Objective:To investigate the influence of proteasome inhibitor MG-132 prior to reperfusion in rat acute myocardial ischemia-reperfusion model whether MG-132 could improve myocardial structure and its function. Methods:44 Adult Sprague-Dawley rats were randomly divided into 3 groups:left anterior descending(LAD)coronary artery ligation for 30 minutes with subsequent 24 hours and 7 days reperfusion (I/R groups)

LAD ligation for 30 minutes with subsequent 24 hours and 7 days reperfusion with treatment by MG-132(I/R+T groups)

and Sham group. After LAD was ligated for 25 min

5 min before reperfusion

MG-132(0.75 mg/kg)was given by vein injection in I/R+T groups

and other groups were given by the same capacity of sterile saline. The incidence of malignant arrhythmia

hemodynamic parameters

the structure of myocardial tissue and the level of B-type natriuretic peptide were measured. Results:Compared with I/R group

the incidence of malignant arrhythmia was decreased (34% vs 67%

P <0.05)

the initiate of ventricular arrhythmia was delayed (102.0±11.0)s vs (406.0±36.7)s

P<0.01

the left ventricular systolic pressure (LVSP)and +dp/dtmax were significantly raised in I/R+T group (126.45±13.41)mmHg vs (108.64±15.61)mmHg

P<0.05;(5 355±754) mmHg/s vs ( 4 860±680 ) mmHg/s

P<0.05

respectively ) . In the same time

we also found that B-type natriuretic peptide were decreased in I/R+T group than in I/R group(231±134)pg/ml vs(1 486±142)pg/ml

P<0.01 and MG-132 can improve the myocardial structure injury and inhibit the ventricular remodeling as well. Conclusion : Our results demonstrate that MG-132 could improve the myocardial structure and function

and play a very important role in myocardial protection.