Mechanism for the Vascular Relaxation Induced by Butanol Extract of Agrimonia pilosa

The butanol extracts of Agrimonia pilosa(BAP) induced dose-dependent vascular relaxation of phenylephrine-pre-contracted aorta, which was abolished by removal of functional endothelium. Pretreatment of the endothelium-intact aortic tissues with N∨G-nitro-L-arginine methyl ester(L-NAME) and 1H-[1,2,4,]-oxadiazole-[4,3,-α]-quinoxalin-1-one(ODQ) inhibited the relaxation induced by BAP. BAP-induced vascular relaxation was also markedly attenuated by addition of verapamil, while the relaxant effect of BAP was not blocked by indomethacine, glibenclamide, tetraethylammonium (TEA), atropine, or propranolo.