Metabolism of the glucuronide of N-hydroxy-2-acetylaminofluorene in the rat.

If N-G1O-AAF were involved in the mechanism of action of AAF in species susceptible to carcinogenesis by AAF, then one would also expect N-GbO-AAF to be carcinogenic. In a prelimi nary test, carried out at bow dose because of the limited availa biity of N.GbO-AAF, tumor development did not occur within 12 months after repeated subcutaneous injections of either the sodium or cupric salts, or of the tniacetyl methyl ester of N-G1O-AAF, into female rats while N-HO-AAF did induce high incidences of tumors in female rats3 (11). N-G1O-AAF is a highly polar conjugate and is extremely sob uble in aqueous systems (4). Since the preliminary carcino genicity assays were carried out using tricaprylin as a solvent (11),we wantedto repeat thesetestsusingaqueous solvents, as well as giving the glucuronide at higher doses over a longer period of time. Because the gbucuronide must be prepared bio synthetically (4), and therefore is not available in unlimited quantities for testing, we wanted to obtain some information on the metabolism of this compound in the rat after admini stration by various routes before starting the carcinogenicity assays. Results of these studies are described herein. General Albino rats, weighing about 200 gm, were obtained from the Holtzman Company, Madison, Wisconsin, and were maintained on Purina laboratory chow and water ad libitum. Bile duct 3ln these experiments, we were primarily interested in the relative degree of carcinogenicity of N-GlO-AAF as compared to N-HO-AAF when tested under identical conditions. Thus, while the glucuronide derivatives of N-HO-AAF were much less active than N-HO-AAF under the conditions tested (11), some tumors with long latent periods arose in the rats which were injected with the glucuronide derivatives of N-HO-AAF. The cumulative tumor incidences at 20 months for rats injected with the sodium salt ofN-GlO-AAF were: 3 rats with sarcomas at the site of injection, 3 rats with benign mammary tumors, and 1 rat with a thymoma. By 20 months the rats injected with the cupric salt of N-G10-AAF had: 1 sarcoma at the injection site, 1 splenic lymphoma, 2 mammary tumors (1 malignant and 1 benign), and 1 hemangiopericy toma. By 20 months the tumors resulting from injection of the triacetyl methyl ester of N-GlO-AAF were: 8 rats with sarcoma at the site of injection, 1 reticulum cell sarcoma of the spleen, and 1 cholangiorna. The only tumor evident by 20 months in the tricaprylin-injected con trol rats was 1 benign mammary …