Kemp G, Morley B J
FEBS Lett. 1986 Sep 15;205(2):265-8. doi: 10.1016/0014-5793(86)80910-3.
High-affinity (Kd approximately equal to 10 nM) binding sites for nicotine and acetylcholine (ACh) have recently been identified in vertebrate brain. It has been suggested that these sites are desensitized ganglionic (C6) nicotinic acetylcholine receptors (nAChRs). We have tested the pheochromocytoma cell line PC12, which is known to contain well-expressed C6 nAChRs, to determine if these nAChRs are associated with high-affinity [3H]ACh-binding sites. We found that the high-affinity nicotinic [3H]ACh-binding site is absent in PC12 cells. We also found that the concentration of nicotine or ACh necessary to desensitize carbamylcholine-stimulated Na+ flux was at least two orders of magnitude greater than the concentrations used in binding experiments. We conclude that high-affinity nicotinic binding sites are not equivalent to C6 ganglionic receptors.
最近在脊椎动物大脑中发现了对尼古丁和乙酰胆碱（ACh）具有高亲和力（解离常数Kd约等于10 nM）的结合位点。有人提出这些位点是脱敏的神经节（C6）烟碱型乙酰胆碱受体（nAChRs）。我们检测了已知含有高表达C6 nAChRs的嗜铬细胞瘤细胞系PC12，以确定这些nAChRs是否与高亲和力的[3H]ACh结合位点相关。我们发现PC12细胞中不存在高亲和力的烟碱型[3H]ACh结合位点。我们还发现，使氨甲酰胆碱刺激的Na+通量脱敏所需的尼古丁或ACh浓度比结合实验中使用的浓度至少高两个数量级。我们得出结论，高亲和力的烟碱型结合位点与C6神经节受体不等同。
