Evidence of cardiovascular protection by moderate alcohol: Role of nitric oxide

Epidemiological evidence indicates that moderate alcohol consumption reduces the incidence of heart disease. Endothelial nitric oxide synthase (eNOS) is a key regulator of vascular homeostasis and myocardial functions through the controlled production of nitric oxide ( NO). These studies were conducted to determine if the apparent alcohol-associated cardioprotection is mediated, in part, through modulation of the eNOS protein and activity in the cardiovascular system. Rats were fed alcohol and eNOS protein and NO production were evaluated at the end of 8 weeks. Myocardial and vascular function was assessed ex vivo in a subset of animals. Moderate alcohol improved postischemic myocardial systolic and diastolic function and attenuated the postischemic reduction in coronary vascular resistance. Moderate alcohol also enhanced maximum vascular relaxation by 26 ± 0.2% and increased plasma NO production concomitant with a greater than 2.5-fold increase in eNOS protein. Higher levels of alcohol impaired maximum vascular relaxation by 22 ± 0.1%. These results suggest that moderate alcohol improves postischemic myocardial functions and increases NO production by vascular endothelium. An increase in NO may explain, at least in part, the cardioprotective benefits of moderate alcohol consumption.