Ethanol inhibits Na+-gradient-dependent uptake ofl-amino acids into intestinal brush border membrane vesicles

Abstract

Brush border membrane vesicles from hamster jejunum were used to investigate the effects of ethanol on Na⁺-dependent transport of amino acids. Imposition of an inwardly directed gradient of NaCl resulted in transient accumulation ofl-alanine andl-phenylalanine, followed by a gradual decline to equlibrium levels. Ethanol reduced both the rate of uptake and the maximum accumulation of these amino acids without altering the final equilibrium level. The inhibitory effects of ethanol onl-alanine uptake were dose dependent and reversible. On the other hand, ethanol had no effect on the rate of uptake ofl-alanine or the final equilibrium level attained when vesicles were incubated with a KCl gradient or when NaCl was equilibit Na⁺-dependent uptake of neutral amino acids by direct inhibition of the Na⁺-dependent transport systems for these solutes.