Cardiac electrophysiology in rats drinking moderate amounts of ethanol

Ethanol (ETOH) exerts a dose-dependent biphasic action on different systems. The deleterious effects of severe drinking are well established. However, little is known about the effects of chronic ingestion of moderate amounts of ETOH. The results presented here are the first obtained in a series of experiments designed to analyze the influence of moderate drinking on cardiac electrophysiology. Rat litter-mates were pair-fed a liquid diet as the only source of food. Rats on ethanol (E) received 14% of total caloric intake of ETOH for an experimental period (EP) of 4, 12, or 24 weeks. The control rats on normal diet (N) received the same diet, except for isocaloric substitution of carbohydrates for ETOH. Diet consumption (DC) and body weight (BW) were measured daily and weekly, respectively. ETOH concentration in blood samples was determined periodically, at random. The animals were decapitated at the end of the EP. The heart was removed, and small right atrial strips were isolated and superfused in a tissue bath with Tyrode's solution at 36 degrees C. Membrane potentials (MP) were measured using intracellular micro-electrodes. DC and BW were the same in E and N during the period prior to ETOH drinking. As soon as ETOH was introduced into the diet, DC became significantly higher in E than in N and remained so throughout the EP. This resulted in an enhanced gain in BW, so that by week 4 and throughout the EP, the BW of E was significantly higher than that of N. Small amounts of ETOH were occasionally found in blood samples from E.(ABSTRACT TRUNCATED AT 250 WORDS)