OBJECTIVE: To observe vasodilation effect of EUL and its mechanism.METHOD: Isometric tension was recorded in isolated rat thoracic artery precontracted by noradrenaline (NE) to study the vasodilation effect of EUL, and to investigate the role of endothelial cell and vascular smooth muscle cell on vasodilation.RESULT: EUL was shown to significantly relax the endothelium-intact arteries precontracted by NE, relaxation had fall down on endothelium-denuded arteries. EUL did not affect the concentration-contraction curve of K+. NE and CaCl2 to shift to the right with an decrease in the maximum effective response, manifesting non-competitive antagonism (P <0. 01). The relaxant effect of EUL was significantly inhibited by pretreatment of endothelium-denuded aorta with potassium channel antagonist glibenclamide.CONCLUSION: EUL induces relaxation in rat aortic rings. The mechanisms may involve the endothelium and the activation of the potassium channels.
Animals Aorta, Thoracic