The development of mixed function amine oxidase in cultured foetal rat hepatocytes and its relation to 3'-methyl-4-n,n-dimethyl-aminoazobenzene effects on tyrosine aminotransferase accumulation

The ability of cultured foetal rat hepatocytes to metabolize the carcinogen 3'-methyl-4-dimethylaminoazobenzene (MDAB) is shown to correlate with the effectiveness of the carcinogen in suppressing the accumulation of tyrosine aminotransferase (TAT). MDAB is ineffective in cultures of 15-day gestation liver which are unable to carry out oxidation of MDAB as judged by the conversion of [³H]MDAB to a non-ether extractable form. In contrast, 19-day gestation hepatocytes can perform this function, and correspondingly the levels of TAT are suppressed in these cultures in the presence of MDAB. When 15-day gestation hepatocytes are maintained for beyond 3 days in culture, they acquire the ability to oxidize MDAB and accordingly become susceptible to the carcinogen.