Effect of Oral Nitrate Administration on Myocardial Injury in Type 2 Diabetic Rats

Cardiovascular diseases are the most important complications of diabetes, representing the ultimate cause of death in more than half of all patients with the disease. Nitrate has been demonstrated to be an effective add-on therapy in patients with heart failure but no study has been yet addressed the effect of nitrate therapy on myocardial injury associated with diabetes. The aim of this study was therefore to assess the effect of nitrate therapy on myocardial injury in type 2 diabetic rats. Thirty-two adult male Wistar rats were divided into four groups (n=8): Control, control+nitrate, diabetes, and diabetes+nitrate. Type 2 diabetes was induced by injection of nicotinamide (95 mg/kg) 15 min before injection of streptozotocin (65 mg/kg). Nitrate in control+nitrate and diabetes+nitrate groups was added to the drinking water (100 mg/L for 2 months). Serum nitrate+nitrite (NOx), CK-MB, and LDH were measured before and at the end of the study and heart malonyldialdehyde (MDA) was measured at the end of the study. Nitrate therapy in diabetic rats significantly increased serum NOx levels (29.2±5.6 vs. 42.8±9.8 μmol/L, P<0.05), decreased heart MDA levels (9.7±1.2 vs. 6.2±0.6 μmol/L, P<0.05), and decreased serum levels of both CK-MB (471.0±29.7 vs. 284.9±10.3 U/L, P<0.05) and LDH (791.6±21.9 vs. 497.8±13.1 U/L, P<0.05). Nitrate therapy provided cardioprotection by increasing NO levels and decreasing oxidative stress in type 2 diabetic rats.