Studies on the electrogenic action of acetylcholine with Torpedo marmorata electric organ. II. The permeability response of the receptor-rich membrane fragments to cholinergic agonists in vitro.
Studies on the electrogenic action of acetylcholine with Torpedo marmorata electric organ. II. The permeability response of the receptor-rich membrane fragments to cholinergic agonists in vitro.
复制标题
鱼雷鱼雷电器官乙酰胆碱生电作用的研究。
DOI：
10.1016/0022-2836(76)90247-3
复制
发表时间：
1976
影响因子：
5.6
通讯作者：
J. Changeux
中科院分区：
文献类型：
--
作者：
J. Popot;H. Sugiyama;J. Changeux
纯化的富含受体的膜片段（spec. act. 1000 ± 400 nmol ~ 3 H标记的α毒素位点/g蛋白质）形成封闭的囊泡，将~（22）Na ~+保留在游离区和膜结合区。乙酰胆碱（用0.01 mm-Tetram †阻断乙酰胆碱酯酶后）、氨甲酰胆碱、苯基三甲铵、辛二酰胆碱和甲基二异丙基苯促进游离22 Na+从这些微囊的释放，氨甲酰胆碱的作用被Naja nigricollisα-毒素、d-筒箭毒碱、flaxedil和hexamethonium阻断。Decamethonium，一种T激动剂。marmorataelectroplaque，作为一个竞争性拮抗剂，在这个体外系统。两种局麻药二甲异喹和SKF-525 A在体外阻断了这种反应。的常数的值是，对于他们中的大多数人，显着大于那些measuredin vivowith电蚀斑以下的稳态去极化中存在的激动剂添加在浴（另一方面，他们相吻合，而与直接结合的研究与胆酸盐增溶受体的平衡解离常数）。用膜结合受体测定的真实的解离常数与所有拮抗剂的表观解离常数接近。然而，激动剂的结合浓度比触发反应所需的浓度小两个数量级。
Purified receptor-rich membrane fragments (spec. act. 1000 ± 400 nmol3H-labelled α-toxin sites/g protein) fromTorpedo marmoratamake closed vesicles which retain22Na+in free and membrane-bound compartments. Acetylcholine (after blocking acetylcholinesterase with 0.01 mm-Tetram†), carbamylcholine, phenyltrimethylammonium, suberyldicholine and methyldilvasene enhance the release of the free22Na+from these microsacs and the effect of carbamylcholine is blocked byNaja nigricollisα-toxin, d-tubocurarine, flaxedil and hexamethonium. Decamethonium, an agonist onT. marmorataelectroplaque, acts as a competitive antagonist on thisin vitrosystem. Two local anaesthetics, dimethisoquin and SKF-525A block the responsein vitro.Apparentdissociation constants for cholinergic ligands are determined from the dose-response curves. The values of the constants are, for most of them, significantly larger than those measuredin vivowith the electroplaque by following steady-state depolarization in the presence of agonist added in the bath (on the other hand, they coincide rather well with the equilibrium dissociation constants given by direct binding studies with the cholate-solubilized receptor). The real dissociation constants measured with the membrane-bound receptor are close to the apparent ones for all theantagoniststested. However, theagonistsbind at concentrations two orders of magnitude smaller than those necessary to trigger the response.