K(+)-evoked dopamine release depends on a cytosolic Ca2+ pool regulated by N-type Ca2+ channels.
Membrane depolarization evoked by 25-40 mM K+ elicited an immediate increase of somatic and neuritic [Ca2+]i in cultured dopaminergic neurons as measured by digital fluorescence microscope imaging. The rise of neuritic [Ca2+]i was inhibited by N-type but not L-type Ca2+ channel blockers, while the rise of somatic [Ca2+]i was prevented by both L- and N-type Ca2+ channel blockers. Similarly, depolarization-induced [3H]dopamine release was selectively attenuated by N-type Ca2+ channel blockers. The present results suggest that [3H]dopamine release from mesencephalic neuronal cell cultures relates to a Ca(2+)-dependent mechanism regulated by N-type channels located in the vicinity of the exocytotic sites within neuritic processes.
de Erausquin
G
G
FIDIA-Georgetown Institute for the Neurosciences, Georgetown University, Washington, DC 20007.
Brooker
G
G
Hanbauer
I
I
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D005260:Female; D008636:Mesencephalon / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008856:Microscopy, Fluorescence; D011188:Potassium / Q000494:pharmacology*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley
D015220:Calcium Channels; D011188:Potassium; D002118:Calcium; D004298:Dopamine