Characterization of the guinea pig liver microsomal 2-fluorenylamine and N-2-fluorenylacetamide N-hydroxylase.

Many reports in the literature have indicated that the guinea-pig is resistant to the carcinogenic effect of N-2-fluorenylacetamide (2FAA); this refractoriness has been attributed to its lack of N-hydroxylating enzymes. The present communication, however, supports the results of contradictory reports which demonstrate that guinea-pig liver microsomes are in fact able to N-hydroxylate both 2-fluorenamine and 2FAA. The guinea-pig N-hydroxylase activity toward 2-fluorenamine is found to be even greater than the reported activity in the rat and hamster. It is similarly inhibited by 3-methylcholanthrene (3MC), 7,8-benzoflavone (7,8 BF) or miconazole. Activity toward N-2-fluorenacetamide is present in the microsomal preparation from the control guinea-pig. There is slight activation by SKF525A, paraoxon (PX) or sodium fluoride. Under optimum conditions, in the presence of both paraoxon and sodium fluoride, activity is equivalent to that of rat liver microsomal enzymes.