transfenases in the small intestine as well as the effect of fasting and the possibility of drug induction in this organ. MATERIALS AND METHODS Animals, Treatment, and Preparation of Intestinal Cyto

Glutathione S-transfenase activities have been identified in the small intestine of the rat. Thmreeactivities obtained with p-nitrobenzyl chloride (aralkyl), 1,2-epoxy-3-(p-nitro phenoxy)propane (epoxide), and ethacrynic acid (alkene) as substrates were present in significant amounts. Gel filtra tion indicated an elution volume for the intestinal transfer ase activities that was similar to those activities in the liver and kidney. The induction of the intestinal transferases by polycyclic aromatic hydrocarbons and phenobarbital is sim ilar to those effects observed previously for the hepatic and renal enzymes. The highest concentration of transferase activities occurs in the proximal small intestine; these activ ities are reduced upon fasting. Parallel observations have been reported for aryl hydrocarbon hydroxylases. Because only low or negligible levels of epoxide hydrases have been reported in the small intestine, the glutathione S-transferases may be the primary epoxide-detoxifying system in that on gan.