title: Gender differences in wall shear-mediated brachial artery vasoconstriction and vasodilation.
abstract: OBJECTIVE
  We sought to investigate wall shear rate (WSR) and brachial artery diameter (BAD) changes simultaneously and to determine whether any gender differences exist in arterial reactivity.
  
  
  BACKGROUND
  Wall shear rate/stress and arterial reactivity are rarely assessed at the same time. Furthermore, flow-mediated vasoconstriction has received less attention than flow-mediated vasodilation in humans.
  
  
  METHODS
  A new noninvasive evaluation of WSR in the brachial artery, using multigated, pulsed Doppler velocimeter and a double-transducer probe moved and fixed by a robotic system, was developed.
  
  
  RESULTS
  The validity of the system was tested in vitro with calibrated tubes and showed a high correlation (r = 0.98, p < 0.001). In 10 men and 10 women of similar age, induction of low and high shear rates by forearm occlusion produced significant vasoconstriction and vasodilation, respectively. The time lag for maximal BAD changes was 3 min for vasoconstriction and 1 min for vasodilation. A greater half-time for vasodilation (96 +/- 6 for men and 86 +/- 12 s for women) than for shear rate (31 +/- 5 s for men and 34 +/- 4 s for women) was observed after discontinuation of occlusion. Relative BAD was correlated with WSR changes, showing a significantly higher slope in women than in men (p < 0.01). Moreover, a larger normalized arterial diameter per shear rate was observed for vasoconstriction (p < 0.01) and vasodilation (p < 0.01) in women than in men.
  
  
  CONCLUSIONS
  Shear-mediated arterial vasodilation and vasoconstriction were more pronounced in women than in men, suggesting different gender-related sensitivity in the regulation of large-artery vascular tone.
authors.affiliation: Centre de Médecine Préventive Cardiovasculaire, Institut National de la Santé et de la Recherche Médicale (INSERM), Hôpital Broussais, Paris, France. levenso@worldnet.fr
authors.forename: J
authors.initials: J
authors.lastname: Levenson
authors.forename: F
authors.initials: F
authors.lastname: Pessana
authors.forename: J
authors.initials: J
authors.lastname: Gariepy
authors.forename: R
authors.initials: R
authors.lastname: Armentano
authors.forename: A
authors.initials: A
authors.lastname: Simon
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001783:Blood Flow Velocity; D001916:Brachial Artery / Q000000981:diagnostic imaging*; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D012371:Robotics; D012737:Sex Factors; D012815:Signal Processing, Computer-Assisted; D014463:Ultrasonography; D014661:Vasoconstriction / Q000502:physiology; D014664:Vasodilation / Q000502:physiology