一氧化氮介导的二氮嗪预处理的心肌保护机制

摘要

OBJECTIVE To explore the mechanism of protective effects on myocardium ischemia - reperfusion ( I/R ) injury by diazoxide preconditioning ( DPC ). METHODS Isolated beating heart models of 40 Wistar rats were set up and were divided randomly into four groups. The I/R group ( n = 10 ): Equilibrium perfusion of 30 minutes was followed by a 60 minutes reperfusion. The DPC group ( n = 10 ) had a 10 - min equilibration and two cycles of 5 min of 100 μM diazoxide perfusion followed by a 5 - min diazoxide - free period before the 30 min ischemia and a 60 - min reperfusion. The blank control ( n = 10 ) and the DMSO group ( n = 10 )were peffused with the same treatment as in the DPC group, excepting that diazoxide was replaced with natriichloridum and DMSO. The activity of creatine kinase ( CK ) in coronary outflow, the activity of malonyldialdehyde ( MDA ) and superoxide dismutase ( SOD ) in myocardium were detected. The concentrations of myocardial nitric oxide ( NO ) and cyclic guanosine monophosphate ( cGMP ) were also assessed. RESULTS In DPC group, the content of CK and MDA were significantly less than those in other groups ( P ＜ 0.01 ),and the activity of SOD was much higher than other groups ( P ＜ 0.01 ). However, there were no significant changes among I/R group, DMSO group and blank group ( P ＞ 0.05 ). The NO and cGMP concentrations in DPC group were much higher than other groups ( P ＜0.01 ), but there were no significant changes among I/R group, DMSO group and blank group ( P ＞ 0.05 ). CONCLUSION The NO - cGMP signaling pathway mediated by NO may be involved in triggering the process of myocardial protection mechanisms of DPC.%目的 探讨二氮嗪预处理(DPC)对心肌缺血再灌注损伤保护作用的机制.方法 Wistar大鼠40只,建立离体心脏Langendorff灌注模型,随机分成四组:缺血再灌注组(I/R组,n=10):在心脏平衡灌流30 min后,缺血30 min再灌注K-H液1 h;二氮嗪预处理组(DPC组,n=10):在心脏平衡灌流10 min后,给予含二氮嗪(100 μmol/L)的K-H液灌注5 min,再复灌不含二氮嗪的K-H液5 min后,再给予含二氮嗪的K-H液灌注5 min,再复灌不含二氮嗪的K-H液5 min,然后缺血30 min,再灌注K-H液1 h;空白对照组(n=10):用等量盐水代替二氮嗪,过程同DPC组;二甲基亚砜组(DMSO组,n=10):用DMSO代替二氮嗪,过程同DPC组.检测各组缺血前及复灌30 min后冠脉流出液中肌酸激酶 (CK) 的活性、心肌组织丙二醛(MDA)及超氧化物岐化酶(SOD)活性、心肌组织一氧化氮(NO)及环磷酸鸟苷(cGMP)表达.结果 DPC组与其他组比较,冠脉流出液CK活性较明显减少(P<0.01),MDA含量明显减少(P<0.01),SOD含量明显增加(P<0.01),I/R组与DMSO及空白对照组比较差异无统计学意义(P>0.05).心肌组织NO、cGMP含量:DPC组较其他组明显增加(P<0.01),I/R组与DMSO及空白对照组比较差异无统计学意义(P>0.05).结论 NO介导的NO-cGMP信号通路可能参与DPC心肌保护机制的触发过程.