Effect of late reperfusion of infarct-related coronary artery on cardiocyte apoptosis in a dog acute myocardial infarction model

To investigate the effect of late reperfusion of infarct-related coronary artery on cardiomyocyte apoptosis and expressions of bcl-2/bax in the risk areas in a dog acute myocardial infarction (AMI) model, a total of 28 dogs were randomly divided into the three groups: SHAM group (n=8), AMI group (n=10) and late reperfusion (LR) group (n=10). Coronary artery was exposed after thoracotomy. The left anterior descending arteries were occluded for 12 h in the AMI group, and for 6 h in the LR group followed by reperfusion for 6 h, respectively. The cardiocyte apoptosis was measured by TUNEL assay. The protein and mRNA expressions of bcl-2 and bax were determined by western blot assay, immunohistochemistry and PCR, respectively. The apoptotic index in the LR group was significantly higher than in the sham group (P<0.01), but lower than the AMI group (P<0.05). The mRNA and protein expressions of in the LR group was markedly higher than in the SHAM group (P<0.01), but lower than in the AMI group (P<0.05). Late reperfusion of infarct-related artery can decrease cardiomyocyte apoptosis in the risk area of AMI which may be related to the reduced mRNA and protein expressions of bax.   Key words: Acute myocardial infarction, later reperfusion, cardiomyocyte apoptosis, bax, bcl-2.