Autoradiography of [14C]N-nitrosodiethanolamine in Sprague-Dawley rats.

Whole-body autoradiography in Sprague-Dawley rats injected i.v. with [14C]N-nitrosodiethanolamine ([14C]NDELA) showed a localization of tissue-bound radioactivity in the liver and the nasal olfactory mucosa. Microautoradiography of the nasal olfactory mucosa showed the highest labelling over the subepithelial glands (Bowman's glands) in the lamina propria mucosae. Experiments in vitro showed a capacity of the liver and the nasal mucosa to form 14CO2 from the [14C]NDELA. Most of the injected [14C]NDELA was recovered in the urine in a non-metabolized form. A small proportion of the dose was exhaled as 14CO2. The target tissues for the NDELA carcinogenesis in Sprague-Dawley rats are the liver and the nasal mucosa. Our results indicate that a bioactivation of the NDELA will take place in the nasal mucosa, as well as in the liver.