TTX停搏液对心肌α肌动蛋白的影响及机制研究

Effects of cardioplegia with tetrodotoxin(TTX) on myocardialα-actin and its and mechanism

目的:研究Na+通道阻滞剂河豚毒素(Tetrodotoxin,TTX)停搏液对离体大鼠心肌α肌动蛋白(α-actin)的影响及其机制。方法:20只Wistar大鼠随机均分入St.Thomas-2停博组(STH-2组),TTX停博组(TTX组),建立离体心脏Langendorff和Neely灌注模型,搏动稳定后,灌注30min后停搏60min,再灌注60min,观察各组心脏停搏前后的心率(HR)、冠状动脉流量(CAF)、左心室收缩末期压力(LVESP)和压力变化速率(±dp/dt)的恢复率,采用免疫组化检测钙蛋白酶(Calpain),免疫组化和Westernblot检测α-actin的分布及量的变化。结果:恢复灌注后,TTX停搏组的各项心功能恢复率明显优于STH-2组(P<0.01,P<0.05),STH-2组的calpain分布紊乱,表达量明显增多(P<0.01);α-actin分布紊乱,表达量明显减少(P<0.01)。结论:以TTX阻断Na+通道为特点的心脏停搏液对大鼠心肌缺血-再灌注损伤(Myocardial ischemia/reperfusion injury,MIRI)时的α-actin及心功能的保护作用优于STH-2停搏液,其机制可能是直接或者间接的减少激活calpain引起的。

Objective：To investigate the effects of cardioplegia with Na^＋ channel inhibitor tetrodotoxin（TFX）on myocardial α-actin of isolated rat hearts and its and mechanism. Methods： Langendorff and Neely perfusion models were steadily established, then the rat hearts（10 hearts in each group）were arrested by cardioplegia（St. Thomas No. 2 solution,STH-2） in group STH-2,and by cardioplegia （TTX）in group TI＇X respectively after perfusion for 30 minutes. These arrested hearts were remained for 60 minutes and then underwent reperfusion for 60 minutes. Pre-ischemia and post-ischemia hemodynamic parameters of the rat hearts （HR,CAF,LVESP and recovery rate of pressure change speed）were studied and changes of calpain was detected by immunohistochemistry and myocardial α-actin by Western blot and immunohistochemistry. Results：There was no differences between two groups before myocardial ischemia. But the recovery of myocardial hemodynamic parameters during reperfusoin in group TTX was better than that in group STH-2（P〈0.01 or P〈0.05）. Distribution of calpain was disordered and the expression increased（P〈0.01）,and distribution of α-actin was disordered,but the expression decreased significantly（P〈0.01 ）in group STH-2. Conclusion：The protective effects of cardioplegia with Na^＋ channel inhibitor TI＇X on myocardial α-actin and myocardial hemodynamic parameters were better than those in group STH-2 during myocardial ischemia/reperfusion injuries （MIRI）on isolated rat hearts. Mechanism of protection effects was caused probably by activating calpain directly or indirectly.