OBJECTIVETo investigate the effects of angiotensin converting enzyme inhibitor (ACEI) captopril on Calpain-mediated cardiomyocytes apoptosis and cardiac function in diabetic rats.

METHODSThirty adult male SD rats were randomly divided into 3 groups (n = 10), normal control group (NC group), diabetes mellitus group (DM group)and captopril treated group (Cap group). Streptozocin (STZ) were used to make the model of diabetes mellitus, captopril was administrated by gavage at the dose of 50 mg/kg every day, while in NC group and DM group the same volume of normal saline was administrated. Twelve weeks later, left ventricular systolic pressure (LVSP), left ventricular end-diastolic pressure (LVDEP), maximal rise rate of left ventricular pressure (+ dp/dtmax) and maximal fall rate of left ventricular pressure (- dp/dtmax) were detected; Western blot was used to detect the expression of Calpain-1 Calpain-2, Bcl-2, Bax and total Caspase3 protein; apoptosis index (AI) were assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL).

RESULTSCompared with NC group, LVDEP was significantly higher; LVSP, + dp/dtmax and - dp/dtmax were significantly decreased (P < 0.05); Bcl-2 protein expression was decreased; the expression of Calpain-1, Calpain-2, Bax and total Caspase3 protein were increased; the value of AI was significantly increased. Compared with DM group, LVDEP was significantly lower; LVSP, + dp/dtmax and - dp/dtmax were significantly increased (P < 0.05); Bcl-2 protein expression was increased, the expression of Calpain-1, Calpain-2, Bax and total Caspase3 protein were decreased; the value of AI was significantly decreased (P < 0.05).

CONCLUSIONCaptopril can protect diabetic myocardial structure through inhibiting activation of Calpain-1 and Calpain-2, up-regulating the expression of Bcl-2, down-regulating the expression of Bax to inhibit Caspase3 dependent apoptosis, thereby improving the ventricular function and myocardial structure.