Acute and chronic exposure to ethanol and the electrophysiology of the brush border membrane of rat small intestine.

In this study we have investigated the effects of (a) chronic ethanol intake on glucose and galactose absorption across the rat jejunum in vivo and on the potential difference across the isolated brush border membrane (Vm) and (b) acute exposure to ethanol (4% or 8%) and acetaldehyde (0.25%) on changes in Vm associated with Na(+)-dependent galactose absorption across the jejunum and ileum. Chronic ethanol intake was associated with hyperpolarization of Vm and an enhanced galactose but not glucose transport. Acute ethanol and acetaldehyde were without effect on Vm whether or not galactose was present. We conclude that while a greater electrochemical gradient across the brush border membrane is a likely explanation for the stimulation of galactose absorption induced by ethanol feeding, factors other than changes in Vm are responsible for the inhibitory effects of acute ethanol.