作者：沈建新，陈耀文，王海燕，韩太真 【关键词】 钙释放 Regulation of sarcoplasmic reticulum Ca2+ content depletion on cardiac Ca2+ release 【Abstract】 AIM: To systematically investigate the effects of sarcoplasmic reticulum (SR) Ca2+ content depletion on cardiac Ca2+ release. METHODS: Thapsigargin, a potent SR Ca2+ pump inhibitor, was used to deplete the SR Ca2+ content. The SR Ca2+ content was estimated by traditional caffeine puff. The global Ca2+ release was evoked by local field stimulation and the intracellular Ca2+ signal was recorded by the laser scanning confocal microscope. RESULTS: The results showed that thapsigargin decreased the SR Ca2+ content in a dosedependent and nonlinear timedependent manner. The intracellular Ca2+ release decreased with the depletion of SR Ca2+. But these two decreases were not parallel to each other. A slight depletion of SR Ca2+ could lead to a significant decrease of Ca2+ release. When SR Ca2+ depleted to a certain degree (though still much higher Ca2+ in SR than in plasma), only little or no Ca2+ release could be triggered by field stimulation. CONCLUSION: The results suggest that SR Ca2+ content has some important nonlinear regulatory effect on intracellular Ca2+ release. 【Keywords】 Ca2+ release; microscopy, confocal; sarcoplasmic reticulum; myocardium/cytology 【摘要】 目的： 较系统地研究肌浆网(SR)内钙容量的减少对心肌细胞钙释放的影响. 方法： 采用肌浆网膜的钙泵抑制剂thapsigargin（TG）耗减SR内钙容量，以喷咖啡因的方法估测SR内钙容量，以局部场刺激的方法诱发全细胞的钙释放. 胞内钙信号的变化均采用激光共聚焦显微镜的方法记录. 结果： SR钙泵抑制剂TG以剂量依赖和非线性的时间依赖方式引致心肌细胞SR内钙容量的耗减，而钙容量的耗减可相应地引起全细胞水平的钙释放减少. 但二者的变化不完全平行，SR内钙容量的少量减少即可引起胞内钙释放的显著减少，而当SR内钙耗减到一定程度后（虽然此时SR内Ca2+仍远高于胞质内钙），场刺激已很难或无法引致钙释放. 结论： 心肌细胞SR内钙容量对胞内钙释放具有重要的非线性调节作用.
