title: Diphasic effects of Astragalus membranaceus BUNGE (Leguminosae) on vascular tone in rat thoracic aorta.
abstract: This study was designed to investigate the effects of the aqueous ethanol extract of Astragalus membranaceus BUNGE (Leguminosae) on rat thoracic aorta. Isometric tension was recorded in response to drugs in organ bath. In endothelium-intact aortic rings, A. membranaceus extract induced a significant dose-dependent relaxation of the rings precontracted by phenylephrine, which could be inhibited by preincubation with L-N(omega)-nitro-arginine methyl ester or methylthioninium chloride. In endothelium-denuded ones, the extract could dose-dependently relax the rings contracted by phenylephrine, not by KCl; and it could also attenuate contractile response to phenylephrine, not to caffeine or phorbol-12,13-diacetate in Ca(2+)-free medium; but it failed to affect the CaCl(2)-induced enhancement of contractile response to phenylephrine in Ca(2+)-free medium. These results indicate that nitric oxide signaling and Ca(2+)-handling pathway are involved in the A. membranaceus extract-induced vasodilatation.
authors.affiliation: Department of Cardiology, The First Affiliated Hospital, College of Medicine, Zhejiang University, No. 79 Qingchun Street, Hangzhou 310-003, Zhejiang, P.R. China.
authors.forename: Bi-Qi
authors.initials: BQ
authors.lastname: Zhang
authors.forename: Shen-Jiang
authors.initials: SJ
authors.lastname: Hu
authors.forename: Li-Hong
authors.initials: LH
authors.lastname: Qiu
authors.forename: Qi-Xian
authors.initials: QX
authors.lastname: Shan
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.forename: Qiang
authors.initials: Q
authors.lastname: Xia
authors.forename: Ka
authors.initials: K
authors.lastname: Bian
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D007887:Fabaceae / Q000737:chemistry*; D066298:In Vitro Techniques; D007537:Isometric Contraction; D008297:Male; D009129:Muscle Tonus / Q000187:drug effects*; D010936:Plant Extracts / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D010936:Plant Extracts