title: [Endothelium-independent vasorelaxation of plant-derived estrogen biochanin A and its mechanism in rat aortic rings].
abstract: OBJECTIVE
  To investigate the mechanisms of vasodilatation of plant-derived estrogen biochanin A.
  
  
  METHODS
  Isolated aortic ring preparations from Sprague-Dawley rats were suspended in individual organ baths. The tension was measured isometrically.
  
  
  RESULTS
  Biochanin A at the range of 10(-9)-10(-4) mol/L provoked concentration-dependent and endothelium-independent relaxation of the rings constricted by phenylephrine (10(-5) mol/L). Biochanin A caused concentration-dependent relaxation of denuded rings precontracted with KCl (6 x 10(-2) mol/L). Glibenclamide (3 x 10(-6) mol/L), a selective inhibitor of ATP-sensitive potassium channels, and tetraethylammonium (5 x 10(-3) mol/L), a Ca2+ -activated K+ channel inhibitor, significantly attenuated the relaxation induced by biochanin A. The vasoconstriction induced by phenylephrine was decreased by biochanin A in Ca2+ -free medium.
  
  
  CONCLUSIONS
  The endothelium-independent relaxation of thoracic aorta induced by biochanin A might be mediated by ATP-sensitive K+ channels, Ca2+ -activated K+ channels and intracellular Ca2+ release from sarcoplasmic reticulum.
authors.affiliation: Department of Physiology, Zhejiang University School of Medicine, Hangzhou 310031, China.
authors.forename: Hui-ping
authors.initials: HP
authors.lastname: Wang
authors.forename: Fu-yu
authors.initials: FY
authors.lastname: Qiu
authors.forename: Cheng
authors.initials: C
authors.lastname: Chen
authors.forename: Meng-hui
authors.initials: MH
authors.lastname: Zhao
authors.forename: Yuan
authors.initials: Y
authors.lastname: Lu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Xia
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D019833:Genistein / Q000494:pharmacology*; D066298:In Vitro Techniques; D054086:KATP Channels / Q000378:metabolism; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D054086:KATP Channels; D019833:Genistein; C004541:biochanin A