Effects of carvedilol on cardiomyocyte apoptosis and gene expressionin vivo after ischemia-reperfusion in rats

Summary The effects of carvedilol on cardiomyocyte apoptosis and expression of bcl-2, bax genes following ischemia (0.5 h) and reperfusion (48 h)in vivo and the possible biological mechanism of carvedilol inhibiting cardiomyocyte apoptosis were studied. The left anterior descending artery in Wistar rats were ligated to establish ischemia-reperfusion (I/R) models. The model animals were divided into two groups: I/R group, the model rats not subject to other treatments except ischemia-reperfusion (n=8): carvedilol-treated group (n=8), I/R model rats treated with carvedilol. Eight rats in the sham-operated group were subjected to only experimental open operation. The number of apoptotic cardiomyocyte was determined by TUNEL staining. Immunohistochemistry andin situ hybridization histochemistry (ISHH) were used to detect the expression of bcl-2 and bax genes. Image processing system was used to quantitatively dispose the positive metric substances of both immunohistochemistry and ISHH through the average optical density (OD) value. The results showed that the number of the apoptotic cells were 36.18±9 (I/R group), 0–1 (sham-operated group) and 9.5±3 (carvedilol-treated group) in each visual field respectively with the difference being very significant among the groups (P<0.001). The OD values of bcl-2 protein in sham-operated group, I/R group and carvedilol-treated group were 0.14±0.01, 0.08±0.02 and 0.15±0.03, respectively. The OD values of bcl-2 mRNA in sham-operated group, I/R group and carvedilol-treated group were 0.08±0.01, 0.06±0.01 and 0.09±0.01, respectively. There was no significant difference between carvedilol-treated group and I/R group (P>0.05). The OD values of bax protein in I/R group, sham-operated and carvedilol-treated-treated group were 0.13±0.02, 0.07±0.01, 0.06±0.01, respectively. There was very significant difference between carvedilol-treated group and I/R group (P<0.01). Bcl-2/bax ratio was 1.07±0.14 (I/R group), 1.28±0.16 (sham-operated group), 2.5±0.26 (carvedilol-treated group) respectively with the difference being very significant between carvedilol-treated group and I/R group (P<0.05). It was indicated that carvedilol could inhibit cardiomyocyte apoptosis following ischemia and reperfusion, which was related to the increased bcl-2/bax ratio due to inhibition of bax gene expression. ZENG Hesong, male, born in 1965, Associated Professor This project was supported by a grant from the National Natural Sciences Foundation of Hubei Province (No. 2000J050).