Bronzetti E, Adani O, Amenta F, Felici L, Mannino F, Ricci A
Dipartimento di Scienze Cardiovascolari e Respiratorie, Università La Sapienza, Rome, Italy.
Neurosci Lett. 1996 Apr 26;208(3):211-5. doi: 10.1016/0304-3940(96)12567-2.
The subtypes of muscarinic cholinergic receptors were studied in human peripheral blood lymphocytes with radioligand binding techniques and the non-selective muscarinic cholinergic receptor antagonist [3H]quinuclidinyl benzylate (QNB) as a ligand. [3H]QNB was bound to human peripheral lymphocytes in a manner consistent with the labelling of muscarinic cholinergic receptors. The dissociation constant (Kd) value was 0.60 +/- 0.08 nM and the maximum density of binding sites (Bmax) was 2.33 +/- 0.03 fmol/2.2 x 10(6) cells. The binding was time-, temperature- and concentration-dependent, belonging to a single class of high affinity sites. Analysis of the pharmacological profile of [3H]QNB binding in the presence of compounds specific for the different muscarinic receptor subtypes suggests that human peripheral blood lymphocytes express mainly muscarinic cholinergic M2 and M3 receptor subtypes and to a lesser extent muscarinic M4 receptors. The characterization of the subtypes of muscarinic cholinergic recognition sites expressed by human peripheral blood lymphocytes may represent a tool for investigating the possible relationships between immune and cholinergic systems in normal and pathologic conditions.
采用放射性配体结合技术，以非选择性毒蕈碱胆碱能受体拮抗剂[3H]喹核醇基苯甲酸酯（QNB）作为配体，对人外周血淋巴细胞中毒蕈碱胆碱能受体的亚型进行了研究。[3H]QNB与人外周淋巴细胞的结合方式与毒蕈碱胆碱能受体的标记一致。解离常数（Kd）值为0.60±0.08 nM，结合位点的最大密度（Bmax）为2.33±0.03 fmol/2.2×10(6)个细胞。这种结合具有时间、温度和浓度依赖性，属于单一类别的高亲和力位点。在存在针对不同毒蕈碱受体亚型的特异性化合物的情况下，对[3H]QNB结合的药理学特征进行分析表明，人外周血淋巴细胞主要表达毒蕈碱胆碱能M2和M3受体亚型，毒蕈碱M4受体的表达程度较低。人外周血淋巴细胞所表达的毒蕈碱胆碱能识别位点亚型的特征描述，可能是一种在正常和病理条件下研究免疫和胆碱能系统之间可能关系的工具。
