Characterization of the microsomal cytochrome P-450 species induced in rat liver by trans-stilbene oxide.

trans-Stilbene oxide differs from the classical inducers of drug-metabolizing enzymes, phenobarbital and 3-methylcholanthrene, in that it induces the so-called phase II activities, epoxide hydrolase and glutathione S-transferase, to a much larger extent than it induces cytochrome P-450. Nonetheless, the level of cytochrome P-450 in liver microsomes from rats treated with trans-stilbene oxide is increased significantly to twice the control value. The existence of a number of different isozymes of cytochrome P-450 has now been clearly demonstrated and in the present study we have posed the question. What form(s) of cytochrome P-450 is induced by trans-stilbene oxide? A number of criteria including substrate specificity, pattern of benzo(a)pyrene metabolism, sensitivity to inhibitors, substrate binding spectra, ethylisocyanide binding spectra, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and crossed immunoelectrophoresis were used to answer this question. It seems clear that trans-stilbene oxide induces the same form(s) of cytochrome P-450 as phenobarbital.