Objective:To study the effect of gastrodin on isolated thoracic aorta rings of rats and to investigate the potential mechanism.Methods:A perfusion model of isolated thoracic aorta rings of rats was applied.The effect of cumulative gastrodin(5,50,100,150,200,and 250 μmol/L) on endothelium-intact aorta rings was investigated.The same procedure was applied to observe the effect of gastrodin on endotheliumintact/denuded aorta rings pre-contracted with 10~(-8) mol/L phenylephrine hydrochloride(PE).The aorta rings incubated by 200 mmol/L gastrodin in the Ca~(2+)-free(K-H) solution was contracted by using PE.The effect of 200 mmol/L gastrodin on endothelium-denuded aorta rings pre-contracted with 60 mmol/L KCI was also observed.Results:Compared with the denuded gastrodin group,the intact gastrodin group could significantly relax the PE-contracted aorta rings(P<0.01).In Ca~(2+)-free(K-H) solution KHS,the PE-induced contraction rate of aorta rings pre-incubated by gastrodin was 6.5%±0.7%,which was significantly less than the control group(11.8%±0.9%,P<0.01).However,after 3 mmol/L CaCI_2 was added,the Ca~(2+)-induced contraction in the gastrodin group(51.7%±2.4%) was similar to that in the control group(49.8%±2.8%).The contractile rate of rings in the KCI-contracted gastrodin group(96.3%± 0.6%) was not significantly different from that in the control group(96.8%±1.2%).Conclusions:Gastrodin has the effect of vasorelaxation on isolated thoracic aorta rings of rats.The mechanism of the vasorelaxation of gastrodin may mainly work through the inhibition of inositol 1,4,5-trisphosphosphate receptor on the sarcoplasmic reticulum of the arterial smooth muscle,which leads to the reduction of the Ca~(2+) released from the sarcoplasmic reticulum. Objective: To study the effect of gastrodin on isolated thoracic aorta rings of rats and to investigate the potential mechanism. Methods: A perfusion model of isolated thoracic aorta rings of rats was applied. The effect of cumulative gastrodin (5, 50, 100, 150, 200 and 250 μmol / L) on endothelium-intact aorta rings was investigated.The same procedure was applied to observe the effect of gastrodin on endothelium in contact / denuded aorta rings pre-contracted with 10 ~ (-8) mol / L phenylephrine hydrochloride (PE). The aorta rings incubated by 200 mmol / L gastrodin in the Ca ~ (2 +) - free (KH) solution was contracted by using PE. The effect of 200 mmol / L gastrodin on endothelium-denuded aorta rings pre-contracted with 60 mmol / L KCI was also observed. Results: Compared with the denuded gastrodin group, the intact gastrodin group could significantly relax the PE-contracted aorta rings (P <0.01) .In Ca ~ (2 +) - free -induced contraction rate of aorta rings pre-incubated by gastrodin was 6.5% ± 0.7%, whic h was significantly less than the control group (11.8% ± 0.9%, P <0.01). After 3 mmol / L CaCl_2 was added, the Ca ~ (2 +) - induced contraction in the gastrodin group The contractile rate of rings in the KCI-contracted gastrodin group (96.3% ± 0.6%) was not significantly different from that in the control group (96.8% ± 2.8% ± 1.2%). Conclusions: Gastrodin has the effect of vasorelaxation on isolated thoracic aorta rings of rats. The mechanism of the vasorelaxation of gastrodin may mainly work through the inhibition of inositol 1,4,5-trisphosphosphate receptor on the sarcoplasmic reticulum of the arterial smooth muscle, which leads to the reduction of the Ca ~ (2+) released from the sarcoplasmic reticulum.