Objective: To investigate the effect of proteasome inhibitor MG-132 on myocardial infarction size and biochemical marker levels in rat myocardium after reperfusion injury.Methods: Adult Sprague-Dawley rats were randomly divided into 4 groups: left anterior descending(LAD) coronary artery ligation for 30 minutes without treatment(I30min)

LAD ligation for 30 minutes with subsequent 6 hours reperfusion without treatment(I30min/R6h)

LAD ligation for 30 minutes with subsequent 6 hours reperfusion with treatment(I30min/R6h+I30min/R6h) and Sham(Sham30min).After LAD was ligated for 25 min

at 5 min before reperfusion

MG-132(0.75mg/kg)or sterile saline was given to all the treatment group/sham rats

the myocardial infarct size

levels of serum creatine kinases(CK)

CK muscle-brain fraction(CK-MB)

and troponin I(TnI)

were measured.Results: Compared with Sham group

the myocardial infarct size and the ratio of the volume of myocardial infarct over the total volume of left ventricular wall

as well as the levels of serum CK

CK-MB

TnI were significantly increased in I30mingroup(P<0.01).While proteasome inhibitor-MG-132 treatment significantly reduced the size of myocardial infarct and decreased serum CK

CK-MB

TnI levels in I30min/R6h+T group(P<0.05).Conclusion: Our data suggest that myocardial reperfusion injury can be inhibited by proteasome inhibitor MG-132.