Induction of Monooxygenases in Rhesus Monkeys by 3-Methylcholanthrene: Metabolism and Mutagenic Activation of N-2-Acetylaminofluorene and Benzo[a]pyrene

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Abstract
Induction of content and activity of hepatic and lung cytochrome P450-dependent monooxygenases by 3-methylcholanthrene (MCA) was studied in male rhesus monkeys. Hepatic microsomes were concomitantly studied for mutagenic activation of N-2-acetylamlnofluorene (AAF) as well as with the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Hepatic N-hydroxylation of AAF was increased sixfold to sevenfold after MCA treatment; aryl hydrocarbon hydroxylase was similarly increased in both liver and lung. The hepatic cytochrome P450 content was increased by 50%, and the Soret maximum in the CO-hemoprotein complex was shifted to the blue by 2 nm after MCA induction. Electrophoresis of hepatic microsomes from MCA-treated monkeys showed an increase in a polypeptide band of 54,000 molecular weight. Mutagenic activation of AAF by liver microsomes from untreated rhesus monkeys was low but was increased 40-fold after MCA treatment. No effect was observed on the mutagenic activation of N-hydroxy-2- acetylaminofluorene by liver microsomes after MCA treatment. Rhesus monkeys may provide a model for evaluation of the role of polycyclic hydrocarbon induction in chemically caused cancer and toxicity in primates.