[Modulation of electrical responses of endothelial cells by nicotinic cholinoreceptors].
Because the sustained component of hyperpolarization of endothelial cells evoked by acetylcholine in isolated rat aorta may partially be mediated by the reversed Na(+)-Ca(2+) exchanger and Na(+)-K(+) ATPase, the mechanisms which transport Na(+) out of cells, we compared the electrical responses of endothelial cells from isolated rat aorta to acetylcholine with other Ca(2+) mobilizing agents and studied the effect of nicotine on endothelial membrane potential in order to asses the functional activity of nicotinic cholinoreceptors. Ca(2+) ionophores A23187 and ionomycin, as well as inhibitors of endoplasmic reticulum Ca(2+) ATPase cyclopiazonic acid and 2,5-di-tert-butylhydroquinone evoked a short-lived hyperpolarization which turned to a sustained depolarization of endothelial cells, a time course that substantially differed from that evoked by acetylcholine. Nicotine evoked a Na+ dependent depolarization of endothelial cells confirming functional activity ofnicotinic cholinoreceptors in rat aortic endothelial cells. The results suggest that stimulation of Na+ permeant nicotinic receptors by acetylcholine may contribute to sustained hyperpolarizatiom via stimulation of Na+ extrusion mechanisms.
Bondarenko
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Sahach
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D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects*; D009538:Nicotine / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D051381:Rats; D011978:Receptors, Nicotinic / Q000378:metabolism / Q000502:physiology*; D019831:Sodium-Calcium Exchanger / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D011978:Receptors, Nicotinic; D019831:Sodium-Calcium Exchanger; D009538:Nicotine; D000254:Sodium-Potassium-Exchanging ATPase; D000109:Acetylcholine