Equal suppression of cerebellar Purkinje cell activity by amphetamine stereoisomers

The two amphetamine isomers were compared for their ability to reduce spontaneous activity of noradrenoceptive Purkinje cells in the rat cerebellum. The drugs were applied iontophoretically to eliminate peripheral and remote central effects. Responses of Purkinje neurons were summed over several cycles of alternating (+)- and (?)-amphetamine, and poststimulus time histograms were compared. Inhibitions of Purkinje cell discharge by the two isomers were not statistically different over a wide range of pipette resistances. These data, taken together with studies showing equal effects of the two isomers on noradrenergic release and reuptake blockade and on locus coeruleus neuronal firing, indicate equipotency of the two isomers in their actions on noradrenergic mechanisms.