title: Differential effects of transdermal estradiol and sequential progestogens on impedance to flow within the uterine arteries of postmenopausal women.
abstract: OBJECTIVE
  To investigate the relationship between estradiol (E2), progestogen, and impedance to blood flow in the uterine artery.
  
  
  METHODS
  Twelve postmenopausal women treated for two cycles with transdermal E2, 0.05 mg/d, with either norethindrone acetate, 0.7 mg, or medroxyprogesterone acetate, 10 mg added sequentially.
  
  
  METHODS
  Transvaginal ultrasonography and color flow imaging were used to measure the pulsatility index in the uterine arteries before and during the E2-only and combined E2/progestogen phases.
  
  
  RESULTS
  The mean pulsatility index fell to 53% of its pretreatment value within 12 days E2 administration (P < or = 0.0001) and was 66% of its pretreatment value in the combined phase (P < 0.005). Similar changes were seen in cycle 2. Time since menopause was correlated with the pretreatment pulsatility index (r = 0.674, P < 0.05) and change in pulsatility index on treatment (r = 0.856, P < 0.001).
  
  
  CONCLUSIONS
  Gonadal hormones have a profound effect on arterial tone in postmenopausal women; this action may help explain some of the beneficial effects of estrogen on arterial disease risk.
authors.affiliation: Academic Department of Obstetrics and Gynaecology, King's College School of Medicine and Dentistry, London, United Kingdom.
authors.forename: T C
authors.initials: TC
authors.lastname: Hillard
authors.forename: T H
authors.initials: TH
authors.lastname: Bourne
authors.forename: M I
authors.initials: MI
authors.lastname: Whitehead
authors.forename: T B
authors.initials: TB
authors.lastname: Crayford
authors.forename: W P
authors.initials: WP
authors.lastname: Collins
authors.forename: S
authors.initials: S
authors.lastname: Campbell
mesh_terms: D000279:Administration, Cutaneous; D001158:Arteries / Q000000981:diagnostic imaging / Q000187:drug effects / Q000502:physiology; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008593:Menopause / Q000502:physiology*; D011372:Progestins / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D011673:Pulsatile Flow / Q000187:drug effects*; D014463:Ultrasonography; D014599:Uterus / Q000098:blood supply*
chemical_list: D011372:Progestins; D004958:Estradiol