OBJECTIVE:To evaluated the effect of calycosin on left ventricular ejection fraction and angiogenesis.METHODS:Adult male Sprague-Dawley rats were randomly assigned into calycosin-treated groups(0.5,1,2,and 4 mg/kg qd),a dimethyl sulfoxide(DMSO),or a sham-operated control group.The myocardial ischaemia(Ml) model was intraperitoneally administered calycosin for 28 days.The survival rates and left ventricular ejection fractions(LVEF)were compared between groups.The expression levels of vascular endothelial growth factor(VEGF)and cluster of differentiation 31(CD31) in ischaemic myocardium were also measured and compared.RESULTS:The construction of MI model resulted in a LVEF reduction of 50% compared with the sham-control.After 28 days,the LVEF value was 10% higher when calycosin(4 mg/kg) was administered compared with the DMSO group.The expression of VEGF and CD31 showed a dose-dependent manner when calycosin was administrated.The calycosin-treated(4 mg/kg) group displayed a twofold increase in VEGF expression at both the mRNA and protein levels compared with the DMSO group.In addition,CD31 expression in the microvascular increased 1.5-fold in the 4 mg/kg calycosin-treated group.CONCLUSION:Calycosin improved left ventricular ejection fraction in the MI rat models,induced VEGF expression in the ischaemic myocardium,increased CD31 expression and promoted angiogenesis.