急性心肌梗死延迟再灌注后心肌细胞凋亡与bcl-2和bax基因mRNA表达的研究

Effects of late reperfusion on cardiocyte apoptosis and expression of bcl-2 and bax gene mRNA after acute myocardial infarction in dogs

目的:探讨犬实验性心肌梗死延迟再灌注(LR)后对梗死周边缺血区心肌细胞凋亡及凋亡相关基因bcl-2和baxmRNA表达的影响。方法:健康成年杂交犬28只全麻下常规开胸暴露冠状动脉后随机分为3组:假手术(SHAM)组(8只),急性心肌梗死(AMI)组(10只),LR组(10只)。SHAM组仅行左冠状动脉前降支下穿过丝线而不结扎冠状动脉,AMI组行左冠状动脉前降支高位永久结扎,LR组在高位结扎左冠状动脉前降支6h后松解结扎线予以再灌注6h。共有23只犬模型制作成功。各组犬均于术后12h处死,采集心肌标本。使用脱氧脲核苷酸缺口末端标记法检测心肌细胞凋亡,计算心肌细胞凋亡指数(AI)。逆转录聚合酶链反应法检测心肌细胞中bcl-2和baxmRNA表达水平,以β-actin作为内参照。结果:LR组心肌细胞AI较AMI组明显减少(P<0.05)。与SHAM组相比,bcl-2和baxmRNA在AMI组和LR组的表达均升高(P<0.01),但bcl-2mRNA在该2组间差异无统计学意义(P>0.05);而baxmRNA在AMI组的表达较LR组明显增高(P<0.05)。结论:AMI后LR可以减少梗死周边缺血区心肌细胞凋亡,其机制可能与降低心肌细胞baxmRNA的表达有关。

Objective：To investigate the effects of late reperfusion on cardiocyte apoptosis and expression of bcl-2 and bax gene mRNA in the risk area of acute myocardial infarctin in dogs. Method：Twenty eight dogs were divided randomly into the following three groups： sham operation group （ n = 8）, acute myocardial infarction group （ n = 10）, and late reperfusion group （ n = 10）. Left anterior descending（LAD） branch of coronary arteries were not occluded in the sham operation group. Late reperfusion group was subjected to 6 hours of LAD ligation followed by 6 hours of reperfusion. Acute myocardial infarction group was only subjected to LAD ligation for 12 hours. The number of dogs finished the procedures in each group was 8, 8 and 7, respectively. The cardiocyte apoptosis were measured by TUNEL assay, and the expression of bcl-2 and bax gene mRNA by RT-PCR. Apoptosis index was presented as the number of TUNEL positive cells/the total number of cardiocyte nuclei× 100%. Result： Compared with those of sham operation group,both apoptosis index and expression of bcl-2 and bax gene mRNA were increased significantily in acute myocardial infarction group and late reperfusion group（ P〈0.01 ）. While there was no significant differences of the expression of bcl-2 gene mRNA between acute myocardial infarction group and late reperfusion group（ P〉0.05）. The apoptosis index and expression of bax gene mRNA in acute myocardial infarction group was higher than those in late reperfusion group（ P〈0.05）. Conclusion：Late reperfusion can decrease cardiocyte apoptosis in the risk area of acute myocardial infarction, which may be related to the reduction of bax gene mRNA expression.