Objective: To study the inhibitory effect of total flavonoids from stem/leaf of Scutellaria baiculensis（SSTF） on apoptosis induced by myocardial ischemia /reperfusion in rats.Method: 40 SD rats were randomly divided into sham operation group

ischemia /reperfusion（I /R） group and SSTF group.Rats in SSTF group were perfused with SSTF 17.5

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70 mg·kg-1·d-1 respectively prior to ischemia /reperfusion.Other two groups were given saline instead of SSTF at the same volume from a week before the operation.Myocardial ischemia /reperfusion injury model was established by ligating the left descend coronary artery（LDA） for 30 min and followed by reperfusion for 2 hours.Apoptosis of myocytes was detected after operation in all groups by flow cytometry with Annexin Ⅴ-EGFP and Propidium Iodiode（PI） staining.The mRNA and protein expression of caspase-3 gene were determined by RT-PCR and western blotting.Result: Compared with the sham group

the occurrence rate of myocardial apoptosis in I /R group was increased obviously（P < 0.01）;The expression of mRNA and protein expression of caspase-3 gene were up-regulated in IR group（P < 0.01）.Compared with IR group

the occurrence rate of myocardial apoptosis in SSTF group was decreased obviously（P < 0.05

P < 0.01）;the expression mRNA and protein of caspase-3 gene was higher in SSTF group（P < 0.05

P < 0.01）.Conclusion: SSTF may inhibite myocyte apoptosis during ischemia /reperfusion injury by down-regulating the expression of mRNA and protein of caspase-3 gene.