ETHANOL EXERTS ACUTE PROTEIN-SPARING EFFECTS DURING POSTABSORPTIVE BUT NOT DURING ANABOLIC CONDITIONS IN MAN

Ethanol abuse is frequently associated with protein malnutrition. To a ssess the acute effects of ethanol on whole-body protein metabolism, [ 1-C-13]leucine kinetics were measured in eight postabsorptive normal m ale subjects three times, ie, during administration of two doses of et hanol (dose 1, 0.52 g/kg during 2 hours and 0.3 g/kg during 3 hours; d ose 2, 0,69 g/kg during 2 hours and 0.3 g/kg during 3 hours) and durin g saline (controls), During the last 2 hours of the studies, glucose, insulin, and amino acids were infused to assess the effects of ethanol on protein kinetics under anabolic conditions (euglycemic clamp), The decreases in leucine flux (reflecting whole-body protein breakdown) a nd nonoxidative leucine disappearance (a parameter of protein synthesi s) during saline infusion were abolished in both ethanol protocols (P <.05 or less v saline), The rate of leucine oxidation decreased during the higher dose of ethanol compared with saline (P <.005), indicating an anticatabolic effect. During anabolic conditions (clamp), leucine flux and nonoxidative leucine disappearance were significantly higher in both ethanol studies compared with saline(P <.05), Resting energy e xpenditure (REE) and oxygen consumption (Vet) during the euglycemic cl amp increased to a greater degree during both ethanol studies than dur ing saline (P <.05 or less), Thus, an elevation of blood ethanol conce ntrations to the levels observed in social drinking results in a net a nticatabolic effect (diminished leucine oxidation) when ethanol is adm inistered alone, However, during administration of other nutritional s ubstrates, the anticatabolic effect was not detectable, possibly becau se ethanol enhanced nutrient induced thermogenesis, Copyright (C) 1997 by W,B. Saunders Company.