Induction of the drug metabolizing system in rainbow trout (Salmo gairdnerii) liver by polychlorinated biphenyls (PCBs).

Clophen A50 is shown to enhance the O–demethylation of p–nitroanisole to p–nitrophenol and to elevate the cytochrome P–450–content of the rainbow trout liver. Three days after feeding, the O–demethylating activity had increased about 4–fold while the cytochrome P–450–concentration was unchanged. This suggests that the process is divided into two or more steps, with an initial lag in the cytochrome P–450 formation. From 7 days and throughout the experiment a concomitant increase in the O–demethylating activity and the cytochrome P–450–content can be observed. The increased activity can not, however, be solely correlated to the increase in cytochrome P–450 content.