Objeetive To investigate protective effect of trimetazidine on myocardial ischemia/reperfusion injury (MIRI) in rats.Methods Forty Wistar rats were randomly divided into MIRI group (n =10 rats),trimetazidine high-dosage group (n =10 rats; 20 mg/kg),trimetazidine low-dosage group (n=10 rats; 10 mg/kg),and the normal control group (n =10 rats).After MIRI,hemodynamic changes were observed,the concentration of IL-6 and TNF-α was determined,and the cardiac muscle histology under the microscope was observed.Results Hemodynamic studies:Compared to the indices LVSP(198 ±35.5) mmHg,LVEDP (17 ±9.18) mmHg,+ dp/dt max (11050 ± 1517.4) mmHg/s,and-dp/dtmax (9175± 1900) mmHg/s] in the sham-operated group,the indices [LVSP (143 ± 24.5) mmHg,LVEDP (37.5 ±7.16)mmHg,+ dp/dtmax (7450 ± 1755.1) mmHg/s,and-dp/dtmax (6075 ± 1641) Hg/S] in the MIRI group,the indices [LVSP (154.5 ± 31.1) mmHg,LVEDP (31.3 ± 12.6) mmHg,± dp/dtmax (8527.7 ±2251.5) mmHg/s,and-dp/dtmax (6694 ± 2242.2) mmHg/s] in the trimetazidine low-dosage (10 mg/kg)group,the indices[LVSP (168.3 ± 17.6) mmHg,LVEDP (28 ± 10.05) mmHg,+ dp/dtmax (9213.6 ±1747) mmHg/s,and-dp/dtmax (7568 ± 1462.4) mmHg/s] in the trimetazidine high-dosage (20 mg/kg)group,left ventricular remodeling end diastolic pressure (LVEDP),left ventricular systolic pressure (LVSP),and left ventricular pressure maxial rate of rise and fall (± dp/dtmax) were significantly decreased.Compared to the MIRI group,LVSP and ± dp/dtmax in the trimetazidine high-dosage (20 mg/kg)group were significantly increased (P ＜ 0.01),and myocardial damage of MIRI group was more severe in microscope.Compared to the sham-operated group [IL-6 (2556.5 ± 662.9) ng/ml,and TNF-α (134 ± 73.7)ng/ml],the corresponding indices [IL-6 (3664.0 ± 995.7) ng/ml,and TNF-α (443 ± 22.1) ng/ml] in the MIRI group,[IL-6 (3692.8 1545.2) ng/ml,and TNF-α (295 ± 24.2) ng/ml] in the trimetazidiue low-dosage (10 mg/kg) group,and[IL-6(2654.8 ±681.7) ng/ml,and TNF-α(230 ±7.8) ng/ml]in the trimetazidine high-dosage (20 mg/kg) group,the levels of IL-6 and TNF-α were significantly increased.Compared to the MIRI group,the levels of IL-6 and TNF-α were significantly decreased in the trimetazidine high-dosage (20 mg/kg) group (P ＜ 0.01).Conclusions The high-dosage (20 mg/kg) of trimetazidine had a protective effect on myocardial ischemia-reperfusion injury.