Low doses of ethanol decrease the activity of the angiotensin-converting enzyme in the aorta of aging rats and rats treated with a nitric oxide synthase inhibitor and dexamethasone

In the present study, the activity of ACE (angiotensin-converting enzyme) in the aorta of senescent rats and rats treated with the NOS (NO synthase) inhibitor L-NAME (N(G)-nitro-L-arginine methyl ester) or dexamethasone and the effect of low doses of ethanol (0.2-1.2 g/kg of body weight, daily for 8-12 days) on this activity were studied. We found that ACE activity increased with age and in response to L-NAME and dexamethasone treatment. Ethanol at a dose of 0.4 g/kg of body weight per day decreased ACE activity in the aorta of aged rats and of rats treated with L-NAME or dexamethasone to the level of activity in young control rats. The optimal ethanol dose (the dose inducing a maximum decrease in ACE activity) increased with increasing doses of dexamethasone: 0.4 g/kg of body weight per day at 30 mu g of dexamethasone/kg of body weight and 0.8 g/kg of body weight per day at 100 mu g of dexamethasone/kg of body weight. It was also found that optimal doses of ethanol increased the number of cells in the thymus of rats treated with dexamethasone. The optimal dose of ethanol of 0.4 g/kg of body weight per day, which induced a maximum decrease in ACE activity in rat aorta, corresponded to a dose of 30 g of ethanol/day, which, according to epidemiological data, produces a maximum decrease in the incidence of cardiovascular disease in humans. In conclusion, the decrease in ACE activity in vessels may be one of the main mechanisms of the beneficial effects of low doses of ethanol on human health.