UPTAKE AND EFFLUX OF PARAQUAT-C-14 BY RAT LUNG SLICES - EFFECT OF IMIPRAMINE AND OTHER DRUGS

Paraquat [herbicide] accumulation by rat lung slices incubated at 10 or 100 .mu.M concentration was linear with time and the accumulated paraquat was noneffluxable. Imipramine (100 or 500 .mu.M) inhibited paraquat (10 .mu.M) uptake by 38 and 85%, respectively, and 500 .mu.M imipramine enhanced paraquat efflux by 40%. The combination of impaired uptake and enhanced efflux suggested the possibility that imipramine might reduce the toxicity of paraquat in intact animals. At the doses used, imipramine did not alter paraquat toxicity in vivo. Eleven other drugs [norepinephrine, 5-hydroxytryptamine, histamine, DL-propanolol, methamphetamine, paraquat, diphenhydramine, chlorpromazine, demethylimipramine, beta-phenethylamine, and spermine] were shown to inhibit uptake, but only 5 enhanced paraquat efflux.