Wang H, Cui W Y, Liu C H
Institute of Pharmacology and Toxicology, Beijing, China.
Zhongguo Yao Li Xue Bao. 1996 Nov;17(6):497-9.
To study the modulatory effects of nicotine on the binding of brain muscarinic receptors.
The binding of brain muscarinic receptors with the agonist [3H] oxotremorine-M or the antagonist l-[3H]QNB was determined in the presence/absence of nicotine.
Pre-incubation of the membrane fraction derived from rat cerebral cortex with nicotine 1.0 mumol.L-1 led to a decrease in the dissociation constant (Kd) for [3H] oxotremorine-M binding to muscarinic receptors, while the maximal binding value (Bmax) was unchanged. The Kd value for binding of the muscarinic antagonist l-[3H]QNB was concentration-dependently increased by preincubation with nicotine 0.1 nmol.L-1-10.0 mumol.L-1, with Bmax unchanged. The effect of nicotine on the Kd for l-[3H]QNB binding was prevented by mecamylamine 10 nmol.L-1, but was enhanced by dithiothreitol 10 mumol.L-1, which by itself was also capable of increasing the Kd value.
Nicotine increases the affinity of brain muscarinic receptors for muscarinic agonist, but decreases the affinity of brain muscarinic receptors for muscarinic antagonist.
研究尼古丁对脑毒蕈碱受体结合的调节作用。
在有/无尼古丁存在的情况下，测定脑毒蕈碱受体与激动剂[3H]氧化震颤素-M或拮抗剂l-[3H]QNB的结合。
用1.0μmol.L-1尼古丁预孵育大鼠大脑皮质膜组分，导致[3H]氧化震颤素-M与毒蕈碱受体结合的解离常数（Kd）降低，而最大结合值（Bmax）不变。用0.1nmol.L-1-10.0μmol.L-1尼古丁预孵育，毒蕈碱拮抗剂l-[3H]QNB结合的Kd值呈浓度依赖性增加，Bmax不变。10nmol.L-1美加明可阻止尼古丁对l-[3H]QNB结合Kd的影响，但10μmol.L-1二硫苏糖醇可增强该影响，二硫苏糖醇本身也能增加Kd值。
尼古丁增加脑毒蕈碱受体对毒蕈碱激动剂的亲和力，但降低脑毒蕈碱受体对毒蕈碱拮抗剂的亲和力。
