Microautoradiographic localization of bound metabolites in the nasal cavities of F344 rats treated with the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone.

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), the tobacco-specific N-nitrosamine, labeled with 14C on the carbonyl group, was given iv or orally to F334 rats. The animals were killed 4 hours later, and the localization of bound radioactivity in the nasal cavities was studied by light microscopic autoradiography. The strongest labeling was observed in the following groups of glands situated in the lamina propria mucosae: 1) Bowman's glands in the olfactory region, 2) the group of serous glands situated in the anterior half of the nasal septum beneath the respiratory epithelium, 3) the group of serous glands in the middle portion of the lateral wall of the nasal cavity, and 4) the lateral nasal gland (Steno's gland) located lateroventrally to the maxillary sinus. The group of mucous glands in the septum in connection with Jacobson's organ and the group of glands in connection with the dorsal, medial, and lateral parts of the maxillary sinus were not labeled. The olfactory and respiratory surface epithelia in the various parts of the nasal cavity were only weakly labeled. These results indicate that Bowman's glands, some serous glands, and Steno's glands are the principal sites where NNK is activated to alkylating species.