黄芪舒张血管平滑肌的作用及机制

Relaxant effect of Astragalus membranaceus on smooth muscle cells of rat thoracic aorta

目的 :探讨黄芪对血管平滑肌的舒张作用及其机制。方法 :采用大鼠离体胸主动脉环灌流模型。在去除血管环内皮后 ,观察累积浓度黄芪对基础状态 (基础组 )、苯肾上腺素 (PE)预收缩 (苯肾上腺素组 )、氯化钾预收缩(氯化钾组 )的血管环的作用和黄芪对经无钙液 (无钙液组 )、无钙液加肝素 (肝素组 )、普萘洛尔 (普萘洛尔组 )预处理后的血管环的作用。结果 :在血管内皮被去除后 ,黄芪对基础状态或氯化钾预收缩的血管环无影响 ;当黄芪浓度累积达 (10 -1、3× 10 -1、10 0 、3× 10 0 ) g/L时 ,对 PE(3× 10 -7mol/L)预收缩的血管环产生剂量依赖性舒张作用 (P<0 .0 5 )。经无钙液预处理后 ,黄芪 (3× 10 0 g/L )对血管环的舒张作用未被阻断 ;但经无钙液加肝素预处理后 ,该作用被显著抑制 (P<0 .0 1) ;而普萘洛尔预处理不影响黄芪对 PE预收缩血管环的舒张作用。结论 :黄芪对去除内皮的血管具有舒张作用。其机制可能与阻断血管平滑肌细胞内质网上的三磷酸肌醇敏感的钙离子通道 ,抑制内钙的释放有关。

Objective: To investigate the effect of Astragalus membranaceus (AM) on vascular circles and the underlying mechanisms. Methods: The study was performed with the model of isolate rat thoracic aorta rings in organ bath.When the endothelium of rat thoracic aorta was removed,the effect of accumulated AM on aorta rings in resting tension,or pre constricted with KCl,or pre constricted with phenylephrine (PE) was observed. And to explove the mechanism, the aorta rings were incubated with Ca 2+ free medium alone,or Ca 2+ free medium plus heparin , or propranolol alone before pre contraction with PE. Results: AM had no significant effects on aorta rings in resting tension or pre constricted with KCl.When the concentration of AM was cumulated to 10 -1 ,3×10 -1 ,10 0,3×10 0 g/L,it caused concentration dependent relaxation while aorta rings were pre constricted with PE(3×10 -7 mol/L),compared with the control[(90 4±4 2)% vs (94 7±2 4)%,(86 1±5 0)% vs (92 6±3 2)%,(82 3±5 9)% vs (90 4±3 6)%,(78 3±6 0)% vs (88 1±4 0)%]. This effect was not inhibited by Ca 2+ free medium or propranolol alone. However,the effect was attenuated by the co incubation with heparin and Ca 2+ free medium [without heparin:(76 2±4 3)% vs (92 3±5 9)%,with heparin:(95 3±0 5)% vs (95 1±0 6)%]. Conclusion: The results indicate that AM can relax the rat thoracic aorta rings without endothelium.The mechanism may include the inhibition of intracellular calcium ions release by the 1,4,5 triphosphate inositol receptor dependent pathway in vascular smooth muscle cells.