Effects of valsartan on diabetic cardiomyopathy in rats with type 2 diabetes mellitus.

BACKGROUND: The development of diabetic cardiomyopathy is multifactorial. Insulin resistance (IR) and excessive activity of the renin-angiotensin system are confirmed reasons for diabetic cardiomyopathy. Renin-angiotensin system (RAS) inhibitors can reduce tissue Ang II levels, with beneficial effects on cardiovascular function. Therefore, in type-2 diabetes mellitus (T2DM), blockade of the RAS may have the function of protecting against diabetic cardiomyopathy through increasing insulin sensitivity and inhibiting excessive activity of RAS. However, this has not been confirmed.

METHODS: The effect of valsartan, an angiotensin receptor blocker (ARB), on diabetic cardiomyopathy in the presence of T2DM was studied. Wistar rats with T2DM and T2DM treated with valsartan were studied. Glucose infusion rates (GIR), index of IR, heart weight, the heart weight-to-body weight ratio (HW/BW), myocardial apoptotic index, cardiac hydroxyprolin content, and cardiac tissue collagen type I and collagen type III content were measured.

RESULTS: GIR in T2DM rats and T2DM rats treated with valsartan decreased (P < 0.01). In T2DM rats treated with valsartan, heart weight, myocardial apoptotic index, cardiac hydroxyprolin content, and cardiac tissue collagen type I and collagen type III content were higher than in control rats, but lower than in T2DM rats. In rats with T2DM, GIR was negatively and significantly correlated with all the variables. However, in T2DM rats treated with valsartan or normal control rats, none of the correlations was significant.

CONCLUSIONS: In the presence of T2DM, diabetic cardiomyopathy is related with IR. Valsartan can not alleviate IR, but can protect against diabetic cardiomyopathy and remove the correlation between IR and diabetic cardiomyopathy.