Abstract
Male Sprague Dawley rats were injected intraperitoneally with 2-methoxy-4-aminoazobenzene (2-MeO-AAB) or 3-methylcholanthrene (MC), and then the expression of microsomal cytochrome P-450 isozymes in liver and extrahepatic tissues was investigated by means of immunological methods and a bacterial mutation test. The results of protein A-enzyme-linked immunosorbent assaying and immunoblotting using anti-rat cytochrome P-448 monoclonal antibodies showed that MC induced at least two microsomal cytochrome P-448 isozymes, a high spin form (cytochrome P-448 H) and a low spin form (cytochrome P-448 L), in liver, but that it induced only cytochrome P-448 L in extrahepatic tissues such as lung, kidney, small intestine, and colon. The results also indicated that, in contrast to MC, 2-MeO-AAB selectively induced microsomal cytochrome P-448 H in liver but did not induce any cytochrome P-448 isozymes in extrahepatic tissues. The activities of 9, 000 × g supernatants from the individual organs, as to the mutagenic conversion of 3 aromatic amines (3-amino-1-methyl-5H-pyrido (4, 3-b) indole, 2-amino-6-methyldipyrido (1, 2-a:3', 2'-d) -imidazole and 3-methoxy-4-aminoazobenzene), toward Salmonella typhimurium TA 98 bacteria were dependent upon the quantity and/or quality of the microsomal cytochrome P-448 isozymes in the organs.
