Musk xylene is a novel specific inducer of cytochrome P-450IA2.

The effect of musk xylene on contents of both cytochrome P-450IA1 and cytochrome P-450IA2 in rat liver was investigated using Western blotting analysis. Rats were treated i.p. for five consecutive days with either 50, 100 or 200 mg musk xylene/kg body weight. Musk xylene increased both total cytochrome P-450 and cytochrome b5 contents in rat liver microsomes. Musk xylene induced cytochrome P-450IA2 (384 pmol/mg protein) strongly and preferentially and the ratio of cytochrome P450IA2/P-450IA1 was about 12 at the lowest dose tested. Musk xylene also induced the cytochrome P-450IA1 dose-dependently, but these extents were very small (32-174 pmol/mg protein). These results suggest that musk xylene may be a more specific inducer for cytochrome P-450IA2 than any other inducers reported.