Ahmad S, Daniel E E
Department of Biomedical Sciences, McMaster University Health Science Centre, Hamilton, Ontario, Canada.
Peptides. 1991 May-Jun;12(3):623-9. doi: 10.1016/0196-9781(91)90111-2.
We have previously characterized the neurotensin receptors on the circular smooth muscle (CM) of the canine small intestine (1). In the present studies, using radioligand binding technique, neurotensin receptors were localized on the membranes from deep muscular (DMP) and the submucous plexus while no binding was observed on either the longitudinal smooth muscle or myenteric plexus membranes. The high affinity binding sites (Kd 0.1-0.2 nM) on DMP membranes were similar to those on CM; the low affinity component was of much lower affinity (Kd approximately 40 nM). DMP had 4-6 times higher density of binding sites than the CM. The recognition properties of DMP receptors were similar to those on the CM and reduced sulfhydryl groups were required for the binding activity. The action of neurotensin on the contractility of the canine small intestine, therefore, appears to be through a direct action on the circular smooth muscle and through the prejunctional action on the DMP neurons through distinct receptors. Thiol groups in the neurotensin receptors may be important for the receptor function.
我们之前已对犬小肠环形平滑肌（CM）上的神经降压素受体进行了表征（1）。在本研究中，使用放射性配体结合技术，神经降压素受体定位于深肌层（DMP）和黏膜下神经丛的膜上，而在纵行平滑肌或肌间神经丛膜上未观察到结合。DMP膜上的高亲和力结合位点（Kd 0.1 - 0.2 nM）与CM上的相似；低亲和力成分的亲和力则低得多（Kd约为40 nM）。DMP的结合位点密度比CM高4至6倍。DMP受体的识别特性与CM上的相似，且结合活性需要还原的巯基。因此，神经降压素对犬小肠收缩性的作用似乎是通过对环形平滑肌的直接作用以及通过不同受体对DMP神经元的节前作用来实现的。神经降压素受体中的巯基可能对受体功能很重要。
