Cardiomyocyte apoptosis and expression of Bcl-2, Bax protein after acute myocardial infarction and late reperfusion in dogs

AIM: To study the effect of late reperfusion on apoptotic cardiomyocytes in the risk area of acute myocardial infarctin in dogs. METHODS: The experiment was divided into three groups: sham operation group, acute myocardial infarction (AMI) group, and late reperfusion (LR) group. Apart from sham operation group, the other two groups were subjected to left anterior descending branch of coronary artery ligation. The acute myocardial infarction group was only subjected to ligation for 12 hours, late reperfusion group was subjected to ligation for 6 hours following by 6 hours of reperfusion. The cardiomyocyte apoptosis was measured by TUNEL assay. Immunohistochemistry and Western blotting analysis were used to detect the expression of Bcl-2 and Bax protein. RESULTS: The number of apoptotic cardiomyocytes in late reperfusion group was much less than acute myocardial infarction group (P<0.05), and increased significantily as compared with sham operation group (P<0.01). The expression of Bcl-2 protein was enhanced gently in late reperfusion group in contrast to acute myocardial infarction group, but no significant difference in the two groups (P>0.05) was observed, although it was much more in the two groups than that in sham operation group (P<0.01). The expression of Bax protein in late reperfusion group was much higher than that in sham operation group (P<0.01), and was lower than that in acute myocardial infarction group (P<0.05). CONCLUSION: Late reperfusion reduces cardiomyocyte apoptosis in the risk area of acute myocardial infarction. The mechanism may be that late reperfusion can decrease the expression of Bax protein.