Keast J R, Furness J B, Costa M
Naunyn Schmiedebergs Arch Pharmacol. 1986 Aug;333(4):393-9. doi: 10.1007/BF00500015.
Noradrenaline (NA) and somatostatin (SOM) stimulate intestinal water and ion absorption and are found in mucosal nerve fibres and nerve terminals in submucous ganglia of the guinea-pig small intestine. As the main projection of submucous neurons is to the mucosa, NA and SOM might alter mucosal transport either by a direct effect on the epithelium or indirectly, by affecting submucous neurons. In this study these two possible sites of action of NA and SOM have been investigated in mucosa-submucosa preparations of guinea-pig ileum. In addition, the actions of NA and SOM on the secretory responses caused by stimulation of different populations of submucous neurons have been studied. The stimulants of secretion used were a nicotinic agonist, 1,1-dimethyl-4-phenylpiperazinium (DMPP, 10(-5) M), 5-hydroxytryptamine (5-HT, 10(-7) M) and electrical field stimulation (EFS), which activate cholinergic, noncholinergic and mixed populations of submucous secretomotor neurons, respectively. Segments of intestine were dissected free of external muscle and myenteric plexus and mounted in Ussing chambers. Short-circuit current (Isc) was measured as an indication of net active ion transport across the tissue. NA (greater than or equal to 10(-8) M) and SOM (greater than 10(-10) M) each caused a decrease in Isc, indicating a net increase in ion absorption. The NA response was abolished and the magnitude of the SOM response was reduced to 20% by tetrodotoxin (10(-7) M). DMPP, 5-HT and EFS each stimulated nerves that increased Isc and each of these responses was significantly diminished by NA and SOM.(ABSTRACT TRUNCATED AT 250 WORDS)
去甲肾上腺素（NA）和生长抑素（SOM）可刺激肠道对水和离子的吸收，且存在于豚鼠小肠黏膜下神经节的黏膜神经纤维和神经末梢中。由于黏膜下神经元的主要投射部位是黏膜，NA和SOM可能通过直接作用于上皮细胞或通过影响黏膜下神经元间接改变黏膜转运。在本研究中，已在豚鼠回肠的黏膜-黏膜下层制备物中研究了NA和SOM这两种可能的作用位点。此外，还研究了NA和SOM对不同群体的黏膜下神经元受刺激引起的分泌反应的作用。所使用的分泌刺激剂为烟碱激动剂1,1-二甲基-4-苯基哌嗪鎓（DMPP，10⁻⁵ M）、5-羟色胺（5-HT，10⁻⁷ M）和电场刺激（EFS），它们分别激活胆碱能、非胆碱能和混合群体的黏膜下分泌运动神经元。将肠段剥离外部肌肉和肌间神经丛后安装在尤斯灌流小室中。测量短路电流（Isc）以指示跨组织的净主动离子转运。NA（≥10⁻⁸ M）和SOM（＞10⁻¹⁰ M）均导致Isc降低，表明离子吸收净增加。河豚毒素（10⁻⁷ M）可消除NA反应，并使SOM反应的幅度降低至20%。DMPP、5-HT和EFS均刺激神经，使Isc增加，且这些反应中的每一个均被NA和SOM显著减弱。（摘要截至于250字）
