The present study investigated the effect of L-type calcium channel mo
dulators on stimulant-induced locomotor activity. The L-channel activa
tor, (+/-)BayK8644, produced a marked, long-lasting enhancement of coc
aine-induced activity, while having no effect on amphetamine hyperacti
vity. Nicardipine reduced cocaine hyperactivity but had no effect on t
he amphetamine response.