Buckley N, Burnstock G
Brain Res. 1984 Feb 27;294(1):15-22. doi: 10.1016/0006-8993(84)91305-2.
Muscarinic receptors mediate a variety of intestinal functions including smooth muscle contraction, ganglionic transmission and water and electrolyte secretion. In this study, we have used [3H]quinuclidinyl benzilate ([3H]QNB) in an in vitro autoradiographic method to map the distribution of muscarinic receptors in guinea-pig ileum, colon and caecum. In addition, the relative distribution of low and high affinity agonist binding sites was assessed by the addition of the muscarinic agonist, carbachol, to selectively inhibit the binding of [3H]QNB to the high affinity sites. Although quantitative differences existed, the overall distribution of muscarinic receptors was similar in the 3 regions of intestine examined. Autoradiograph grains were found distributed over the myenteric and sub-mucous plexuses, the longitudinal and circular muscle layers and in the case of the colon, the muscularis mucosa. The inclusion of carbachol demonstrated that a greater proportion of high affinity sites were associated with the musculature than with the enteric plexuses. These findings are discussed in relation to the role of muscarinic mechanisms in intestinal motility and secretion.
毒蕈碱受体介导多种肠道功能，包括平滑肌收缩、神经节传递以及水和电解质分泌。在本研究中，我们采用[3H]喹核醇基苯甲酸酯（[3H]QNB）体外放射自显影法来绘制豚鼠回肠、结肠和盲肠中毒蕈碱受体的分布图。此外，通过添加毒蕈碱激动剂卡巴胆碱来选择性抑制[3H]QNB与高亲和力位点的结合，从而评估低亲和力和高亲和力激动剂结合位点的相对分布。尽管存在数量差异，但在所检查的肠道3个区域中毒蕈碱受体的总体分布相似。放射自显影片上的颗粒分布于肌间神经丛和黏膜下神经丛、纵行肌层和环行肌层，在结肠中还分布于黏膜肌层。加入卡巴胆碱表明，与肠道神经丛相比，高亲和力位点在肌肉组织中的比例更大。结合毒蕈碱机制在肠道运动和分泌中的作用对这些发现进行了讨论。
