Differences in the metabolism of N-2-fluorenylacetamide in the guinea pig and the rat.

are potent carcinogens in several species of animals (33) but have induced no tumors in the guinea pig (1, 8, 22, 30). That this contrasting response might be reflected in the metabolism of these compounds has been the object of several studies. Meade and Ray (21) found more combined diazotizable and less free diazotizable material after an intraperitoneal injection of 2-fluorenamine than was ob tained from similar studies in the rat. The total amount of free plus combined diazotizable materi al was greater in the guinea pig than in the rat, which was interpreted as evidence for less irrevers ible metabolism of 2-fluorenamine to nondiazotizable materials in the guinea pig. Dyer (12) observed larger proportions of nitrite-reacting urinary metabolites after oral administration of Ar-2-fluorenylacetamide to guinea pigs. This was indicative of the formation of more 2-amino-7fluorenol in the guinea pig than in the rat. Urquhart later (30) isolated A"-(7-hydroxy-2-fluore-