天麻素对离体大鼠胸主动脉环的舒张作用及其机制

目的:研究天麻素对离体大鼠胸主动脉环的舒张作用并探讨其可能的机制。方法:记录去甲肾上腺素(NE)和KCl预收缩的离体大鼠主动脉环张力变化,观察天麻素的舒血管作用及不同工具药对其作用的影响。结果:天麻素对去甲肾上腺素(NE,1×10-6mol.L-1)和KCl(6×10-2mol.L-1)引起的去内皮和内皮完整胸主动脉环的收缩均有舒张作用,二者没有显著差别;L-硝基精氨酸甲酯(L-NAME,1×10-4mol.L-1)、亚甲蓝(MB,1×10-5mol.L-1)、吲哚美辛(INDO,1×10-5mol.L-1)并不能抑制天麻素对胸主动脉环的舒张作用;钾离子通道阻断剂4-氨基吡啶(4-AP,1×10-4mol.L-1)、四乙基胺(TEA,1×10-3 mol.L-1)、格列苯脲(glibenclamide,1×10-5mol.L-1)、BaCl2(1×10-4mol.L-1)均能抑制天麻素对血管环的舒张作用;在无钙环境下,预孵育天麻素对去甲肾上腺素收缩有明显抑制作用。结论:天麻素有浓度依赖性的血管舒张作用,此作用不依赖血管内皮,与钾离子通道及抑制血管平滑肌细胞内质网储存钙的释放和外钙内流有关系。

Effect and mechanism of gastrodin in relaxing isolated thoracic aorta rings in rats

Objective: To investigate the effect of gastrodin in relaxing isolated thoracic aorta rings in rats and discuss its possible mechanism. Method: Isotonic tension of isolated thoracic aortic rings in rats with norepineprine (NE) and KCl was recorded to observe the vasodilatory effect of gastrodin and the influence of various drugs on it. Result: Gastrodin had the effect in relaxing thoracic aortas with or without endothelium, and there was no significant difference. NG-nitro-L-argininemethylester (L-NAME, 1×10^-4 mol·L^-1), methylene blue (MB, 1×10^-5 mol·L^-1), indomethacin (INDO, 1×10^-5 mol·L^-1) had no effect on the vasodilation action of gastrodin on thoracic aortas precontracted by NE. 4-aminopyrimide (4-AP, 1×10^-4 mol·L^-1), tetrathylamonium (TEA, 1×10^-3 mol·L^-1), BaCl₂ (1×10^-4 mol·L^-1) and glibenclamide (Gli, 1×10^-5 mol·L^-1) could inhibit gastrodin's effect in relaxing thoracic aorta rings. In the absence of Ca²⁺, pre-incubated gastrodin showed a notable inhibitory effect in relaxing NE contraction. Conclusion: Gastrodin shows a dose-dependent and endothelium-independent effect in relaxing rat isolated thoracic aorta rings. The mechanism is related to K⁺ channel, inhibition of release of Ca²⁺ stored in endoplasmic reticulum of vascular smooth muscle cells and inflow of external calcium Ca²⁺.