Ethanol-provoked disturbances in the binding of zinc to rat jejunal mucosal proteins.

The present investigation was undertaken to determine whether administration of ethanol by intragastric intubation to rats modifies the binding of radioactive zinc to its binding proteins in the jejunal mucosa. These studies were prompted by the frequent observation of abnormalities in serum and urine zinc concentrations in alcoholic patients and the necessity to determine whether alcohol diminishes intestinal protein binding of zinc, the first step in zinc absorption. Adult female rats received intragastric ethanol by intubation, either daily for 10 days, or only 1 hour prior to death. After death by decapitation, the small intestinal was removed, and mucosal cell extracts prepared by homogenization and centrifugation. These extracts were incubated with 65ZnCl2, and gel filtration chromatography was performed with Sephadex G-100. A major difference in the chromatographic profiles between control and alcohol-treated animals was observed: binding of zinc to high molecular weight proteins was reduced and that to low molecular weight proteins was increased. These differences occurred both 10 days and 1 hour after ethanol. The finding of diminished binding of zinc to high molecular weight jejunal proteins may represent the first step leading to diminished intestinal absorption of zinc in alcoholism.