Abstract

The study was designed to investigate a number of compounds with respect to their characteristies of potentiation of norepinephrine. Included were some central stimulants, desipramine-like antidepressants and tranquilizers. The experiments were carried out on the isolated vas deferens of the rat which was found to be the most suitable of various isolated preparations for the study of norepinephrine potentiation in vitro. The characteristics measured were the concentrations required for 1 ) threshold potentiation, 2) maximal potentiation, 3) reversal of potentiation and the degree of maximal potentiation. Marked quantitative differences but no qualitative differences were found between time central stimulants (cocaine, methylphenidatc, pipradrol, phenmetrazine) and the antidepressants. The batter produced maximal potentiation in concentrations at which the former had minimal or no effect. Among the desipramine-like chemical structures the N-monomethyl was more potent than the corresponding N-dimethyl. It is pointed out that the hypothesis which attempts to relate antidepressa. sant activity and potentiation of norepinephrine at present fails to account for the differences in the central effects of antidepressants and psychostimulants.