Autoradiography of intravenously injected ¹⁴C-nicotine indicates long-term retention in the respiratory tract.

Abstract

INVESTIGATIONS using autoradiography¹ to monitor the distribution in mice of ¹⁴C-labelled nicotine administered intravenously showed a consistently high concentration in the entire respiratory tract. A number of mice, some of them pregnant, were each given a single intravenous dose and then were autoradiographed at postinjection times varying between 5 min and 30 d. The injected dose was 0.4 µCi per g body weight (corresponding to 1.79 µg nicotine per g body weight) for the non-pregnant mice, and 0.25 µCi per g body weight (corresponding to 1.12 µg nicotine per g body weight) for the pregnant mice. The nicotine used was labelled in the methyl group (The Radiochemical Centre, Amersham, England, specific activity 73 µCi per mg⁻¹). Autoradiograms of whole body sagittal sections of the mice were made as described earlier¹. The times of exposure varied from 2 to 4 weeks.