The effects of hormone replacement therapy on endothelial function in women with Turner's syndrome.
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.
Chan
N Norman
NN
Centre for Clinical Pharmacology, EURODIAB, Department of Epidemiology and Public Health, University College London, London, UK. nnkachan@aol.com
Vallance
Patrick
P
Colhoun
Helen M
HM
MacAllister
Raymond J
RJ
Hingorani
Aroon D
AD
Conway
Gerard S
GS
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
D004791:Enzyme Inhibitors; D014665:Vasodilator Agents; D019323:omega-N-Methylarginine; D019001:Nitric Oxide Synthase; D005996:Nitroglycerin; D001920:Bradykinin; D009638:Norepinephrine