiovascular disease in African American women. Methods: We conducted an epigenome-wide study evaluating the relationship of psychosocial stress and DNAm among African American mothers from the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure (InterGEN) cohort. Linear mixed effects models were used to explore the epigenome-wide associations with the Stress Overload Scale (SOS), which examines self-reported past-week stress, event load and personal vulnerability. Results: In total, n = 228 participants were included in our analysis. After adjusting for known epigenetic confounders, we did not identify any DNAm sites associated with maternal report of stress measured by SOS after controlling for multiple comparisons. Several of the top differentially methylated CpG sites related to SOS score (P < 1 × 10−5), mapped to genes of unknown significance for hypertension or heart disease, namely, PXDNL and C22orf42. Conclusions: This study provides foundational knowledge for future studies examining epigenetic associations with stress and other psychosocial measures in African Americans, a key area for growth in epigenetics. Future studies including larger sample sizes and replication data are warranted.
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Affiliation(s)
- Jolaade Kalinowski
- Department of Human Development and Family Sciences, The University of Connecticut, Storrs, CT, USA,Jolaade Kalinowski, Department of Human Development and Family Sciences, The University of Connecticut, 2006 Hillside Rd, Storrs, CT 06279-1248, USA.
| | - Yunfeng Huang
- Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Martin A Rivas
- Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Veronica Barcelona
- Columbia University School of Nursing and Center for Research on People of Color, New York, NY, USA
| | | | | | - Tanya Spruill
- Department of Population Health, NYU Grossman School of Medicine, New York, NY, USA
| | - Yan V Sun
- Rollins School of Public Health, Emory University, Atlanta, GA, USA
| | - Jacquelyn Y Taylor
- Columbia University School of Nursing and Center for Research on People of Color, New York, NY, USA
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Treat JA, Pfeiffer R, Barajas-Martinez H, Goodrow RJ, Bot C, Haedo RJ, Knox R, Cordeiro JM. Overlap Arrhythmia Syndromes Resulting from Multiple Genetic Variations Studied in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes. Int J Mol Sci 2021; 22:7108. [PMID: 34281161 PMCID: PMC8268422 DOI: 10.3390/ijms22137108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 06/07/2021] [Accepted: 06/24/2021] [Indexed: 11/16/2022] Open
Abstract
Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are used for genetic models of cardiac diseases. We report an arrhythmia syndrome consisting of Early Repolarization Syndrome (ERS) and Short QT Syndrome (SQTS). The index patient (MMRL1215) developed arrhythmia-mediated syncope after electrocution and was found to carry six mutations. Functional alterations resulting from these mutations were examined in patient-derived hiPSC-CMs. Electrophysiological recordings were made in hiPSC-CMs from MMRL1215 and healthy controls. ECG analysis of the index patient showed slurring of the QRS complex and QTc = 326 ms. Action potential (AP) recordings from MMRL1215 myocytes showed slower spontaneous activity and AP duration was shorter. Field potential recordings from MMRL1215 hiPSC-CMs lack a "pseudo" QRS complex suggesting reduced inward current(s). Voltage clamp analysis of ICa showed no difference in the magnitude of current. Measurements of INa reveal a 60% reduction in INa density in MMRL1215 hiPSC-CMs. Steady inactivation and recovery of INa was unaffected. mRNA analysis revealed ANK2 and SCN5A are significantly reduced in hiPSC-CM derived from MMRL1215, consistent with electrophysiological recordings. The polygenic cause of ERS/SQTS phenotype is likely due to a loss of INa due to a mutation in PKP2 coupled with and a gain of function in IK,ATP due to a mutation in ABCC9.
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Affiliation(s)
- Jacqueline A. Treat
- Department of Experimental Cardiology, Masonic Medical Research Institute, Utica, NY 13501, USA; (J.A.T.); (R.P.); (R.J.G.)
| | - Ryan Pfeiffer
- Department of Experimental Cardiology, Masonic Medical Research Institute, Utica, NY 13501, USA; (J.A.T.); (R.P.); (R.J.G.)
| | - Hector Barajas-Martinez
- Department of Cardiovascular Research, Lankenau Institute for Medical Research, Wynnewood, PA 19096, USA;
| | - Robert J. Goodrow
- Department of Experimental Cardiology, Masonic Medical Research Institute, Utica, NY 13501, USA; (J.A.T.); (R.P.); (R.J.G.)
