Dopamine modulates the afterhyperpolarization in neostriatal neurones.
Intracellular techniques were used to study the actions of dopaminergic D1 agonists on the afterhyperpolarization (AHP) that follows action potentials in rat neostriatal neurones. Dopamine or Cl-APB (10 microM), or 1-10 microM 6-Cl-PB all increased AHP amplitude. This effect was blocked by 1 microM SCH-23390, a D1 antagonist, but not by 1 microM sulpiride, a D2 antagonist. Both 500 microM dibutyryl cAMP and 5 microM BayK 8644 induced a similar AHP increase. BayK 8644 occluded the effect of agonists. The results suggest that the action of dopamine is mediated via the recently described protein kinase A enhancement of L-type Ca2+ channels. The results partially explain the decrease in firing frequency induced by dopamine and a possible site of antagonism with cholinergic modulation.
Hernández-López
S
S
Departamento de Neurociencias, UNAM, México City, DF, México.
Bargas
J
J
Reyes
A
A
Galarraga
E
E
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002120:Calcium Channel Agonists / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology / Q000502:physiology*; D065127:Dopamine D2 Receptor Antagonists; D066298:In Vitro Techniques; D017072:Neostriatum / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017447:Receptors, Dopamine D1 / Q000819:agonists / Q000037:antagonists & inhibitors; D017448:Receptors, Dopamine D2 / Q000819:agonists
D002120:Calcium Channel Agonists; D065127:Dopamine D2 Receptor Antagonists; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D003994:Bucladesine; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D004298:Dopamine