Site selectivity of competitive antagonists for the mouse adult muscle nicotinic acetylcholine receptor.
Site selectivity of competitive antagonists for the mouse adult muscle nicotinic acetylcholine receptor.
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DOI：
10.1124/mol.108.051060
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发表时间：
2009-01
影响因子：
3.6
通讯作者：
Dilger JP
中科院分区：
文献类型：
--
作者：
Liu M;Dilger JP
肌肉型烟碱乙酰胆碱受体具有两个不同的配体结合位点。乙酰胆碱和竞争性拮抗剂（+）-筒箭毒碱和甲箭毒碱对成年小鼠受体的选择性是已知的。在这里，我们研究了其他四种竞争性拮抗剂的位点选择性：顺库溴铵，潘库溴铵，维库溴铵和罗库溴铵。我们迅速将乙酰胆碱应用于转染的BOSC 23细胞的外向贴片，并测量宏观电流。之前，我们单独报道了拮抗剂的IC 50。在这里，我们确定抑制对竞争性拮抗剂。至少有一种拮抗剂的浓度可产生≥67%的受体抑制。甲箭毒碱改变了（+）-筒箭毒碱的表观IC 50，与完全竞争性拮抗作用定量一致。与维库溴铵竞争的泮库溴铵也观察到同样的结果。然而，pancuronium和vecuronium每个移动（+）-筒箭毒碱的表观IC 50小于预期的完全竞争，但大于预期的独立结合。顺利库铵和（+）-筒箭毒碱或甲箭毒碱的情况相似。顺式利库铵没有改变潘库溴铵或维库溴铵的表观IC 50，表明这两对的独立结合。将数据拟合至双位点双拮抗剂模型，以确定每个位点的拮抗剂结合常数Lαε和Lαδ。顺库溴铵、泮库溴铵、维库溴铵和罗库溴铵的Lαε/Lαδ分别为0.22（0.14-0.34）、20（9-29）、21（4-36）和1.5（0.3-2.9）。某些拮抗剂的Lαε/Lαδ范围较宽，可能反映了低亲和力位点的实验不确定性、相对较差的选择性（罗库），或可能表明拮抗剂在一个位点的结合影响第二个位点的亲和力。
The muscle-type nicotinic acetylcholine receptor has two non-identical binding sites for ligands. The selectivity of acetylcholine and the competitive antagonists (+)-tubocurarine and metocurine for adult mouse receptors is known. Here, we examine the site-selectivity for four other competitive antagonists: cisatracurium, pancuronium, vecuronium and rocuronium. We rapidly applied acetylcholine to outside-out patches from transfected BOSC23 cells and measured macroscopic currents. Previously, we reported the IC50 of the antagonists individually. Here, we determined inhibition by pairs of competitive antagonists. At least one antagonist was present at a concentration producing ≥67% receptor inhibition. Metocurine shifted the apparent IC50 of (+)-tubocurarine in quantitative agreement with complete competitive antagonism. The same was observed for pancuronium competing with vecuronium. However, pancuronium and vecuronium each shifted the apparent IC50 of (+)-tubocurarine less than expected for complete competition but more than expected for independent binding. The situation was similar for cisatracurium and (+)-tubocurarine or metocurine. Cisatracurium did not shift the apparent IC50 of pancuronium or vecuronium, indicating independent binding of these two pairs. The data were fit to a two-site, two-antagonist model to determine the antagonist binding constants for each site, Lαε and Lαδ. We found Lαε/Lαδ = 0.22 (range 0.14-0.34), 20 (9-29), 21 (4-36) and 1.5 (0.3-2.9) for cisatracurium, pancuronium, vecuronium and rocuronium respectively. The wide range of Lαε/Lαδ for some antagonists may reflect experimental uncertainties in the low affinity site, relatively poor selectivity (rocuronium) or may indicate that the binding of an antagonist at one site affects the affinity of the second site.
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影响因子：
64.8
作者：
HAMILL, OP;SAKMANN, B
通讯作者：
SAKMANN, B
影响因子：
5.6
作者：
Unwin, N
通讯作者：
Unwin, N
影响因子：
3.4
作者：
LIU, Y;DILGER, JP
通讯作者：
DILGER, JP
影响因子：
16.2
作者：
Ohno, K;Wang, HL;Engel, AG
通讯作者：
Engel, AG
DOI：
10.1039/jr9350001381
发表时间：
1935-01-01
期刊：
JOURNAL OF THE CHEMICAL SOCIETY
影响因子：
--
作者：
King, H
通讯作者：
King, H