title: The Effect of Eqoul, a Metabolite of Isoflavone, on Endothelial Cell-independent Vasodilatation of Human Uterine Artery In Vitro.
abstract: BACKGROUND
  The purpose of this study is to investigate 1) whether equol has the direct modulation on vascular tone of endothelium-denuded human uterine artery, and 2) if present, whether this equol-induced modulation of vascular tone is mediated by intracellular calcium modulation through Ca(2+) & K(+) channels on vascular smooth muscle cell membrane.
  
  
  METHODS
  The uterine arteries were obtained at the time of hysterectomy from 15 women. The uterine smooth muscles were pretreated with phenylephrine, 10(-5) M & high KCl solution 70 mM. The equol at 6 different concentrations from 10(-11) to 10(-6) M were used for the evaluation of modulatory action of equol on precontracted vascular smooth. The cumulative concentration-response for equol were determined on phenylephrine-induced contractions and compared with the results without pretreatment.
  
  
  RESULTS
  Equol 10(-11) to 10(-6) M in concentration showed relaxation effect on vascular smooth muscle contraction which was induced by phenylephrine 10(-5) M. This relaxation effect of equol was dose-dependent. Equol in same concentrations showed no significant effects on vascular smooth muscle contraction induced by high KCI solution. Phenylephrine-induced contraction was markedly reduced from 10(-7) to 10(-4) M in concentration by pretreatment of equol, but high KCI-induced contraction was not affected by pretreatment of equol.
  
  
  CONCLUSIONS
  This vasodilatation effect of equol may be induced by calcium antagonistic action, which was mediated through antagonistic action for receptor-dependent Ca(2+) channel, but not for voltage-dependent Ca(2+) channel. As far as we know, this is the first report of phytoestrogen equol on vascular reactivity of human vessels.
authors.affiliation: Department of Obstetrics and Gynecology, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Jeong Yuen
authors.initials: JY
authors.lastname: Kim
authors.affiliation: Department of Physiology, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Moo Yeol
authors.initials: MY
authors.lastname: Lee
authors.affiliation: Department of Obstetrics and Gynecology, Chung-Ang University College of Medicine, Seoul, Korea.
authors.forename: Hyoung Moo
authors.initials: HM
authors.lastname: Park
keywords: Equol; Mucsle smooth; Vasodilation