Objective To investigate the effects of diabetic mellitus on the opening of mycardial mitochondrial permeability transition pore (MPTP) in rats and explore the role of the opening of MPTP in development of diabetic cardiomyopathy.

Methods 16 male Wistar rats were randomly divided into normal control (NC) group and diabetic mellitus (DM) group. Diabetic mellitus models were established by intraperitoneal injection of streptoaotocin. After 12 weeks, the levels of reactive oxygen species (ROS) and the changes of membrane potential in myocardial mitochondria (MMP) were assayed. Cardiomyocyte apoptosis was evaluted by TUNEL and the level of glutathione (GSH) in serum was measured by spectrophotometer.

Results Compared to the control group, the rate of the ROS generation in the myocardial mitochondria were more significantly increased (5.10%±1.23% vs 2.42%±0.74%, p<0.01) in DM group, but the levels of MMP in the myocardial mitochondria were more significantly decreased (9.65±1.69 vs 19.88±1.38, p<0.01). The apoptotic index was more significantly increased (0.40±0.03 vs 0.26±0.02, p<0.01)and the levels of GSH in serum were more significantly decreased (7.88±1.76 vs 11.97±1.15, p<0.01) in DM group than NC group. It was negative correlation between the rate of the ROS generation and the levels of MMP in the myocardial mitochondria (p<0.05).

Conclusions Diabetic mellitus may lead the mitochondrial oxidative stress and induce MPTP opening and lead to cell apoptottic consequentely.