MASTOPARAN ACTIVATION OF DOPAMINE-MODULATED K+ CHANNELS ON RAT STRIATAL NEURONS

COUPLING mechanisms between a D-2-like dopamine receptor and an 85 pS K+ channel on freshly dissociated rat caudate-putamen neurons were stu died using cell-attached patch-clamp electrophysiology. Channel curren ts were observed in the absence of dopamine receptor agonists when mas toparan, an activator of certain guanyl nucleotide binding proteins (G -proteins), was applied via the patch pipette. Channel current-voltage relationships and open probabilities observed with mastoparan were in distinguishable from those obtained with dopaminergic agonists. Alamet hicin, which mimics the membrane-perturbing but not the G-protein acti vating properties of mastoparan, did not activate the channel, suggest ing that non-specific effects of mastoparan were unlikely to account f or this effect. Our results indicate that coupling between the D-2 dop amine receptor and this K+ channel may involve a mastoparan-sensitive G-protein.