Choline induces Ca2+ entry in cultured sympathetic neurones isolated from rat superior cervical ganglion.
Choline has been shown to be a specific agonist at alpha7 nicotinic acetylcholine receptors, which are the most Ca(2+) permeable of the ionotropic receptor channels. Whole-cell patch recording combined with the measurement of intracellular free Ca(2+) concentration ([Ca(2+)](i), using Indo1, in cultured rat superior cervical ganglion neurones demonstrated that application of choline induced a slowly desensitizing inward current and increased [Ca(2+)](i). The effect was dose dependent with an EC(50) of 1.6 mM and an n(H) of 1.19. The relationship between the elevation of [Ca(2+)](i) (Delta[Ca(2+)](i)) and charge transfer analysed under various recording conditions showed that the Delta[Ca(2+)](i) induced by choline resulted from an influx of Ca(2+) through nicotinic acetylcholine receptors. The effect of choline on the membrane current and Delta[Ca(2+)](i) was not affected by either short application or pretreatment with alpha-bungarotoxin (50 nM) and methyllycaconitine (1 nM), two alpha7 nicotinic receptors antagonists. These results indicate that activation of non-alpha7 nicotinic acetylcholine receptors by choline significantly increases the Ca(2+) concentration in rat superior cervical ganglion neurones.
Seddik
Riad
R
Laboratoire de Neurophysiologie Cellulaire et Intégrée, Institut de Physiologie et de Chimie Biologique, CNRS UMR 7519, Université Louis Pasteur, 21 rue R. Descartes, 67084 Cedex, Strasbourg, France.
Bradaïa
Amyaouch
A
Trouslard
Jérôme
J
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000320:Adrenergic Fibers / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002794:Choline / Q000378:metabolism / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011978:Receptors, Nicotinic / Q000378:metabolism; D017783:Superior Cervical Ganglion / Q000187:drug effects* / Q000378:metabolism
D011978:Receptors, Nicotinic; D002794:Choline; D002118:Calcium