Abstract

The absorption of macromolecules from the small intestine of rats was studied in terms of the amount of peroxidase activity that appeared in thoracic duct lymph after a 10 mg dose of horseradish peroxidase had been injected directly into the lumen of the duodenum. When the horseradish peroxidase was injected as a solution in saline no peroxidase activity was detected in the lymph. When ethyl alcohol was included in the dose at final concentrations of 12.5-16% the flow rate of the lymph increased markedly for an hour or so and during this time peroxidase activity was detected in the lymph. An electronmicroscope study of the duodenal epithelium that had been exposed to alcoholic solutions of horseradish peroxidase showed that the enzyme had penetrated between the enterocytes. It was concluded that the presence in the intestine of substantial amounts of alcohol temporarily destabilises the intercellular junctions of the epithelium and thus promotes the absorption of materials which are normally excluded.