Absorption and protein binding of N 2 fluorenylacetamide and its metabolites in the bladder of the rabbit

To assess the reactivity of a bladder carcinogen, the absorption by the rabbit (male New Zealand White) bladder mucosa of N 2 acetylaminofluorene (AAF) N hydroxy 2 acetylaminofluorene (N OH AAF), and the N O glucuronide of AAF (N OGl AAF), as well as binding to the protein and RNA of bladder mucosa, was measured in vivo and in vitro. Mucosal pieces incubated for 3 hours in medium containing a carcinogen demonstrated that the fluorene nucleus of both AAF and N OH AAF bound equally with cellular proteins, while N OGl AAF binding was lower. In the presence of an excess of β glucuronidase, however, N OGl AAF showed binding equivalent to its metabolic precursor. After a 3 hour instillation into the bladder lumen of radioactive carcinogens suspended in urine in vivo, transmural absorption of AAF and N OH AAF (90%) was substantial, while N OGl AAF was absorbed less (55%). The renal excretion during this period varied from 18 to 52% of the instilled radioactivity. There was little reactivity of these carcinogens with the mucosal RNA, both in vivo and in vitro. The metabolism of N OH AAF and N OGl AAF was such, both in vitro and in vivo, that the acetyl group was not included in the final protein carcinogen complex in what appeared to be an enzyme reaction.