Lees G, Beadle D J, Botham R P
Brain Res. 1983 Dec 12;288(1-2):49-59. doi: 10.1016/0006-8993(83)90080-x.
Cultured neurones from the cockroach, Periplaneta americana, have been used to investigate putative acetylcholine receptors. Ligand-binding experiments revealed that these neurones possessed an alpha-bungarotoxin binding site that was saturable, had an apparent affinity constant of 3.51 nM and was predominantly nicotinic in nature. An individual culture of 50,000 neurones had a maximum of 4200 pmol. binding sites per gram of protein. [I125]alpha-BTX autoradiography showed the binding sites to be distributed over both the neuronal cell bodies and their associated axonal processes. Both acetylcholine and nicotine applied by pressure ejection to the neuronal soma induced depolarizing responses and in the majority of cells tested the response was blocked by alpha-BTX at a concentration of 25 nM in a time dependent manner. Some of the neurones, however, were depolarized by acetylcholine and nicotine after 3 h incubation in alpha-BTX. These experiments suggest that two populations of cells possessing extrajunctional nicotinic receptors were present in these cultures. In the majority of cells these receptors were sensitive to alpha-BTX but in a subpopulation the receptors were unaffected by this toxin.
来自美洲大蠊的培养神经元已被用于研究假定的乙酰胆碱受体。配体结合实验表明，这些神经元具有一个可饱和的α-银环蛇毒素结合位点，其表观亲和常数为3.51 nM，且本质上主要是烟碱型的。每50,000个神经元的单个培养物中，每克蛋白质最多有4200 pmol的结合位点。[I125]α-BTX放射自显影显示结合位点分布在神经元细胞体及其相关的轴突上。通过压力喷射施加到神经元胞体的乙酰胆碱和尼古丁均诱导去极化反应，并且在大多数测试细胞中，25 nM浓度的α-BTX以时间依赖性方式阻断了该反应。然而，在α-BTX中孵育3小时后，一些神经元被乙酰胆碱和尼古丁去极化。这些实验表明，这些培养物中存在两类具有接头外烟碱受体的细胞群体。在大多数细胞中，这些受体对α-BTX敏感，但在一个亚群中，受体不受该毒素的影响。
