[The effect of tetrahydrofuran on the microsomal monooxygenase system in vitro and in vivo].

The effects of tetrahydrofuran (THF) on rat liver microsomes in vitro and in vivo were opposite. In vitro THF inhibited the p-nitrophenol (PNP) hydroxylase activity of microsomes from control rats and from rats treated with PB, acetone, and isoniazide--by 50, 20, 60, and 80%, respectively. THF inhibited dimethylnitrosamine (NDMA) demethylation in control and induced microsomes in a lesser degree. THF increased the total cytochrome P-450 content as well as the contents of cytochromes P-450IIE1 and P-450IIB1/B2. The activities of PNP-hydroxylation and NDMA-demethylation increased also, whereas the PR-dealkylation activity was unchanged. An increase in the THF dose caused inhibition of the rat liver microsomal monooxygenase system.