title: The effects of hormone replacement therapy on endothelial function in women with Turner's syndrome.
abstract: OBJECTIVE
  To examine the effect of hormone replacement therapy (HRT) on endothelial function of forearm resistance vessels in women with Turner's syndrome.
  
  
  METHODS
  Subjects were studied on three occasions: on their usual HRT (study 1), then after 6 weeks off HRT (study 2) and finally after a further 6 weeks on HRT (study 3).
  
  
  METHODS
  Seven young women with Turner's syndrome were studied.
  
  
  METHODS
  Forearm blood flow in response to intrabrachial infusion of bradykinin, 10, 30, 100 pmol/min (endothelium-dependent vasodilator), glyceryl trinitrate, 4, 8, 16 nmol/min (GTN; endothelium-independent vasodilator), noradrenaline, 60, 120, 240 pmol/min (NA, alpha-adrenergic receptor agonist) and NG-monomethyl-l-arginine, 1, 2, 4 micromol/min (L-NMMA; NO synthase inhibitor) was assessed by bilateral venous plethysmography.
  
  
  RESULTS
  The vasodilator response to bradykinin, expressed as the within-subject mean difference in area under the dose-response curve between study 2 and study 1, was significantly diminished (-744.2 +/- 287.2, P = 0.04) but improved 6 weeks after HRT recommencement. However, there was no significant change in response to GTN (between study 2 and study 1, 189.5 +/- 247.8, P = 0.47). The vasoconstrictor response to L-NMMA was also diminished in study 2 when compared to study 1 (-100.4 +/- 35.4, P = 0.039) and was restored after HRT was recommenced (between study 3 and study 2, 117.5 +/- 69.3, P = 0.17) whereas there was no significant difference in response to NA between study 2 and study 1 (76.7 +/- 50.6, P = 0.18) or study 3 and study 2 (-70.8 +/- 71.1, P = 0.38).
  
  
  CONCLUSIONS
  HRT improves endothelial function in women with Turner's syndrome.
authors.affiliation: Centre for Clinical Pharmacology, EURODIAB, Department of Epidemiology and Public Health, University College London, London, UK. nnkachan@aol.com
authors.forename: N Norman
authors.initials: NN
authors.lastname: Chan
authors.forename: Patrick
authors.initials: P
authors.lastname: Vallance
authors.forename: Helen M
authors.initials: HM
authors.lastname: Colhoun
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: MacAllister
authors.forename: Aroon D
authors.initials: AD
authors.lastname: Hingorani
authors.forename: Gerard S
authors.initials: GS
authors.lastname: Conway
mesh_terms: D000328:Adult; D019540:Area Under Curve; D001920:Bradykinin; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000503:physiopathology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015914:Estrogen Replacement Therapy; D005260:Female; D005542:Forearm / Q000098:blood supply; D006801:Humans; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D005996:Nitroglycerin; D009638:Norepinephrine; D012039:Regional Blood Flow / Q000187:drug effects; D014424:Turner Syndrome / Q000188:drug therapy / Q000503:physiopathology*; D014665:Vasodilator Agents; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D014665:Vasodilator Agents; D019323:omega-N-Methylarginine; D019001:Nitric Oxide Synthase; D005996:Nitroglycerin; D001920:Bradykinin; D009638:Norepinephrine