3-nitrotyrosine, a biomarker for cardiomyocyte apoptosis induced by diabetic cardiomyopathy in a rat model.

The aim of this study was to investigate whether 3-nitrotyrosine (3-NT) may serve as a predictive biomarker for cardiomyocyte apoptosis in a diabetic cardiomyopathic rat model. Using male Sprague-Dawley (SD) rats in a prospective, randomized, controlled study, a diabetic type II animal model was established by injection with streptozotocin. The diabetic group and the diabetic cardiomyopathy (DCM) group were administered valsartan. This study revealed the following: i) The ratio of heart/body weight increased in the DCM, diabetes administered with valsartan (D+V) and DCM+V groups compared with the N group. ii) The expression index (EI) of 3-NT correlated positively with the apoptotic index (AI) of the cardiomyocytes, whereas 3-NT in the serum did not reflect changes in the AI. iii) The AI of the DCM group was the highest of the assessed groups. The AI of the DCM group was higher than that in the D+V group, and the AI of the DCM+V group was higher than that of the N group. iv) The EI of 3-NT increased with a higher AI. The higher the EI of 3-NT, the higher the AI observed in rat cardiomyocytes. Both the EI of 3-NT and the AI of the DCM group were higher than in the other groups. However, both the EI of 3-NT and the AI in the DCM group markedly decreased for the DCM+V group. 3-NT in the myocardial tissue of rats was deemed to be a successful biomarker for predicting cardiomyocyte apoptosis in SD rats. 3-NT levels were significantly increased and related to cardiomyocyte apoptosis. Valsartan post-treatment reversed the increase of 3-NT and apoptosis in diabetic cardiomyopathy.