Objective: To study the effect of Scutellaria baiculensis stem-leaf total flavonoid (SSTF) on myocardial apoptosis and Janus Kinases 2 protein expression during ischemia reperfusion in rats. Method: Forty SD rats were randomly divided into sham operation group

Ischemia reperfusion 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 NS instead of SSTF equally at a week before the operation.Myocardial ischemia reperfusion injury model was established by ligating the left descend coronary artery (LDA) 30 min and reperfusing 2 hours.Apoptosis of myocardial cell was detected after operation in all groups by flow cytometry with AnnexinⅤ-EGFP and propidium iodiode (PI) staining.The protein expression of JAK2 gene was determined by using immunohistochemical staining. Result: Compared with sham group

the occurrence rate of myocardial apoptosis in IR group was increased obviously(P<0.01);JAK2 protein expression was 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 JAK2 protein expression was higher than that in SSTF group(P<0.05

P<0.01). Conclusion: SSTF attenuates cardiomyocytes apoptosis during ischemia reperfusion injury by down-regulating the protein expression of JAK2 gene.