[Effect of the combined and separate administration of phenobarbital and 3-methylcholanthrene on liver benzopyrene hydroxylases in "sensitive" and "resistant" inbred mice].

Combined induction of liver monooxygenases with 3-methylcholanthrene (3-MC) and phenobarbital (PB) has been studied in experiments on DBA/2 and C57B/6 mice. As is known, PB increases the number of intracellular receptor sites for polycyclic hydrocarbons. When DBA/2 mice resistant to the induction were pretreated with PB, there were no signs of induction common to those induced by 3-MC. In similar experiments with the sensitive C57BL/6 mice, PB and 3-MC produced additive effects on the induction of liver monooxygenases.