中文摘要：

目的：研究罗布麻叶提取物（extracts from leaves of Apocynum venetum,ELA）对离体大鼠胸主动脉环的作用及其可能的机制。方法：采用累积加药法,观察ELA对苯肾上腺素（PE）预收缩的主动脉环张力的影响;观察hemoglobin,亚甲蓝（MB）预处理对ELA扩血管作用影响;观察左旋硝基精氨酸甲酯盐酸盐（L-NAME）,甲基异硫脲硫酸盐（SMT）预处理对ELA的扩血管作用的影响;观察四乙胺（TEA）,4-氨基吡啶（4-AP）和格列苯脲（GLB）对ELA的血管舒张作用的影响;采用Ca2＋剥夺和复加法,观察ELA对细胞内钙释放和外钙内流所引起的血管环收缩反应的作用。结果：ELA可显著舒张PE预收缩的主动脉环,低浓度下（1×10-6～3×10-4）g.mL-1为内皮依赖性作用,而高浓度下（3×10-4,1×10-3）g.mL-1则为内皮非依赖性舒张。低浓度下（1×10-6～3×10-4）g.mL-1,ELA的扩血管作用可被Hemoglobin,MB（P〈0.05）和L-NAME,SMT（P〈0.05）阻断。高浓度下（3×10-4～3×10-3）g.mL-1,ELA可显著抑制细胞内钙释放和细胞外钙内流（P〈0.05）;钾通道阻滞剂TEA,4-AP和格列苯脲可不同程度地阻断ELA扩血管作用。结论：ELA可剂量依赖性的舒张PE预收缩的胸主动脉环,呈现低浓度下内皮依赖、高浓度下内皮非依赖的特点。低浓度下ELA的血管舒张作用可能与NO释放有关,高浓度下其作用需要Ca2＋,K＋通道参与。

英文摘要：

Objective： To investigate the vascular effects of extracts from leaves of Apocynum venetum（ELA） and its mechanisms.Method： Phenylephrine（PE） was used to contract isolated rat thoracic aorta.Concentration relaxation curve of ELA（1× 10-6-3×10-3 g·mL-1） was constructed in cumulative doses manner.Moreover,vasodilator effects of ELA were re-determined after pre-incubated with several antagonists.Result： ELA showed significant vasodilator properties.At low concentration,vascular effects of ELA were inhibited by hemoglobin,methylene blue（MB）,NG-nitro-L-arginine methyl ester（L-NAME） and S-methylisothiourea sulfata（SMT）.At high concentration,Ca2＋-induced contraction was suppressed by ELA.In addition,the K＋ channel blocking agents tetraethylammonium（TEA）,4-aminopyridine（4-AP） and glibenclamide（GLB） inhibited the vasodilator responses of ELA.Conclusion： ELA showed vasodilator effects with property of endothelium-dependency at low concentration and endothelium-independency at high concentration.At low concentration,the vasodilator response of ELA was related to the release of NO,but at high concentration,this action may be associated with Ca2＋ and K＋.