Abstract: AIM: The study was designed to examine the effect of proteasome inhibitor MG-132 on cardiac structure and function in myocardial infarction rats, and to investigate its mechanism. METHODS: The myocardial infarction model was established by ligating rat's left anterior descending coronary artery. Proteasome inhibitor MG-132 was administered in a dose of 0.75 mg·kg^-1·d^-1 for 7 days. The myocardial pathological change, infraction volume, hemodynamics and brian natriuretic peptide were measured to evaluate the cardiac function; realtime PCR and Western blotting were applied to measure the mRNA and protein expressions of Hsp70 and CHIP. RESULTS: MG-132 decreased the levels of myocardial infraction volume, left ventricular end diastolic presssure and serum BNP (P<0.05). Meanwhile, MG-132 markedly elevated the mRNA and protein levels of Hsp70 and CHIP (P<0.05). CONCLUSION: MG-132 protects myocardium against acute myocardial ischemia injury by inducing CHIP and Hsp70 expression.

Key words: Proteasome inhibitor, Heat shock proteins, Carboxyl terminus of the Hsc70-interacting protein, Myocardial infarction