DOPAMINE MODULATES THE AFTERHYPERPOLARIZATION IN NEOSTRIATAL NEURONS

INTRACELLULAR techniques were used to study the actions of dopaminergi c D-1 agonists on the afterhyperpolarization (AHP) that follows action potentials in rat neostriatal neurones. Dopamine or Cl-APB (10 mu M), or 1-10 mu M 6-Cl-PB all increased AHP amplitude. This effect was blo cked by 1 mu M SCH-23390, a D-1 antagonist, but not by 1 mu M sulpirid e, a D-2 antagonist. Both 500 mu M dibutyryl cAMP and 5 mu M Bay K 864 4 induced a similar AHP increase. Bay K 8644 occluded the effect of ag onists. The results suggest that the action of dopamine is mediated vi a the recently described protein kinase A enhancement of L-type Ca2+ c hannels. The results partially explain the decrease in firing frequenc y induced by dopamine and a possible site of antagonism with cholinerg ic modulation.