Mastoparan activation of dopamine-modulated K+ channels on rat striatal neurons.
Coupling mechanisms between a D2-like dopamine receptor and an 85 pS K+ channel on freshly dissociated rat caudate-putamen neurons were studied using cell-attached patch-clamp electrophysiology. Channel currents were observed in the absence of dopamine receptor agonists when mastoparan, 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 indistinguishable from those obtained with dopaminergic agonists. Alamethicin, which mimics the membrane-perturbing but not the G-protein activating properties of mastoparan, did not activate the channel, suggesting that non-specific effects of mastoparan were unlikely to account for this effect. Our results indicate that coupling between the D2 dopamine receptor and this K+ channel may involve a mastoparan-sensitive G-protein.
Greif
G J
GJ
Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, USA.
Lin
Y J
YJ
Freedman
J E
JE
D000818:Animals; D002421:Caudate Nucleus / Q000502:physiology; D004298:Dopamine / Q000494:pharmacology*; D018491:Dopamine Agonists; D004873:Ergolines / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins; D008297:Male; D017072:Neostriatum / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010455:Peptides; D015221:Potassium Channels / Q000502:physiology*; D011699:Putamen / Q000502:physiology; D019257:Quinpirole; D051381:Rats; D017207:Rats, Sprague-Dawley; D014862:Wasp Venoms / Q000494:pharmacology*
D018491:Dopamine Agonists; D004873:Ergolines; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D015221:Potassium Channels; D014862:Wasp Venoms; D019257:Quinpirole; C037500:mastoparan; D004298:Dopamine