蜂胶乙醇提取物(EEP)对豚鼠胸主动脉的舒张作用

Vasorelaxation Effects of Ethanol Extracts of Propolis(EEP) on Guinea Pig Thoracic Aorta

目的:探讨蜂胶水提物(WEP)和乙醇提物(EEP)的血管舒张作用。方法:以离体豚鼠胸主动脉环为材料,采用离体实验方法记录血管收缩张力。结果:对于PE(PE,1μM)和KC1(60mM)预收缩的主动脉环,EEP可以剂量依赖地使其舒张。去除内皮后舒张作用减弱,所以这种作用是内皮依赖性的;使用NO合酶抑制剂N-硝基-L-精氨酸(L-NNA,10μM)、鸟苷酸环化酶抑制剂(methylene blue,10μM)或者前列腺素合成酶抑制剂(indomethacin,10μM)预处理,血管舒张作用也减弱。这提示EEP的作用可能与血管内皮释放的一氧化氮和前列腺素有关;K^+通道通用抑制剂TEA(tetraethylammonium chloride,1 mM)的处理对EEP的舒血管作用没有影响,显示EEP对豚鼠动脉环的舒张作用与K^+通道无关;另外,EEP能使CaCl_2的量效曲线下移,说明EEP可以抑制细胞外Ca^(2+)的内流,同时EEP还可以抑制细胞内Ca^(2+)的释放。结论:蜂胶乙醇提取物EEP能剂量依赖地引起离体豚鼠动脉环舒张。这种舒张作用与K^+通道无关,但受内皮NO-鸟苷酸环化酶途径和前列腺素调控,最终通过降低细胞内Ca^(2+)的浓度舒张血管。

Objective： To investigate the vasorelaxant effect of water extract of propolis （WEP） and ethanol extract of propolis （EEP） on guinea pig thoracic aorta. Methods： In this experiment,guinea pig thoracic aortic rings in vitro were selected, and vasoconstriction tension was recorded by using a strain gauge transducer. Results： EEP （1-100mg/L） had concentration-dependent relaxant effects to KCl （60 mM） and phenylephrine （PE, 1μM） induced contractions, and these effects were endothelium-depended, because in endothelium-removed vessels the effects of EEP were weakened. When pretreated with a nitric oxide synthase inhibitor N-nitro-L-arginine （L-NNA, 10μM）, guanylyl cyclase inhibitor methylene blue （MB, 10μM）, or cyclo-oxygenase inhibitor indomethacin （10 μM） the responses to EEP were attenuated. This indicated the relaxant effects of EEP could involve the release of nitric oxide and prostaglandins from the endothelium. However, when incubations with calcium-activated potassium channel blocker tetraethylammonium chloride （TEA, 1mM ） the response induced by EEP did not modify, indicating the impossible involvement of calcium-activated potassium channels. At high concentration, the relaxant action of the EEP included inhibition of Ca^2＋ influx and release of Ca^2＋ from intracellular stores. Because, when the aortic rings were treated with EEP （ 100mg/ L）, the CaCl2-induced contractions were attenuated. In addition, EEP could inhibit the contraction of thoracic aortic rings induced by KCl or PE. However, our result showed that the water extract of propolis had no effect. Conclusion： Eethanol extract of propolis （EEP） showed concentration-depended vasorelaxation effects, the effects were mediated by NO guanylyl cyclase pathway and the release of prostaglandins from the endothelium, not related to calcium-activated potassium channels. Ultimately, the effect of EEP worked through reducing the concentration of Ca^2＋.