Wen Hairuo, Zhao Zhenghang, Fefelova Nadezhda, Xie Lai-Hua
Department of Cell Biology and Molecular Medicine, Rutgers New Jersey Medical School, Newark, NJ, United States.
Key Laboratory of Beijing for Nonclinical Safety Evaluation Research of Drugs, National Center for Safety Evaluation of Drugs, National Institutes for Food and Drug Control, Beijing, China.
Front Physiol. 2018 Dec 13;9:1785. doi: 10.3389/fphys.2018.01785. eCollection 2018.
Store-operated calcium entry (SOCE) is an important physiological phenomenon that extensively mediates intracellular calcium ion (Ca) load. It has been previously found in myocytes isolated from neonatal or diseased hearts. We aimed to determine its existence, molecular nature in undiseased hearts and its potential arrhythmogenic implications under hyperactive conditions. Ventricular myocytes isolated from adult FVB mice were studied by using Ca imaging and whole-cell perforated patch-clamp recording. In addition, lead II ECGs were recorded in isolated Langendorff-perfused mice hearts. Functional TRPC channel antibodies and inhibitors, and TRPC6 activator hyperforin were used. In this study, we demonstrate the existence and contribution of SOCE in normal adult mouse cardiac myocytes. For an apparent SOCE activation, complete depletion of sarcoplasmic reticulum (SR) Ca by employing both caffeine (10 mM) and thapsigargin (1 μM) or cyclopiazonic acid (10 μM) was required. Consistent with the notion that SOCE may be mediated by heteromultimeric TRPC channels, SOCEs observed from those myocytes were significantly reduced by the pretreatment with anti-TRPC1, 3, and 6 antibodies as well as by gadolinium, a non-selective TRPC channel blocker. In addition, we showed that SOCE may regulate spontaneous SR Ca release, Ca waves, and triggered activities which may manifest cardiac arrhythmias. Since the spontaneous depolarization in membrane potential preceded the elevation of intracellular Ca, an inward membrane current presumably via TRPC channels was considered as the predominant cause of cellular arrhythmias. The selective TRPC6 activator hyperforin (0.1-10 μM) significantly facilitated the SOCE, SOCE-mediated inward current, and calcium load in the ventricular myocytes. ECG recording further demonstrated the proarrhythmic effects of hyperforin in mouse hearts. We suggest that SOCE, which is at least partially mediated by TRPC channels, exists in adult mouse ventricular myocytes. TRPC channels and SOCE mechanism may be involved in cardiac arrhythmogenesis via promotion of spontaneous Ca waves and triggered activities under hyperactivated conditions.
钙库操纵性钙内流（SOCE）是一种重要的生理现象，广泛介导细胞内钙离子（Ca）负载。此前已在从新生或患病心脏分离的心肌细胞中发现该现象。我们旨在确定其在未患病心脏中的存在、分子性质及其在过度活跃条件下的潜在致心律失常影响。通过使用钙成像和全细胞穿孔膜片钳记录对从成年FVB小鼠分离的心室肌细胞进行了研究。此外，在离体Langendorff灌注的小鼠心脏中记录了II导联心电图。使用了功能性瞬时受体电位通道（TRPC）抗体和抑制剂，以及TRPC6激活剂贯叶连翘素。在本研究中，我们证明了SOCE在正常成年小鼠心肌细胞中的存在及其作用。为了实现明显的SOCE激活，需要使用咖啡因（10 mM）和毒胡萝卜素（1 μM）或环匹阿尼酸（10 μM）完全耗尽肌浆网（SR）中的钙。与SOCE可能由异源多聚体TRPC通道介导的观点一致, 用抗TRPC1、3和6抗体以及非选择性TRPC通道阻滞剂钆预处理后，从这些心肌细胞中观察到的SOCE显著降低。此外，我们表明SOCE可能调节自发SR钙释放、钙波和触发活动，这些可能表现为心律失常。由于膜电位的自发去极化先于细胞内钙的升高，推测通过TRPC通道的内向膜电流被认为是细胞心律失常的主要原因。选择性TRPC6激活剂贯叶连翘素（0.1 - 10 μM）显著促进了心室肌细胞中的SOCE、SOCE介导的内向电流和钙负载。心电图记录进一步证明了贯叶连翘素对小鼠心脏的促心律失常作用。我们认为，至少部分由TRPC通道介导的SOCE存在于成年小鼠心室肌细胞中。TRPC通道和SOCE机制可能通过在过度激活条件下促进自发钙波和触发活动而参与心脏心律失常的发生。
