摘要：This study was designed to investigate the effects of the aqueous ethanol extract of Astragalus membranaceus B UNGE (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 (ω)-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 Ca2+-free medium; but it failed to affect the CaCl2-induced enhancement of contractile response to phenylephrine in Ca2+-free medium. These results indicate that nitric oxide signaling and Ca2+-handling pathway are involved in the A. membranaceus extract-induced vasodilatation.
