Combined effect of fascioliasis and diethylnitrosamine carcinogenesis on the activity of the rat liver monooxygenase system.

1. The activity of the rat liver monooxygenase system after single and combined treatment with Fasciola hepatica and diethylnitrosamine (DENA) has been studied in a 27-week experiment. 2. The changes in lever drug metabolism were due mainly to F. hepatica with DENA having a modulating effect only. 3. The results are discussed with reference to earlier data of ours concerning the effects of stimulation or inhibition of DENA-induced liver carcinogenesis against a background of acute or chronic fascioliasis.