Muzio F, Malandrino S, Ferrari M, Tonon G
Life Sci. 1986 Jul 28;39(4):365-71. doi: 10.1016/0024-3205(86)90655-7.
The high-affinity muscarinic antagonist /3H/-Quinuclidinyl benzilate (/3H/-QNB) has been used to label muscarinic receptors in a crude membrane fraction of rat cerebral cortex, colon and heart. The inhibition of /3H/-QNB binding by Atropine, Oxotremorine and Pirenzepine was investigated at three temperatures: 37 degrees C, 22 degrees C and 10 degrees C. The IC50 values and the proportion of high (Rt1) and low (Rt2) affinity binding sites were determined for the three compounds. When the temperature were lowered from 37 degrees C to 10 degrees C, in the agonist and antagonist dissociation constants decreased in all tissues. Changes in temperature did not modify Rt1 or Rt2 values for Oxotremorine and Pirenzepine. The results show marked temperature-dependent modifications of IC50 values for muscarinic receptors of high- and low-affinity sites in rat cerebral cortex, colon or heart.
高亲和力毒蕈碱拮抗剂/³H/-奎宁环基苯甲酸酯（/³H/-QNB）已被用于标记大鼠大脑皮层、结肠和心脏粗膜部分中的毒蕈碱受体。在三个温度下研究了阿托品、氧震颤素和哌仑西平对/³H/-QNB结合的抑制作用：37℃、22℃和10℃。测定了这三种化合物的半数抑制浓度（IC50）值以及高亲和力（Rt1）和低亲和力（Rt2）结合位点的比例。当温度从37℃降至10℃时，所有组织中激动剂和拮抗剂的解离常数均降低。温度变化未改变氧震颤素和哌仑西平的Rt1或Rt2值。结果表明，大鼠大脑皮层、结肠或心脏中高亲和力和低亲和力位点的毒蕈碱受体的IC50值存在明显的温度依赖性变化。
