title: [Modification of phenylephrine induced contraction of human vessel rings by L-arginine and L-arginine methyl ester].
abstract: BACKGROUND
  Endothelial dysfunction is associated to a lower production of nitric oxide and a reduction of endothelium mediated vasodilation.
  
  
  OBJECTIVE
  To study the effects of pharmacological agents that modify nitric oxide synthetase (NOS) activity on tension changes induced by phenylephrine in rings of internal mammary and radial arteries and saphenous vein.
  
  
  METHODS
  Vessel rings of 7 to 10 mm length were obtained from 32 patients subjected to coronary vascular surgery Fourteen samples of radial artery, 12 samples of internal mammary artery and 15 samples of saphenous vein were obtained. A maximal contraction was induced with KC1 and dose response curves for phenylephrine (FE) in the absence or presence of L-arginine and L-arginine methyl ester (L-NAME), were constructed.
  
  
  RESULTS
  The tension induced by FE in internal mammary artery and saphenous vein reached a maximum, near 90% of 80 mM KCl-induced contraction, but in the radial artery, it reached a maximum of 63% (p <0.05). In all vessels, the dose response curves were significantly shifted to the right by L-arginine and to the left by L-NAME.
  
  
  CONCLUSIONS
  Pre-incubation of human rings with L-ARG or L-NAME, changed the response to FE induced contraction, which may be related to different degrees of endothelial nitric oxide production or NO sensitivity. The basal NO production in radial artery seems to be larger than the other vessels.
authors.affiliation: Centro Cardiovascular, Hospital Clínico, Universidad de Chile, Santiago, Chile. jprieto@med.uchile.cl
authors.forename: Juan C
authors.initials: JC
authors.lastname: Prieto
authors.forename: Gianni
authors.initials: G
authors.lastname: Pinardi
authors.forename: Jaime
authors.initials: J
authors.lastname: Zamorano
authors.forename: Ernesto
authors.initials: E
authors.lastname: Larraín
authors.forename: Cristian
authors.initials: C
authors.lastname: Bermúdez
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Castillo
authors.forename: Verónica
authors.initials: V
authors.lastname: Cisternas
authors.forename: Hugo F
authors.initials: HF
authors.lastname: Miranda
mesh_terms: D001120:Arginine / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D008323:Mammary Arteries / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000201:enzymology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D010656:Phenylephrine / Q000494:pharmacology*; D017534:Radial Artery / Q000187:drug effects; D012501:Saphenous Vein / Q000187:drug effects; D014661:Vasoconstriction; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D001120:Arginine; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester