Coumarin 7-hydroxylase in inbred strains of mice: comparison with other microsomal monooxygenase activities and induction by pyrazole.

This study was carried out in order to find out the effects of pyrazole on liver drug metabolism in several inbred mice: D2, B6, BALB, and AKR and in the outbred mouse NMRI. Compared to control pyrazole treatment decreased the microsomal cytochrome P-450 content of liver to 60-70% and benzo(a)pyrene hydroxylase and ethylmorphine N-demethylase activities to 40-55% and increased 7-ethoxycoumarin O-deethylase activity to 100-200% in AKR, BALB, B6, and NMRI mice and 300% in D2 mouse. Coumarin 7-hydroxylase was increased only 200-300% in B6, AKR, and BALB mice and as much as 700% in D2 and 900% in NMRI mice compared to control. Coumarin 7-hydroxylase is under different genetic control from other monooxygenase activities and differently expressed in various strains of mice.