title: Evidence of K and Ca channels in endothelial cells of human allantochorial placental vessels.
abstract: Presence of ionic channels was evaluated in human endothelial cells (ECs) from allantochorial placental vessels by the measure of the membrane potential, the main factor of the excitation-contraction coupling. To characterize endothelial cell channels, vasoactive and vasorelaxant agents and channels blockers were used. In predepolarized cells by high-K+ concentration, the voltage-dependent K+ channels (Kdf) were blocked. Acetylcholine, sodium nitroprusside and isoproterenol hyperpolarized the predepolarized-high K+ ECs. This hyperpolarization was inibited by charybdotoxin (a blocker of big Ca(2+)-activated K+ channels) or/and by tetraethylammonium and was insensitive to glibenclamide (a blocker of ATP-sensitive K+ channels). Serotonin depolarized ECs and the depolarization was inibited by nifedipine, a blocker of voltage-gated Ca2+ channels. These results indicated that membrane potential of human placental allantochorial ECs was regulated by voltage-gated, C(2+)-sensitive K+ channels and by voltage-gated Ca2+ channels.
authors.affiliation: Physiology and Physiopathology Laboratory, University Pierre et Marie Curie, Paris, France.
authors.forename: Andrée
authors.initials: A
authors.lastname: Guiet-Bara
authors.forename: Michel
authors.initials: M
authors.lastname: Bara
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000482:Allantois / Q000098:blood supply*; D001808:Blood Vessels / Q000502:physiology*; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002823:Chorion / Q000098:blood supply*; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D005905:Glyburide / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009599:Nitroprusside / Q000494:pharmacology; D010920:Placenta / Q000098:blood supply*; D011188:Potassium / Q000494:pharmacology; D015221:Potassium Channels / Q000502:physiology*; D011247:Pregnancy; D019789:Tetraethylammonium / Q000494:pharmacology
chemical_list: D015220:Calcium Channels; D015221:Potassium Channels; D009599:Nitroprusside; D019789:Tetraethylammonium; D007545:Isoproterenol; D000109:Acetylcholine; D011188:Potassium; D005905:Glyburide