Single K+ channels activated by D2 dopamine receptors in acutely dissociated neurons from rat corpus striatum.

Corpus striatum neurons acutely dissociated from the brains of young adult rats had membrane surfaces suitable for G omega-seal recording. Whole-cell current-clamp and voltage-clamp recordings indicated that the cells remained electrically excitable after dissociation. Cell-attached recordings frequently revealed single-channel openings in the presence of dopamine or of the D2 dopamine agonist quinpirole. Channel openings were rarely or never observed in the absence of drugs or in the presence of quinpirole plus the dopamine antagonist haloperidol. The D2 antagonist spiperone was more potent at blocking the appearance of the channel than was the D1 antagonist SCH-23390. The channel reversal potential varied with the extracellular K+ concentration as predicted by the Nernst equation. The channel current-voltage relationship was linear, with a conductance of approximately equal to 85 pS in the presence of 140 mM KCl. These results are consistent with the opening of single K+ channels following D2 dopamine receptor activation.