Efflux of nicotine and its CNS metabolites from the nerve cord of the tobacco hornworm. Manduca sexta

The efflux of nicotine and its CNS metabolites from the ventral nerve cord were examined for the nicotine-resistant insect, Manduca sexta, and the nicotine-sensitive insect, Periplaneta americana. In both cases, highly reproducible efflux patterns were observed, but whereas 3 exponential components were resolved for Periplaneta, only two were found in Manduca. This difference was characteristic of all incubation periods tested (2, 5, 15, 30 and 60 min). The slowest component of efflux had a greater half-time in Manduca than Periplaneta (96.4 vs 61.0 min) for 30 min incubations, whereas the fastest components were very similar (0.9 vs 1.1 min for 30 min incubations). The kinetics of efflux from Manduca could be altered by decreasing the temperature or by adding to the washout medium such chemical agents as nicotine, atropine, N′-methylnicotinamide or dinitrophenol.