Abstract: Objective: To explore the effect of the Shu-mai capsule (SMC) on apoptosis in rats with myocardial ischemia (MI). Methods: Rats with a ligated left anterior descending coronary artery (MI model) were randomly divided into the high and low dose of the SMC groups (SMCH and SMCL), the Dan-shen drop pill group（DSP）and the MIR group. A sham-operation group (Sham) was also enrolled in this study. Four weeks later, the ratio of apoptotic to normal cells, the expression of bax and bcl-2 protein, and the ultramicrostructure of the myocardium were respectively determined by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling (TUNEL) assays, immunohistochemical staining, and transmission electron microscopy（TEM）. Results: The SMC can reduce the expression of bax, increase the expression of bcl-2 and reduce the apoptosis. Under TEM, in the MIR group some left ventricular tissues were obtained， the nuclear membrane shrank and nuclear chromatin condensed and congregated under the nuclear membrane like speckle，abutting against the nuclear envelope, and pyknosis was found by chance. The mitochondria of some myocardial cells were markedly swollen with some disorganized or disrupted mitochondrial cristae which displayed as an uneven vacuole． Compared with the MIR group, the ultramicrostructure of the SMCH and the DSP groups was improved.Conclusion: High dose SMC can effectively suppress the apoptosis and protects rats against myocardial ischemia.

Key words: Shu-mai capsule, Myocardial ischemia, Apoptosis, Bax, bcl-2