Objective: To study the protective effect of Xinnaosu extract on myocardi ischemic injury induced by isoproterenol(ISO) in rats and discuss its mechanism of action. Method: SD rats were randomly divided into six groups

normal group

model group

positive control 0.135 g·kg-1 group(Heart-protecting musk pill 0.135 g·kg-1)

Xinaosu extract low

medium and high dose groups(0.055

0.276

1.38 g·kg-1)

n ≥ 10 in each group. Rats were injected with isoproterenol to induce myocardial infarction models. From the second day after modeling

rats were givenwith Xinaosu extract ig(0.055

0.276

1.38 g·kg-1)for consecutive 14 d.Abdominal aortic blood samples were collected to detect the level of creatine kinase(CK)

lactic clehydrogense(LDH)

superoxide dismutase(SOD) and malondialdehyde(MDA). Hearts were collected for hematoxylin and eosin(HE) staining and histomorphology changes were observed by light microscope.Immunohistochemical technique was done with CD34 monoclonal antibody to mark cardiac microvascular endothelial cells

and calculate microvascular density(MVD). Result: Compared with the normal group

the activity of CK

LDH and level of MDA in model group showed a significant increase(P<0.01). Compared with model group

the middle and high dose of Xinnaosu extracts both showed significant decrease in the activity of CK and LDH as well as the level of MDA(P<0.01)

and significant increase in SOD activity(P<0.01)

endothelial angiogenesis and MVD(P<0.01). Conclusion: Xinnaosu extract has protective effect on myocardial ischemic injury induced by isoproterenol in rats. Its mechanism may be related to upregulating the expression of angiogenesis and reducing oxidative damages.