Maslinski W, Kullberg M, Nordström O, Bartfai T
Department of Pathophysiology, Institute of Rheumatology, Warsaw, Poland.
J Neuroimmunol. 1988 Mar;17(4):265-74. doi: 10.1016/0165-5728(88)90118-x.
Rat thymocytes possess a single class of saturable, high affinity binding sites for muscarinic antagonists of the benzilate type such as [3H]3-quinuclidinyl benzilate ([3H]3-QNB). The average number of receptors per cell is 3000 and the equilibrium dissociation constant of [3H]3-QNB on intact cells is 7.5 nM. In the work reported here we found that perturbation of the thymocyte membrane by addition of phytohemagglutinin (4 micrograms/ml) caused a transient increase in muscarinic antagonist binding, and hydrocortisone (100 mg/kg s.c.) treatment of rats for 2 days prior to sacrifice increased the average number of muscarinic receptor sites on thymocytes by 100%. Atropine treatment, which in other tissues causes increased muscarinic receptor concentration, did not alter the receptor number on thymocytes. Binding of carbachol to the receptor on intact cells resulted in inhibition of cAMP synthesis and stimulation of cGMP synthesis. These muscarinic agonist effects were each inhibited by the simultaneous addition of the muscarinic antagonist atropine (5 X 10(-5) M). No stimulation of phosphatidylinositol turnover by muscarinic agonists was observed.
大鼠胸腺细胞具有一类对诸如[3H]3-喹核醇基苯甲酸酯（[3H]3-QNB）这类苯甲酸酯型毒蕈碱拮抗剂的可饱和、高亲和力结合位点。每个细胞的受体平均数量为3000个，[3H]3-QNB在完整细胞上的平衡解离常数为7.5 nM。在本文报道的研究中，我们发现添加植物血凝素（4微克/毫升）对胸腺细胞膜的扰动导致毒蕈碱拮抗剂结合的短暂增加，并且在处死大鼠前2天对其进行皮下注射氢化可的松（100毫克/千克）处理使胸腺细胞上毒蕈碱受体位点的平均数量增加了100%。在其他组织中会导致毒蕈碱受体浓度增加的阿托品处理，并未改变胸腺细胞上的受体数量。卡巴胆碱与完整细胞上的受体结合导致环磷酸腺苷（cAMP）合成的抑制和环磷酸鸟苷（cGMP）合成的刺激。毒蕈碱拮抗剂阿托品（5×10⁻⁵ M）的同时添加分别抑制了这些毒蕈碱激动剂的作用。未观察到毒蕈碱激动剂对磷脂酰肌醇周转率的刺激作用。
