Vasodilative Ettects Of The Water Extract Of The Siegesbeckia Glabrescens On Rat Thoracic Aorta

Purpose:To investigate the effect of the water extract of Siegesbeckia glabrescens Makino in relaxing isolated thoracic aorta rings in rats and discuss its possible mechanism.Methods:Tension was measured to evaluate the vasodilation effect of the water extract of Siegesbeckia glabrescens Makino on rat endothelium-intact and endothelium-denuded thoracic aorta rings preconstricted by 1.0 μmol.L-1 phenylephrine(PE) and KC1 (60mM).The nitric oxide synthase inhibitor N-nitro-L-arginine methy ester(L-NAME),guanylyl cyclase inhibitor methylene blue.cyclooxygenase inhibitor indomethacin,were used to the effects of vasodilation of the water extract of Siegesbeckia glabrescens Makino.Results:The the water extract of Siegesbeckia glabrescens Makino for integrated endothelium thoracic aorta ring of rats in vitro had a concentration-dependent dilation,and pretreatment with the L-NAME and methylene blue could obviously inhibit the vasodilation.In the absence of Ca2+,pre-incubated the water extract of Siegesbeckia glabrescens Makino showed had no effect in relaxing phenylephrine contraction.Conclusions:The water extract of Siegesbeckia glabrescens Makino has endothelium-dependent vasodilative effects of thoracic aorta ring of rats in vitro,and the effects may be mediated by No-cGMP pathway.