title: Effects of magnesium on human umbilical arteries: role of intracellular calcium stores.
abstract: The purpose of this investigation on human umbilical arteries was: (1) to analyze the effects of magnesium (Mg2+) in the prevention of contractions induced by 5-hydroxytryptamine (5-HT), KCl, Bay K 8644 and BaCl2; (2) to determine whether the presence of Mg2+ could modulate the response to caffeine in Ca2+-free medium at 25 and 37 degreesC, and (3) to examine the influence of Mg2+ and temperature in the release of intracellular calcium induced by 5-HT in Ca2+-free medium. Human umbilical arteries were dissected and mounted in organ baths for isometric measurement of force. Our results showed: (1) Mg2+ is a potent inhibitor of smooth muscle contraction of human umbilical arteries caused by 5-HT, KCl, Bay K 8644 and BaCl2, and that this effect might be due to the inhibition of the transmembrane calcium influx. (2) The relaxant effect of Mg2+ did not seem to be mediated by a blockade of the release of calcium from an intracellular store. (3) Moreover, our results suggest an effect of temperature independent from the action of Mg2+ on 5-HT-induced contraction.
authors.affiliation: Laboratoire de Physiologie et Pharmacologie Cardiovasculaire, Centre Hospitalier, Saint-Germain-en-Laye, France.
authors.forename: A
authors.initials: A
authors.lastname: Tiritilli
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D017609:Barium Compounds / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism* / Q000502:physiology; D002120:Calcium Channel Agonists / Q000494:pharmacology; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D004347:Drug Interactions; D005260:Female; D006801:Humans; D008274:Magnesium / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism; D012702:Serotonin Antagonists / Q000494:pharmacology*; D013696:Temperature; D014469:Umbilical Arteries / Q000187:drug effects / Q000378:metabolism
chemical_list: D017609:Barium Compounds; D002120:Calcium Channel Agonists; D000697:Central Nervous System Stimulants; D002712:Chlorides; D012702:Serotonin Antagonists; C024986:barium chloride; D002110:Caffeine; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D008274:Magnesium; D002118:Calcium