Uncovering the arrhythmogenic potential of TRPM4 activation in atrial-derived HL-1 cells using novel recording and numerical approaches
Uncovering the arrhythmogenic potential of TRPM4 activation in atrial-derived HL-1 cells using novel recording and numerical approaches
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DOI：
10.1093/cvr/cvx117
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发表时间：
2017-08-01
影响因子：
10.8
通讯作者：
Inoue, Ryuji
中科院分区：
文献类型：
--
作者：
Hu, Yaopeng;Duan, Yubin;Inoue, Ryuji
目的 瞬时受体电位阳离子通道亚家族M型成员4（TRPM4）是一种在心脏中大量表达的钙激活非选择性阳离子通道，与心脏重构和损伤相关的传导阻滞及其他心律失常倾向有关。本研究旨在定量评估TRPM4的致心律失常潜能。
方法与结果 使用表达系统和永生化心房心肌细胞系（HL - 1）进行膜片钳和生化分析，并采用数值模型模拟。在快速脱敏后，TRPM4通道的强烈再激活需要高微摩尔浓度的Ca²⁺。然而，通过一种新设计的离子霉素透化细胞贴附（Iono - C/A）记录技术评估，亚微摩尔浓度的Ca²⁺（表观Kd≈500 nM）足以激活该通道。在尖锐电极全细胞记录以及共表达TRPM4和L型电压依赖性Ca²⁺通道的实验中也观察到了类似的亚微摩尔Ca²⁺依赖性。使用多个动作电位（AP）模型（HL - 1、尼格伦、罗 - 鲁迪）进行数值模拟，这些模型纳入了通过Iono - C/A记录评估的TRPM4的钙和电压依赖性门控参数，结果表明TRPM4活性增加几倍足以延迟动作电位晚期复极化，进一步增加（≥6倍）则会诱发早期后除极。这些模型预测与血管紧张素II处理的HL - 1细胞的电生理数据一致，在这些细胞中TRPM4的表达和活性增强。
结论 这些结果共同表明TRPM4通道可被生理浓度范围的Ca²⁺激活，其过度活动可导致心律失常变化。此外，这些结果证明了首个纳入TRPM4门控的动作电位模型在计算机模拟评估心脏重构组织致心律失常性方面的潜在用途。
Aims Transient receptor potential cation channel subfamily melastatin member 4 (TRPM4), a Ca2+-activated nonselective cation channel abundantly expressed in the heart, has been implicated in conduction block and other arrhythmic propensities associated with cardiac remodelling and injury. The present study aimed to quantitatively evaluate the arrhythmogenic potential of TRPM4.Methods and results Patch clamp and biochemical analyses were performed using expression system and an immortalized atrial cardiomyocyte cell line (HL-1), and numerical model simulation was employed. After rapid desensitization, robust reactivation of TRPM4 channels required high micromolar concentrations of Ca2+. However, upon evaluation with a newly devised, ionomycin-permeabilized cell-attached (Iono-C/A) recording technique, submicromolar concentrations of Ca2+ (apparent K-d = similar to 500 nM) were enough to activate this channel. Similar submicromolar Ca2+ dependency was also observed with sharp electrode whole-cell recording and in experiments coexpressing TRPM4 and L-type voltage-dependent Ca2+ channels. Numerical simulations using a number of action potential (AP) models (HL-1, Nygren, Luo-Rudy) incorporating the Ca2+-and voltage-dependent gating parameters of TRPM4, as assessed by Iono-C/A recording, indicated that a few-fold increase in TRPM4 activity is sufficient to delay late AP repolarization and further increases (>= six-fold) evoke early afterdepolarization. These model predictions are consistent with electrophysiological data from angiotensin II-treated HL-1 cells in which TRPM4 expression and activity were enhanced.Conclusions These results collectively indicate that the TRPM4 channel is activated by a physiological range of Ca2+ concentrations and its excessive activity can cause arrhythmic changes. Moreover, these results demonstrate potential utility of the first AP models incorporating TRPM4 gating for in silico assessment of arrhythmogenicity in remodelling cardiac tissue.