Chronic ethanol consumption, stress, and hypertension.

A reliable method of producing physical stress in the rat was developed using heat irradiation, and the possible interaction between chronic ethanol consumption and stress was investigated in a rat model of alcoholism. Chronic heat stress and chronic ethanol consumption each produced mild hypertension in rats. When combined, the two treatments resulted in hypertension more severe than that produced by either stress or ethanol consumption alone. The group of animals receiving both treatments also exhibited high mortality. Investigations into the mechanisms responsible for the apparent additive effects of the two treatments revealed that the animals in this group had the highest circulating norepinephrine levels. The plasma volumes, however, were not different between the stressed groups and their unstressed counterparts. As the plasma norepinephrine level usually reflects overall sympathetic tone of an animal, our results suggest that the additional hypertensive effect of chronic stress on the ethanol-treated animals is associated with increased sympathetic nervous activity and is not a result of expanded plasma volume. These findings may have clinical implications for human alcoholics and in the analysis of cardiovascular risk factors in hypertensive patients.