Stimulation of D-2 dopamine receptors decreases the evoked in vitro release of [3H]acetylcholine from rat neostriatum: role of K+ and Ca2+.
Reportedly, stimulation of D-2 dopamine receptors inhibits the depolarization-induced release of acetylcholine from the neostriatum in a cyclic AMP-independent manner. In the present study, we investigated the role of K+ and Ca2+ in the D-2 receptor-mediated inhibition of evoked [3H]acetylcholine release from rat striatal tissue slices. It is shown that the D-2 receptor-mediated decrease of K+-evoked [3H]acetylcholine release is not influenced by the extracellular Ca2+ concentration. However, increasing extracellular K+, in the presence and absence of Ca2+, markedly attenuates the effect of D-2 stimulation on the K+-evoked [3H]acetylcholine release. Furthermore, it is shown that activation of D-2 receptors in the absence of Ca2+ also inhibits the veratrine-evoked release of [3H]acetylcholine from rat striatum. These results suggest that the D-2 dopamine receptor mediates the decrease of depolarization-induced [3H]acetylcholine release from rat striatum primarily by stimulation of K+ efflux (opening of K+ channels) and inhibition of intracellular Ca2+ mobilization.
Drukarch
B
B
Department of Neurology, Medical Faculty, Free University, Amsterdam, The Netherlands.
Schepens
E
E
Schoffelmeer
A N
AN
Stoof
J C
JC
D000109:Acetylcholine / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology / Q000502:physiology*; D003342:Corpus Striatum / Q000378:metabolism*; D015259:Dopamine Agents / Q000494:pharmacology; D004873:Ergolines / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D011188:Potassium / Q000494:pharmacology / Q000502:physiology*; D019257:Quinpirole; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000502:physiology*; D017448:Receptors, Dopamine D2; D013268:Stimulation, Chemical; D014316:Tritium; D014702:Veratrine / Q000494:pharmacology
D015259:Dopamine Agents; D004873:Ergolines; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D014316:Tritium; D019257:Quinpirole; D014702:Veratrine; D000109:Acetylcholine; D011188:Potassium; D002118:Calcium