| | - Corina Bot
- Nanion Technologies, 1 Naylon Ave. Suite C, Livingston, NJ 07039, USA; (C.B.); (R.J.H.); (R.K.)
| | - Rodolfo J. Haedo
- Nanion Technologies, 1 Naylon Ave. Suite C, Livingston, NJ 07039, USA; (C.B.); (R.J.H.); (R.K.)
| | - Ronald Knox
- Nanion Technologies, 1 Naylon Ave. Suite C, Livingston, NJ 07039, USA; (C.B.); (R.J.H.); (R.K.)
| | - Jonathan M. Cordeiro
- Department of Experimental Cardiology, Masonic Medical Research Institute, Utica, NY 13501, USA; (J.A.T.); (R.P.); (R.J.G.)
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Chen X, Barajas-Martínez H, Xia H, Zhang Z, Chen G, Yang B, Jiang H, Antzelevitch C, Hu D. Clinical and Functional Genetic Characterization of the Role of Cardiac Calcium Channel Variants in the Early Repolarization Syndrome. Front Cardiovasc Med 2021; 8:680819. [PMID: 34222376 PMCID: PMC8249565 DOI: 10.3389/fcvm.2021.680819] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Accepted: 04/20/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Early repolarization syndrome (ERS) is an inherited sudden cardiac death (SCD) syndrome. The present study investigates the role of genetic variants in cardiac calcium-channel genes in the pathogenesis of ERS and probes the underlying mechanisms. Methods: Polymerase chain reaction-based next-generation sequencing was carried out using a targeted gene approach. Unrelated ERS probands carrying calcium-channel variants were evaluated clinically and compared with matched healthy controls. Wild-type (WT) and mutant CACNA1C genes were coexpressed with CACNB2b and CACNA2D1 in HEK293 cells and studied using whole-cell patch-clamp techniques and confocal fluorescence microscope. Results: Among 104 ERS probands, 16 carried pathogenic variants in calcium-channel genes (32.2 ± 14.6 years old, 87.5% male). The symptoms at diagnosis included syncope (56.3%), ventricular tachycardia/fibrillation (62.5%), and SCD (56.3%). Three cases (18.8%) had a family history of SCD or syncope. Eight patients (50.0%) had a single calcium gene rare variant. The other half carried rare variants in other ERS-susceptible genes. Compared with controls, the heart rate was slower (72.7 ± 8.9 vs. 65.6 ± 16.1 beats/min, * p < 0.05), QTc interval was shorter (408.2 ± 21.4 vs. 386.8 ± 16.9 ms, ** p < 0.01), and Tp-e/QT was longer (0.22 ± 0.05 vs. 0.28 ± 0.04, *** p < 0.001) in single calcium mutation carriers. Electrophysiological analysis of one mutation, CACNA1C-P817S (c.2449C>T), revealed that the density of whole-cell calcium current (I Ca) was reduced by ~84.61% compared to WT (-3.17 ± 2.53 vs. -20.59 ± 3.60 pA/pF, n = 11 and 15, respectively, ** p < 0.01). Heterozygous expression of mutant channels was associated with a 51.35% reduction of I Ca. Steady-state inactivation was shifted to more negative potentials and significantly accelerated as well. Confocal microscopy revealed trafficking impairment of CACNA1C-P817S (peripheral/central intensity: 0.94 ± 0.10 in WT vs. 0.33 ± 0.12 in P817S, n = 10 and 9, respectively, ** p < 0.01). Conclusions: ERS associated with loss-of-function (LOF) genetic defects in genes encoding the cardiac calcium channel represents a unique clinical entity characterized by decreased heart rate and QTc, as well as increased transmural dispersion of repolarization. In the case of CACNA1C-P817S, impaired trafficking of the channel to the membrane contributes to the LOF.
