Dietary supplementation with vitamin E ameliorates cardiac failure in type I diabetic cardiomyopathy by suppressing myocardial generation of 8-iso-prostaglandin F2alpha and oxidized glutathione.

Background: Diabetic cardiomyopathy has been documented as an underlying cause of heart failure in diabetic patients. Although oxidative stress has been implicated in diabetic cardiomyopathy, much of the current evidence lacks specificity. Furthermore, studies investigating antioxidant protection with vitamin E in this unique cardiac phenomenon have yet to be performed. In the present study, we sought to determine whether vitamin E supplementation can confer cardioprotective effects against diabetic cardiomyopathy in relation to specific and quantitative markers of myocardial oxidative stress.

Methods And Results: Diabetes was induced in rats by a single injection of streptozotocin. Animals were fed either a basal diet or a diet enriched with 2000 IU of vitamin E per kilogram beginning immediately after induction of diabetes and continued for 8 weeks. Rats were examined for diabetic cardiomyopathy by left ventricular (LV) hemodynamic analysis. Myocardial oxidative stress was assessed by measuring the formation of 8-iso-prostaglandin F2alpha and oxidized glutathione. In the unsupplemented streptozotocin-diabetic rats, LV systolic pressure, rate of pressure increase (+dP/dt), and rate of pressure decay (-dP/dt) were depressed, whereas LV end-diastolic pressure was increased, indicating reduced LV contractility and slowing of LV relaxation. These hemodynamic alterations were accompanied by increased myocardial formation of 8-iso-prostaglandin F2alpha and oxidized glutathione. Vitamin E supplementation improved LV function and significantly attenuated myocardial 8-iso-prostaglandin F2alpha and oxidized glutathione accumulation in streptozotocin-diabetic rats.

Conclusions: These findings demonstrate the usefulness of vitamin E supplementation during the early phases of type I diabetes for the prophylaxis of cardiomyopathy and subsequent heart failure.