Influence of cytochrome P450 mixed-function oxidase induction on the acute toxicity to rainbow trout (Salmo gairdneri) of primary aromatic amines.

The influence of enzyme induction on the acute toxicity of aniline and 4-chloroaniline to rainbow trout (Salmo gairdneri) was investigated. For these two xenobiotics, bioactivation reactions are known to occur in mammals. Induction of cytochrome P450 mixed-function oxidase was obtained by intraperitoneal (ip) injection of trout with a mixture of polychlorinated biphenyls (Aroclor 1254). Five days after ip injection with three different doses of Aroclor 1254 (50, 100, and 200 mg/kg), benzo[a]pyrene hydroxylase activity in trout liver microsomes increased five- to sixfold. Cytochrome P450 concentrations in the microsomes were slightly, but significantly, enhanced in two of the three dose levels. The 96-hr LC50's of aniline and 4-chloroaniline were not affected by pretreatment with Aroclor 1254, suggesting that metabolic activation does not necessarily play a role in the acute toxicity of aromatic amines to fish.