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Affiliation(s)
- Xiu Chen
- Department of Cardiology and Cardiovascular Research Institute, Renmin Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Hector Barajas-Martínez
- Lankenau Institute for Medical Research, Lankenau Heart Institute, Wynnewood, PA, United States
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, United States
| | - Hao Xia
- Department of Cardiology and Cardiovascular Research Institute, Renmin Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Zhonghe Zhang
- Department of Cardiology and Cardiovascular Research Institute, Renmin Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Ganxiao Chen
- Department of Cardiology and Cardiovascular Research Institute, Renmin Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Bo Yang
- Department of Cardiology and Cardiovascular Research Institute, Renmin Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Hong Jiang
- Department of Cardiology and Cardiovascular Research Institute, Renmin Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Cardiology, Wuhan, China
| | - Charles Antzelevitch
- Lankenau Institute for Medical Research, Lankenau Heart Institute, Wynnewood, PA, United States
- Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, United States
| | - Dan Hu
- Department of Cardiology and Cardiovascular Research Institute, Renmin Hospital of Wuhan University, Wuhan, China
- Hubei Key Laboratory of Cardiology, Wuhan, China
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Abstract
Inherited cardiac arrhythmias contribute substantially to sudden cardiac death in the young. The underlying pathophysiology remains incompletely understood because of the lack of representative study models and the labour-intensive nature of electrophysiological patch clamp experiments. Whereas patch clamp is still considered the gold standard for investigating electrical properties in a cell, optical mapping of voltage and calcium transients has paved the way for high-throughput studies. Moreover, the development of human-induced pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs) has enabled the study of patient specific cell lines capturing the full genomic background. Nevertheless, hiPSC-CMs do not fully address the complex interactions between various cell types in the heart. Studies using in vivo models, are therefore necessary. Given the analogies between the human and zebrafish cardiovascular system, zebrafish has emerged as a cost-efficient model for arrhythmogenic diseases. In this review, we describe how hiPSC-CM and zebrafish are employed as models to study primary electrical disorders. We provide an overview of the contemporary electrophysiological phenotyping tools and discuss in more depth the different strategies available for optical mapping. We consider the current advantages and disadvantages of both hiPSC-CM and zebrafish as a model and optical mapping as phenotyping tool and propose strategies for further improvement. Overall, the combination of experimental readouts at cellular (hiPSC-CM) and whole organ (zebrafish) level can raise our understanding of the complexity of inherited cardiac arrhythmia disorders to the next level.
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Acacetin suppresses the electrocardiographic and arrhythmic manifestations of the J wave syndromes. PLoS One 2020; 15:e0242747. [PMID: 33232375 PMCID: PMC7685455 DOI: 10.1371/journal.pone.0242747] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 11/06/2020] [Indexed: 02/07/2023] Open
Abstract
Background J wave syndromes (JWS), including Brugada (BrS) and early repolarization syndromes (ERS), are associated with increased risk for life-threatening ventricular arrhythmias. Pharmacologic approaches to therapy are currently very limited. Here, we evaluate the effects of the natural flavone acacetin. Methods The effects of acacetin on action potential (AP) morphology and transient outward current (Ito) were first studied in isolated canine RV epicardial myocytes using whole-cell patch clamp techniques. Acacetin’s effects on transmembrane APs, unipolar electrograms and transmural ECGs were then studied in isolated coronary-perfused canine RV and LV wedge preparations as well as in whole-heart, Langendorff-perfused preparations from which we recorded a 12 lead ECG and unipolar electrograms. Using floating glass microelectrodes we also recorded transmembrane APs from the RVOT of the whole-heart model. The Ito agonist NS5806, sodium channel blocker ajmaline, calcium channel blocker verapamil or hypothermia (32°C) were used to pharmacologically mimic the genetic defects and conditions associated with JWS, thus eliciting prominent J waves and provoking VT/VF. Results Acacetin (5–10 μM) reduced Ito density, AP notch and J wave area and totally suppressed the electrocardiographic and arrhythmic manifestation of both BrS and ERS, regardless of the experimental model used. In wedge and whole-heart models of JWS, increasing Ito with NS5806, decreasing INa or ICa (with ajmaline or verapamil) or hypothermia all resulted in accentuation of epicardial AP notch and ECG J waves, resulting in characteristic BrS and ERS phenotypes. Phase 2-reentrant extrasystoles originating from the RVOT triggered VT/VF. The J waves in leads V1 and V2 were never associated with a delay of RVOT activation and always coincided with the appearance of the AP notch recorded from RVOT epicardium. All repolarization defects giving rise to VT/VF in the BrS and ERS models were reversed by acacetin, resulting in total suppression of VT/VF. Conclusions We present experimental models of BrS and ERS capable of recapitulating all of the ECG and arrhythmic manifestations of the JWS. Our findings provide definitive support for the repolarization but not the depolarization hypothesis proposed to underlie BrS and point to acacetin as a promising new pharmacologic treatment for JWS.
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