【摘要】 杀虫植物苦皮藤Celastrus angulatus的主要活性成分苦皮藤素Ⅳ和Ⅴ处理后昆虫的中毒症状分别表现为麻醉和兴奋,但苦皮藤素Ⅳ对苦皮藤素Ⅴ的毒杀效果具有增效作用,苦皮藤素Ⅴ对苦皮藤素Ⅳ的麻醉作用基本没有影响。应用全细胞膜片钳技术,就苦皮藤素Ⅳ和Ⅴ不同比例(3∶1,1∶1,1∶3)混合物对棉铃虫Helicoverpa armigera幼虫离体培养神经细胞钠离子通道的影响进行了比较。结果表明:苦皮藤素Ⅳ和苦皮藤素Ⅴ的不同比例混合物对钠通道(TTX-S)电流作用与二者所占比例有关,苦皮藤素Ⅳ比例大,表现出苦皮藤素Ⅳ对通道的阻滞效应,钠电流被抑制;苦皮藤素Ⅴ比例大,则表现出对通道的激活,钠电流增大。另外,两者不同比例混合物对钠通道(TTX-S)电流的激活电压无明显影响,但对峰值电压影响显著,可使其向正电位方向移动10~20mV。这些结果说明苦皮藤素Ⅳ和Ⅴ可能作用于一个相同的钠通道结合位点或别构偶联位点,二者对钠通道的作用是一种拮抗作用。更多还原

【Abstract】 Celangulin Ⅳ and Ⅴ from the root bark of Celastrus angulatus are the major active ingredients of the insecticidal plant which can result in reverse nerve poisoning symptoms, i.e., narcosis and excitation, respectively. The insecticidal efficacy of celangulin Ⅴ can be synergied by celangulin Ⅳ, but celangulin Ⅴ has no synergistic effects on the narcotic efficacy of celangulin Ⅳ. By using patch-clamp technique, the interaction of celangulin Ⅳ and Ⅴin different ratio (3∶1, 1∶1, 1∶3) mixtures on tetrodotosin (TTX)-sensitive inward sodium channel current (I_ Na ) in cultured nerve cell of cotton bollworm (Helicoverpa armigera) was investigated. The results showed that the effects corresponded with the ratio of celangulin Ⅳ and Ⅴ in a mixture. When the ratio of celangulin Ⅳ in a mixture was high, voltage gated sodium channel (VGSC) was blocked and TTX-sensitive I_ Na was decreased. When the ratio of celangulin Ⅴ in a mixture was high, VGSC was activated and TTX-sensitive I_ Na was increased. Different ratio mixtures of celangulin Ⅳ and Ⅴ showed no effect on activated voltage, except the peak voltage shifted to positive potential 10-20 mV. The results suggest that celangulin Ⅳ and Ⅴ share a binding site of VGSC or they bind to separate sodium channel sites which interact altosterically with each other, and they might antagonistically compete each other to bind the site on VGSC.更多还原