Objective: To investigate the effects of irbesartan for heart protection and on heart nitric oxide (NO) system in diabetic rats.
Methods: Thirty adult male Wistar rats were randomly divided into three equal groups, namely control group, diabetes group and irbesartan group. Streptozotocin (STZ, 50 mg/kg) was injected to the abdomen to induce diabetes in the rats. After treatment for 12 weeks, the rats were sacrificed and the urine volume, body weight, ratio of heart to body weight, plasma glucose and glycosylated hemoglobin (HbA1c) were measured. NO levels in the serum and myocardium were determined. Inducible nitric oxide synthase (iNOS) expression was determined by immunohistochemistry, and iNOS mRNA detected by RT-PCR.
Results: Urine volume, ratio of heart to body weight, plasma glucose, HbA1C, NO levels in the urine, blood and myocardium in diabetic and irbesartan rats were significantly greater than those of normal controls (P<0.05). The ratio of heart to body weight and NO levels of urine, serum and heart tissue in rats of irbesartan group were significantly decreased as compared with those of diabetes rats (P<0.05). Myocardium iNOS mRNA and protein expression decreased significantly in irbesartan group, but not in diabetes group.
Conclusions: The abnormality in NO and iNOS mRNA expression might be related to diabetic cardiomyopathy. Irbesartan can decrease iNOS mRNA and protein expressions and reduce NO levels in STZ-induced diabetic rats.