Disposition of dietary ethanol carbons in rats: Effects of gender and nutritional status

Dietary ethanol is an important contributor to total caloric intake and has been associated with gender-specific alterations in body weight and the risk for coronary heart disease. To understand the metabolic basis of these effects, it is important to first clarify the effects of gender and nutritional state on the metabolic fate of dietary ethanol. Tracer studies were therefore performed using C-14-labeled ethanol in fasted or fed male and female Sprague-Dawley rats (N = 64) previously unexposed to ethanol, 1-C-14-ethanol (4.5 mu Ci) was mixed with unlabeled ethanol (for a total ethanol dose equal to 10% of total daily caloric intake) and a 3-kcal liquid meal and administered through gastric feeding tubes,(CO2)-C-14 production was measured over the subsequent 8 hours. The C-14 content of skeletal muscle, liver, adipose tissue, gastrointestinal (GI) tract, brain, heart, kidney, and serum was determined at 4 time points following tracer administration (20 minutes and 3, 8, and 24 hours; n = 4 at each time point). Tracer content on a whole-body level was significantly greater in skeletal muscle compared with liver in all groups (1.32 +/- 0.02 x 10(6) v 0.27 +/- 0.02 x 10(6) dpm, P < .001). Skeletal muscle tracer content decreased rapidly after 3 hours, whereas liver tracer content remained fairly constant throughout the study period. Fed female rats were the exception, with a significant increase in the tracer content of total liver and liver lipid at 8 hours. The tracer content was higher in the lipid extracts in liver from fed rats compared with fasted rats (1.08 +/- 0.19 x 10(5) v 0.48 +/- 0.08 x 10(5) dpm, P = .002). While male rats exhibited a fairly constant tracer content in adipose tissue throughout the 24-hour period, female rats showed an increase in adipose tissue tracer content at 8 and 24 hours, with levels 3 to 4 times those of the male animals (5.91 +/- 1.42 x 10(4) v 1.55 +/- 0.42 x 10(4) dpm, P = .02). These results demonstrate that (1) skeletal muscle plays an important role in the metabolism of dietary ethanol, (2) the fed state appears to favor the conversion of ethanol-derived carbons to lipid, and (3) female rats have a greater propensity to convert ethanol-derived carbons to lipid and to store these carbons in adipose tissue. Copyright (C) 2000 by W.B, Saunders Company.