Cardioprotection with grapes.
Epidemiologic studies suggest that mild-to-moderate wine consumption is associated with a reduced incidence of mortality and morbidity from coronary heart disease. Because wines are produced from grapes, this study was done to determine whether the grapes were equally cardioprotective. Sprague-Dawley male rats were given (orally) standardized grape extract (SGE) (obtained from the California Table Grape Commission, Fresno, CA, U.S.A.) (50, 100, or 200 mg/kg body weight per day) for 3 weeks. Time-matched control experiments were performed by feeding the animals 45 microg/100 g of glucose plus 45 microg/100 g of fructose per day for 3 weeks. After 21 days, rats were killed and the hearts excised and perfused via working mode. Hearts were made ischemic for 30 min followed by 2 h of reperfusion. At 100 mg/kg and at 200 mg/kg, grapes provided significant cardioprotection as evidenced by improved postischemic ventricular recovery (aortic flow, developed pressure, the maximum first derivative of the developed pressure) and reduced amount of myocardial infarction. There were no differences in results between the two groups (100 mg/kg versus 200 mg/kg). No cardioprotection was apparent when rats were given grape samples at a dose of 50 mg/100 g/d. SGE reduced the malonaldehyde content of the heart, indicating reduction of oxidative stress during ischemia and reperfusion. In vitro studies demonstrated that the SGE could directly scavenge superoxide and hydroxyl radicals that are formed in the ischemic reperfused myocardium. The results demonstrate that the hearts of the rats fed SGE are resistant to myocardial ischemia reperfusion injury, suggesting a cardioprotective role of grapes.