TY - JOUR T1 - Immunological Comparison of Hepatic and Extrahepatic Cytochromes P-450 JF - Molecular Pharmacology JO - Mol Pharmacol SP - 154 LP - 164 VL - 15 IS - 1 AU - F. PETER GUENGERICH AU - PATRICIA S. MASON Y1 - 1979/01/01 UR - http://molpharm.aspetjournals.org/content/15/1/154.abstract N2 - Antibodies were raised to two apparently homogeneous cytochromes P-450 prepared from liver microsomes of phenobarbital- and 3-methylcholanthrene-treated rats; microsomal fractions were prepared from the livers, lungs, kidneys, testes, spleens, hearts, small intestines, colons, stomachs, and brains of untreated and phenobarbital- and 3-methylcholanthrene-treated rats. Cross reactivity was observed in each tissue with at least one of the two antibodies as judged by immunodiffusion analysis. Inhibition of benzo(a)pyrene hydroxylase or 7-ethoxycoumarin O-deethylase activity was observed with microsomes prepared from each tissue with the exception of spleen and colon; inhibition curves were dependent upon the substrate and antibody used as well as the pretreatment of the animals from which the microsomes were prepared. As a general rule, microsomes prepared from 3-methylcholanthrene-treated rats were inhibited most readily by antibody raised to cytochrome P-450 isolated from liver microsomes prepared from 3-methylcholanthrene-treated rats, and the same general rule held for phenobarbital induction; however, several exceptions were noted. On the basis of these results, the microsomal P-450s of extrahepatic tissues are, in general, immunologically similar to the major hepatic microsomal P-450s in the rat. ACKNOWLEDGMENTS We are thankful to Drs. R. A. Neal, F. Chytil, and D. E. Ong for the use of their fluorimeters. ER -