Disposition of3H‐Aflatoxin B1in Mice: Formation and Retention of Tissue Bound Metabolites in Nasal Glands

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Abstract
Whole‐body autoradiography with3H‐labelled aflatoxin B1(3H‐AFB1) in C57B1‐mice showed a pronounced accumulation and retention of radioactivity in some nasal glands. At long survival intervals the labelling of the nasal glands was much higher than that of the liver. Experimentsin vitroshowed a capacity of the nasal glands to form tissue‐bound3H‐AFB1‐metabolites. Incubations in the presence of glutathione decreased the levels of tissue‐bound3H‐AFB1‐metabolites both in the liver and in the nasal glands, but the decrease was more pronounced in the former than in the latter tissue. The3H‐AFB1‐metabolite‐binding to the nasal glandsin vitrowas inhibited by the cytochrome P‐450‐inhibitor metyrapone and by CO‐ and N2‐atmospheres indicating a cytochrome P‐450‐dependent bioactivation of the AFB1in these glands. Cytochrome P‐450 was shown to be present in the glands although at a much lower level than in the liver. The glands in the nose, which were shown to have this AFB1‐metabolizing capacity, were the lateral nasal gland (Steno's gland) situated ventrally and laterally to the maxillary sinus and the large group of glands in the lateral nasal wall ventrally to the ostium of the maxillary sinus. Our results also indicated an AFB1‐metabolizing capacity of the serous glands which are present in the anterior part of the nasal septum.