Objective To investigate the protective effect of pretreatment with Shenfu injectio(SFI)on myocardium against ischemia-reperfusion(I/R)injury in diabetic rabbits.Methods Forty healthy adult male rabbits weighing 2.4-3.2 kg were used in this study.Type I diabetes mellitus was induced by intravenous alloxan 120 mg?kg~(-1) and confirmed by fasting blood glucose＞11.1 mmol?L~(-1).The animals were randomly divided into 5 groups(n=8 each):groupⅠsham operation;groupⅡI/R and groupⅢ,Ⅳ,ⅤSFI+I/R.I/R was produced by occlusion of the anterior descending branch of left coronary artery(LAD)for 60 min.The occlusion of LAD was then released for reperfusion.In sham operation group(Ⅰ)LAD was exposed but not occluded.In groupⅢ,ⅣandⅤSFI 5,10 and 15 ml?kg~(-1) was givenⅣrespectively 30 min before myocardial ischemia.MAP,HR,left ventricular developed pressure(LVDP),?dp/dt_(max),left ventricular end-diastolic pressure(LVEDP)and Vmax were recorded immediately before ischemia(T_0,baseline),at 5 min of ischemia(T_1),immediately before reperfusion(T_2)and at 5,15,60,90,120 min of reperfusion(T_(3-7)).The animals were killed and hearts removed for determination of infarct size and microscopic examination of the ultrastructure of LAD using transmission electron microscope.Results MAP,HR,LVDP,?dp/dt_(max) and Vmax were significantly decreased while LVEDP was significantly increased during reperfusion as compared to the baseline values at T_0 in I/R group. I/R produced myocardial infarct and damage to the endothelial cells of LAD.The harmful effect of I/R was attenuated by different doses of SFI.SFI 10 ml?kg~(-1) provided best effect.Conclusion Pretreatment with SFI can protect the myocardium against I/R injury in diabetic rabbits.SFI 10 ml?kg~(-1) produces better effect.