Species Variations in the N - and Ring-Hydroxylation of 2-Acetylaminofluorene and Effects of 3-Methylcholanthrene Pretreatment.

Abstract

Assays for N- and ring-hydroxylation of 2-acetylaminofluorene (AAF) by hepatic microsomes from normal and 3-methylcholanthrene (MC)-treated rats, hamsters, mice, rabbits, and guinea pigs showed marked differences in these enzyme activities in normal animals of the different species and in the effects of MC-treatment. The microsomes of all species, except the guinea pig in which N-hydroxylation could not be detected, showed increases in N-hydroxylation on MC-treatment; the largest increase was observed with hamster liver microsomes. Only rat and mouse liver microsomes showed large increases in ring-hydroxylation activity on MC-treatment. Increases in N-hydroxylation activity of hamster liver microsomes and in ring-hydroxylation activity by rat liver microsomes after MC treatment were inhibited by administration of actinomycin D or puromycin. MC-treatment of rats or hamsters did not affect the reduction of N-hydroxy-AAF by rats and an increased urinary excretion by hamsters.