Role of inositol 1,4,5-trisphosphate in the regulation of ventricular Ca2+ signaling in intact mouse heart
Role of inositol 1,4,5-trisphosphate in the regulation of ventricular Ca2+ signaling in intact mouse heart
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DOI：
10.1016/j.yjmcc.2012.08.019
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发表时间：
2012-12-01
影响因子：
5
通讯作者：
Ramos-Franco, Josefina
中科院分区：
文献类型：
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作者：
Escobar, Ariel L.;Perez, Claudia G.;Ramos-Franco, Josefina
肌醇 1,4,5-三磷酸 (InsP(3)R) 介导的 Ca2+ 信号传导是调节可兴奋和非兴奋细胞中多种细胞功能的主要途径。尽管 InsP(3) 介导的 Ca2+ 信号传导已被广泛描述，但其对心室心肌活动的影响尚未在整个器官水平的心脏收缩中得到解决。在这项工作中，使用激光扫描共聚焦显微镜和脉冲局部场荧光显微镜研究了完整心脏中 InsP(3) 敏感的细胞内 Ca2+ 信号。通过膜渗透笼状 InsP(3) 的紫外闪光光解，细胞内 [InsP(3)] 迅速增加。我们的结果表明，笼中 InsP(3) 闪光光解后基础 [Ca2+] 增加，而不影响动作电位 (AP) 诱导的 Ca2+ 瞬变。基础 [Ca2+] 升高的幅度取决于紫外线闪光后达到的细胞内 [InsP3]。用兰尼碱预处理未能消除 InsP(3) 诱导的 Ca2+ 释放 (IICR)，表明这种反应不是由兰尼碱受体 (RyR) 介导的。 Thapsigargin 阻止 Ca2+ 从含有 RyR 和 InsP(3)R 的 Ca2+ 库中释放，表明这些库具有相似的 Ca2+ 再摄取机制。这些结果在急性分离的细胞中重现，其中 InsP(3) 的光释放能够诱导内皮细胞的变化，但不能诱导 AP 诱导的心肌细胞瞬变。综上所述，这些结果表明 IICR 并不直接调节心脏兴奋-收缩耦合。据我们所知，这是 IICR 在完整心脏中的首次演示。因此，我们的工作提供了生理条件下 IICR 时空属性的参考框架。 (C) 2012 Elsevier Ltd. 保留所有权利。
Inositol 1,4,5-trisphosphate (InsP(3)R)-mediated Ca2+ signaling is a major pathway regulating multiple cellular functions in excitable and non-excitable cells. Although InsP(3)-mediated Ca2+ signaling has been extensively described, its influence on ventricular myocardium activity has not been addressed in contracting hearts at the whole-organ level. In this work, InsP(3)-sensitive intracellular Ca2+ signals were studied in intact hearts using laser scanning confocal microscopy and pulsed local-field fluorescence microscopy. Intracellular [InsP(3)] was rapidly increased by UV flash photolysis of membrane-permeant caged InsP(3). Our results indicate that the basal [Ca2+] increased after the flash photolysis of caged InsP(3) without affecting the action potential (AP)-induced Ca2+ transients. The amplitude of the basal [Ca2+] elevation depended on the intracellular [InsP3] reached after the UV flash. Pretreatment with ryanodine failed to abolish the InsP(3)-induced Ca2+ release (IICR), indicating that this response was not mediated by ryanodine receptors (RyR). Thapsigargin prevented Ca2+ release from both RyR- and InsP(3)R-containing Ca2+ stores, suggesting that these pools have similar Ca2+ reuptake mechanisms. These results were reproduced in acutely isolated cells where photorelease of InsP(3) was able to induce changes in endothelial cells but not in AP-induced transients from cardiomyocytes. Taken together, these results suggest that IICR does not directly regulate cardiac excitation-contraction coupling. To our knowledge, this is the first demonstration of IICR in intact hearts. Consequently, our work provides a reference framework of the spatiotemporal attributes of the IICR under physiological conditions. (C) 2012 Elsevier Ltd. All rights reserved.