title: Endothelial-mediated microcirculatory responses to an acute estradiol test are influenced by time since menopause, cumulative hormone exposure, and vasomotor symptoms.
abstract: OBJECTIVE
  The aim of this study was to determine which factors could influence microcirculatory responses to an acute estradiol test during postmenopause.
  
  
  METHODS
  Dynamic nailfold videocapillaroscopy was performed in 68 healthy 34- to 70-year-old postmenopausal women before and 1 hour after administration of 300 mug nasal estradiol. Red blood cell velocity (RBCV; mm/s) at rest and after the release of 60-second arterial occlusion (RBCVmax; mm/s) and time to reach it (TRBCVmax; s) were correlated to clinical and laboratory data.
  
  
  RESULTS
  After estradiol administration, RBCV and RBCVmax increased by 13.4% and 9.4%, respectively, and TRBCVmax decreased by 29.1% (P = 0.0001 for all). These changes were not associated to the women's age but rather to time since menopause (P = 0.04; r = 0.245) and previous duration of hormone therapy (P = 0.03; r = 0.324). Past users of oral contraceptives presented higher velocities but smaller increases compared with never users (12.4% vs 17.7%, P = 0.022, for RBCV and 8.4% vs 13.7%, P = 0.028, for RBCVmax), and triglyceride levels were negatively associated to velocity increases (P = 0.05 and r = -0.243 for RBCV and P = 0.03 and r = -0.261 for RBCVmax) after estradiol administration. Previous smokers showed a smaller reduction in TRBCVmax, associated directly to total estimated number of smoked cigarettes (P = 0.03; r = -0.468). The reduction in TRBCVmax was also inversely related to the intensity of current vasomotor symptoms (P = 0.04; r = -0.252).
  
  
  CONCLUSIONS
  Changes in RBCVs and TRBCVmax after estradiol administration indicate an increase in endothelial-dependent vasodilatation and vascular elasticity, respectively. Moreover, maintenance of endothelial responsiveness depends on cumulative exposure to sex steroids, duration of hormone deprivation, and triglyceride levels. Past smoking and current vasomotor symptoms could be associated to microvascular wall stiffness/elasticity.
authors.affiliation: State University of Rio de Janeiro, Rio de Janeiro, Brazil. rclapauch@uol.com.br
authors.forename: Ruth
authors.initials: R
authors.lastname: Clapauch
authors.forename: Anete S
authors.initials: AS
authors.lastname: Mecenas
authors.forename: Priscila A
authors.initials: PA
authors.lastname: Maranhão
authors.forename: Eliete
authors.initials: E
authors.lastname: Bouskela
mesh_terms: D000281:Administration, Intranasal; D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D003276:Contraceptives, Oral / Q000008:administration & dosage; D004730:Endothelium, Vascular / Q000502:physiology; D004912:Erythrocytes / Q000502:physiology; D004958:Estradiol / Q000008:administration & dosage*; D004967:Estrogens / Q000008:administration & dosage*; D005260:Female; D020249:Hormone Replacement Therapy; D019584:Hot Flashes / Q000503:physiopathology; D006801:Humans; D008593:Menopause; D008833:Microcirculation / Q000502:physiology*; D018715:Microscopy, Video; D008875:Middle Aged; D012907:Smoking / Q000503:physiopathology; D013997:Time Factors; D014280:Triglycerides / Q000097:blood; D014664:Vasodilation / Q000502:physiology
chemical_list: D003276:Contraceptives, Oral; D004967:Estrogens; D014280:Triglycerides; D004958:Estradiol