Effect of ethanol on choline transport in rat jejunum

Abstract

The effect of ethanol on choline transport across the rat jejunum was studied by intraluminal perfusion in vivo and by influx measurement across the brush-border membrane in vitro. Acute ethanol administration (4 g/kg) through a gastric tube caused an increase in net choline absorption within 1 h. The increase was prevented by pretreatment with pyrazole, an inhibitor of ethanol metabolism. Chronic ethanol administration also caused an increase in choline absorption, the effect being unrelated to the nutritional changes that occur with ethanol ingestion. In contrast, direct instillation of 0.65 M ethanol through the perfusate caused no changes in choline absorption, and the perfusion of a 1.14 M solution even decreased absorption. The in vitro influx of choline across the mucosal membrane of the isolated rat jejunum was also enhanced by pretreatment with ethanol given by gavage 1 h prior to experimentation. Similarly, the ethanol-related increase in the influx rate was inhibited by pyrazole but was unaffected by acetaldehyde or acetate. Like ethanol, pretreatment of rats with methanol stimulated the choline influx rate. The results suggest that ethanol metabolism, rather than the direct effect of ethanol by itself, stimulates the absorption and influx of choline into the rat jejunum. The effect is not produced by the primary metabolites of ethanol, acetaldehyde, or acetate but is very likely related to stimulation by other products of ethanol metabolism.