Xenobiotic metabolism in Clara cells and alveolar type II cells isolated from lungs of rats treated with beta-naphthoflavone.

An investigation of several pathways for xenobiotic metabolism in rat lung cells was carried out using enriched fractions of alveolar type II cells (80% purity) and Clara cells (50% purity) which had been prepared from either untreated (control) rats or animals which had been treated with beta-naphthoflavone. Monooxygenase activities (7-ethoxycoumarin deethylase; aryl hydrocarbon [benzo(a)pyrene] hydroxylase) and activities of conjugating enzymes (glutathione transferase; glucuronosyl transferase) were found to be much higher in fractions enriched in Clara cells than in either the crude cell digest or in fractions enriched in type II cells. This was also found to be true for epoxide hydrolase activity. beta-Naphthoflavone treatment of animals was found to increase the monooxygenase and glucuronosyl transferase activities in all cell fractions, but no effect was seen on either glutathione transferase or epoxide hydrolase activity, each of which was extremely low in type II cells.