血管紧张素Ⅱ对大鼠心肌细胞Ca^(2+)信号的影响

EFFECTS OF ANGIOTENSIN Ⅱ ON Ca^(2+) SIGNAL IN CULTURED RAT CARDIAC MYOCYTES REVEALED BY CONFOCAL LASER SCANNING MICROSCOPY

目的:在培养的新生大鼠心肌细胞上,观察AngⅡ对Ca2+信号的影响,探讨其时间和空间形式。方法:以Fluo4/AM荧光指示剂负载培养的心肌细胞,应用激光共聚焦扫描显微镜观察其变化。结果:在激光共聚焦显微镜下,观察到不论静息或受AngⅡ刺激的心肌细胞,均可见钙波在细胞内及相连的另一细胞间彼此传播的现象。正常心肌细胞内核的荧光强度高于核周与细胞浆,且存在小幅度的钙震荡,AngⅡ(10-6mol/L)引起心肌细胞的核Ca2+和胞浆Ca2+荧光强度升高的同时,其钙震荡幅度明显升高,外源性一氧化氮(NO)供体硝普钠(10-5mol/L)使钙的周期性震荡消失,荧光强度降低。同时还观察到加入AngⅡ(10-6mol/L)后在部分心肌细胞膜上的不同部位,出现不能传播的钙闪烁团,在此基础上再加入硝普钠(10-5mol/L),不能取消AngⅡ所致的钙闪烁现象。结论:心肌细胞受AngⅡ刺激,可产生多种钙信号形式如钙闪烁、钙波、钙震荡以及瞬时性钙增高,可能在介导细胞功能的调节中起重要作用。

Aim: The effects of angiotensin Ⅱon the changes of Ca^(2+) signal in cultured rat neonatal myocytes were investigated in order to reveal the localization and distribution of elementary Ca^(2+) signaling units. Methods: The cultured neonate rat myocytes were treated with angiotensin Ⅱ, and calcium signal was detected using confocal laser scanning microscopy and fluo-4/AM calcium probe. Results: The propagation of Ca^(2+) waves was observed in rest and angiotensin Ⅱstimulated cardiac myocytes. Calcium fluorescent intensity oscillated slightly in myocytes and the average intensity was much higher in the nucleus than in the cytosole, all of which could be magnified significantly by AngⅡ(10^(-6) mol/L). Ca^(2+) oscillation induced by AngⅡ was completely blocked by NO donor sodium nitroprusside. AngⅡ evoked Ca^(2+) sparks close to the cell surface membrane, and couldn't be abolished by sodium nitroprusside. Conclusion: There are spatiotemporal dynamics of Ca^(2+) signaling patterns such as Ca^(2+) wave, Ca^(2+) spikes, Ca^(2+) oscillation and the whole cell Ca^(2+) transients induced by angiotensin Ⅱ, which might play very important roles in cellular cardiac function.