缺氧易化快速起搏引起的心室肌细胞钙瞬变交替

Hypoxia facilitates rapid pacing-induced calcium transient alternations in ventricular myocytes

目的:探讨缺氧对快速起搏诱导的心室肌细胞钙瞬变交替的影响。方法:分离成年SD大鼠心室肌细胞,并将其置于无血清的低氧液中以建立缺氧性心肌损伤的体外模型;采用激光扫描共聚焦显微镜观察心室肌细胞的钙瞬变及钙瞬变交替情况;应用WST-8试剂盒检测心室肌细胞线粒体的功能状况。结果:在正常情况下,成年SD大鼠心室肌细胞呈棒状,低频起搏(60～240 min-1)可引起钙瞬变现象,但不引起钙瞬变交替。当起搏频率增加至(288±27)min-1时,可诱导钙瞬变交替现象。缺氧处理后,心室肌细胞的形态学无明显改变,但钙瞬变交替的阈值频率降低为(227±26)min-1,与对照组比较差异具有统计学意义(P<0.05)。另外,缺氧处理还可使线粒体脱氢酶的相对活性从(100.2±8.7)%降低至(57.6±7.5)%,而L-型钙通道阻滞剂可部分抑制缺氧诱导的线粒体脱氢酶活性降低。结论:缺氧处理可易化快速起搏诱导的心室肌细胞钙瞬变交替,而钙瞬变交替可能介导了缺氧引起的线粒体功能受损。

To explore the effect of hypoxia on rapid pacing - induced calcium transient alternations in ventricular myocytes. METHODS ： Ventricular myocytes were isolated from the heart of adult SD rats and cultured in serum - free hypoxic fluid to set up an in vitro model of hypoxia - induced cardiac injury. The calcium transient and its alterna- tions were investigated under confocal laser scanning microscope. The mitochondrial function was also examined by WST - 8 kit. RESULTS： Under normoxic condition, the ventricular myocytes were claviform. Low frequency of pacing, ranging from 60 to 240 min-1, induced calcium transient, but not calcium transient alternations, which was elicited by the pacing over a threshold frequency of （288 ＋ 27） rain- 1. Exposure of the ventricular myocytes to hypoxia did not obviously affect the morphology of the cells, but reduced the threshold frequency of pacing to （227 ~ 26） min- 1 （p 〈 0.05 ）. Additionally, exposure of the cells to hypoxia repressed the activity of mitochondrial dehydrogenase from （ 100.2 ~ 8.7 ） % （ control group） to （57.6 ~ 7.5 ） %, which was partially blocked by L - type Ca2 ~ channel inhibitor. CONCLUSION： Hypoxia fa- cilitates calcium transient alternations induced by rapid pacing, and the calcium transient alternations are involved in the hypoxia- injured mitochondria function.