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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 effect of delayed and reperfusion (LR) on myocardial apoptosis and the expression of apoptosis-related genes bcl-2 and baxmRNA in ischemic myocardium in dogs with experimental myocardial infarction. Methods: Thirty - eight healthy adult dogs were randomly divided into 3 groups: sham - operation (8), AMI (10), LR 10). In the SHAM group, only the left anterior descending coronary artery passed through the thread without ligating the coronary artery. The left anterior descending coronary artery of the AMI group was permanently ligated and the ligation of the anterior descending branch of the left coronary artery was lightened in the LR group Reperfusion 6h. A total of 23 dogs model made. The dogs in each group were sacrificed at 12h after operation, and the myocardial samples were collected. The apoptosis of cardiomyocytes was detected by the terminal deoxynucleotidyl transferase nick end labeling method, and the cardiomyocyte apoptosis index (AI) was calculated. Reverse transcription-polymerase chain reaction was used to detect the expression of bcl-2 and bax mRNA in cardiomyocytes. Β-actin was used as internal reference. Results: Compared with AMI group, the AI of myocardial cells in LR group decreased significantly (P <0.05). Compared with SHAM group, the expression of bcl-2 and bax mRNA in AMI group and LR group increased (P <0.01), but there was no significant difference between the two groups (P> 0.05); while bax mRNA The expression in AMI group was significantly higher than LR group (P <0.05). CONCLUSION: LR after AMI can reduce the apoptosis of ischemic myocardium in infarcted area, which may be related to the decrease of bax mRNA expression in cardiomyocytes.