title: Deuterium oxide reduces agonist and depolarization-induced contraction of rat aortic rings.
abstract: The influence of deuterium oxide (D2O) on calcium-dependent vascular smooth muscle contraction was investigated. The effect of D2O on receptor-operated calcium channels was investigated with phenylephrine-induced contraction in the rat aortic ring preparation. D2O depressed the contraction response in a dose-dependent manner with 50% inhibition of maximum contraction observed with 60% D2O. The effect of 60% D2O on phenylephrine-induced contraction was reversible and not dependent on an intact endothelium. Sixty percent D2O also reduced potassium chloride induced contractions by 50%, indicating an effect on voltage-operated calcium channels. Studies with Bay K 8644, and L-type calcium channel activator, confirm an effect on utilization of extracellular calcium sources and on the voltage-operated calcium channel. Sixty percent D2O also depressed a calcium contraction dose-response curve by approximately 25%. Likewise, a change in the pD2' for nifedipine in the presence of D2O may indicate an effect on the nifedipine binding site and (or) the voltage-dependent calcium channel. Further studies were performed to determine whether the D2O effects were nonspecific or selective effects on the receptor- and voltage-operated calcium channels. Sucrose-induced contaction in the presence of 60% D2O was found to be inhibited by approximately 50%. D2O similarly affected isoprenaline relaxation, which would suggest a nonspecific D2O effect on the vascular smooth muscle contractile process.
authors.affiliation: Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada.
authors.forename: T M
authors.initials: TM
authors.lastname: McWilliam
authors.forename: A
authors.initials: A
authors.lastname: Liepins
authors.forename: A J
authors.initials: AJ
authors.lastname: Rankin
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D002118:Calcium / Q000502:physiology; D003903:Deuterium / Q000494:pharmacology*; D017666:Deuterium Oxide; D004730:Endothelium, Vascular / Q000502:physiology; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009543:Nifedipine / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D014867:Water / Q000494:pharmacology*
chemical_list: D014867:Water; D010656:Phenylephrine; D009569:Nitric Oxide; D011189:Potassium Chloride; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D003903:Deuterium; D009543:Nifedipine; D017666:Deuterium Oxide; D007545:Isoproterenol; D002118:Calcium