N-乙酰胆碱受体动力学研究  

Kinetic study of nicotinic acetycholine rceptor

作　　者：张守兰[1] 林福生[1] 余琳 刘敏 

机构地区：[1]防化研究院,北京102205

出　　处：《中国临床药理学与治疗学》1999年第4期286-291,共6页Chinese Journal of Clinical Pharmacology and Therapeutics

摘　　要：目的 开展N-乙酰胆碱受体(N-AChR)的动力学研究.方法 (1)选择a-BuTX作为主要工具药,进行^(125)I-a-BuTX与电鳐电器官的N-AChR饱和结合实验,用Scatfit程序拟合。125I-a-BuTX与电鳐电器官的N-AChR结合的解离动力学实验,当结合达到饱合后,向两个反应体系分别加入1000倍以上的a-BuTX或烟碱.不同时间取样、分离后,γ-计数仪计数。(2) 13日龄的鸡胚骨骼肌N-AChR及20日龄的鸡视叶的N-AChR与^(125)-I-a-BuTX饱和结合实验,用Scaifit程序拟合。另外以烟碱对125I-a-BuTX与电鳐电器官、鸡视叶、鸡胚骨骼肌N-AChR结合的竞争实验,用Logit程序计算IC_(50)值。结果(1)1251-a-BuTX与电鳐电器官的N-AChR饱和结合实验得到一条双曲线的Scatchard图,符合一配基两受体结合模型,求得高、低两个结合位点和两个B_(max)(最大结合值),两个体系的解离动力学均为二次解离曲线,分别求得两个解离常数和两个半衰期.(2)两种实验结果,均符合一配基一受体结合模型,分别求得一个结合位点和一个B_(max).烟碱对^(125)-I-a-BuTX电鳐电器官的N-AChR结合的竞争作用IG_(50)值分别为3.86×10^(-5)和1.65×10^(-6)mol.对鸡视叶的N-AChR竞争作用.IC_(50)值为6.02×10^(-7)mol,对骨骼肌竞争作用IG_(50)值为4.60×10^(-6)。结论 (1)Aim The kinetics of nicotinic acetylcholine receptor (N-AChR) was stadied. MethodsThe saturation experiments of Torpedo electric organ N-AChR were taken with125I-α-BuTX. The results were calculated by Scatfit program. Experiments were thenperformed to study the kinetics of dissociation of α-BuTX and nicotine from N-AChR,respectively. When their binding reached saturation, an excess of 1000 times α-BuTX ornicotine was added. The saturation binding properties of the N-AChR extracted fromleg muscles of the 13th day chick embroys and optic lobes of the 20th day chick em-broys were studied. The results were calculated by Scatfit program. The othe experi-ments were taken to observe the competition between mcotine and 125I-α-BuTX forbinding with Torpedo, optic lobe and skeletal muscle of the chick N-AChRs. ResultsThe saturation experiments of Torpedo electric organ N-AChR resulted in a Scatchardplot of hyperbola which responded to the model of two kinds of receptor with on eli-gand.The difference of and B max between high affinity binding site and low affnitybineing site was significant. The dissaciation experiment showed that the fast dissocia-tion rate of tow ligands was 500 times more than that of the slow dissociation rate. Thisresult suggested that there may be two subtype N-AChRs.The saturation bindingproperties of N-AChR of leg muscles and optic lobe of the chick embroys revealed aScatchard plot of two kinds of N-AChR indicating a single type of site. The bindingaffinity of receptor of optic lobe was 100 times more than that of muscles. In competi-tion for Torpedo receptor by nicotine and 125I-α-BuTX, the values of IC50 were different:which suggested that two kinds of receptor sites were existent. In competition ofNicotine and 125I-α-BuTX for optic lobe and skeletal muscles of the chick N-AChR, thevalue IC50 of skeletal muscles N-AChR was 7. 7 times higher than that of optic lobe. Itindicated that two kinds of N-AChR subtype existed in the optic lobe and in theskeletal muscles of chick respectively. Conclus

关 键 词：动力学 N-乙酰胆碱受体 α-银环蛇毒(α-BuTX) 饱和结合实验 毒蕈碱 

分 类 号：R285.5[医药卫生—中药学] R282.740.5[医药卫生—中医学]