代谢性抑制预处理中Na+/Ca2+交换体反向转运的激活触发预处理后的心肌保护作用

目的研究大鼠心室肌细胞在代谢性抑制预处理中钠/钙交换体(NCX)反向转运的活性,以及NCX反向转运抑制剂是否可以阻止代谢性抑制预处理后的心肌保护作用。方法酶解法分离制备钙耐受心肌细胞,用Fura2/AM负载,采用双激发荧光光电倍增系统(IonOptixPhotometrySystem)检测钙信号,用单心肌细胞动缘探测技术观察心肌细胞收缩/舒张功能,台盼蓝染色法检测细胞存活率。结果在代谢性抑制预处理30min时,NCX反向转运被激活。NCX反向转运抑制剂KBR7943(0.5μmol/L)可以抑制代谢性抑制预处理对心肌细胞收缩功能和细胞存活率的作用。NCX激动剂E4031(1μmol/L)可以模拟代谢性抑制预处理后对心肌细胞收缩功能的保护作用,这一作用也可被KBR7943阻断。结论代谢性抑制预处理中,NCX反向转运的激活触发了代谢性抑制预处理后的心肌保护作用;NCX的抑制剂可以阻止代谢性抑制预处理后的心肌保护作用。

Activation of reverse-mode NCX during metabolic inhibition pretreatment triggers the cardioprotection of preconditioning

AIM To study the activity of reverse-mode Na +/Ca2+ exchanger (NCX) during metabolic inhibition pretreatment (MIP) of rat ventricular myocytes, and to determine whether the cardioprotection of metabolic inhibition preconditioning can be prevented by reverse-mode NCX inhibitor. METHODS Single ventricular myocytes were enzymatically isolated and loaded with Fura-2/AM. Intracellular calcium concentration ( Ca2 + ] i ) was measured by IonOptix Photometry System. The activity of reverse-mode NCX was assessed by withdrawal extracellular Na + and the changes of Ca2 + ] iwere measured. The amplitude of single myocyte contraction and cell viability were used as indices of cell injury and death, respectively. RESULTS MIP for 30 min significantly increased the activity of reverse-mode NCX. The effects of MIP on the amplitude of single surviving myocyte contraction and cell viability were attenuated by 0. 5 μmol/L KB-R 7943 (KBR) ,a specific inhibitor of reverse-mode NCX, administered before and during MIP. Pretreatment of cells with 1 μmol/L FA031 , a selective reverse-mode NCX enhancer, mimicked the effects of metabolic inhibition preconditioning on cell contraction, which was also blocked by 0. 5 μmol/L KBR. CONCLUSION During MIP the activation of reverse-mode NCX triggers the cardioprotection of metabolic inhibition preconditioning, which can be prevented by blocking NCX reverse-mode.