Burka J F, Blair R M, Hogan J E
Department of Anatomy and Physiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, P.E.I., Canada.
Can J Physiol Pharmacol. 1989 May;67(5):477-82. doi: 10.1139/y89-076.
The ability of carbachol and 5-hydroxytryptamine (5-HT) to contract isolated segments of rainbow trout intestine in a concentration-dependent manner indicates the presence of muscarinic and serotoninergic receptors in this tissue. The activity of these agonists appears to be directly on the smooth muscle, since ganglionic blockers and inhibitors of neurotransmission did not inhibit contractions. The carbachol-induced contractions were selectively inhibited by atropine and (+-)-3-quinuclidinyl xanthene-9-carboxylate hemioxalate hydrate, an M-2 muscarinic receptor antagonist. However, the inhibition was not competitive. McN-A-343, an M-1 muscarinic agonist had no effect on intrinsic tone. The 5-HT-induced contractions were selectively inhibited by methysergide and the 5-HT2 receptor blockers, ketanserin and 1-(1-naphthyl)piperazine. Again, the inhibition by these agents was not competitive. 5-HT1 and 5-HT3 receptor antagonists did not inhibit contractions. The results thus suggest that the smooth muscle of the rainbow trout intestine contains M-2 muscarinic and 5-HT2 receptors.
卡巴胆碱和5-羟色胺（5-HT）能使虹鳟鱼离体肠段呈浓度依赖性收缩，这表明该组织中存在毒蕈碱受体和5-羟色胺能受体。这些激动剂的活性似乎直接作用于平滑肌，因为神经节阻断剂和神经传递抑制剂并未抑制收缩。卡巴胆碱诱导的收缩被阿托品和M-2毒蕈碱受体拮抗剂（+-）-3-喹核醇基呫吨-9-羧酸半草酸盐一水合物选择性抑制。然而，这种抑制并非竞争性的。M-1毒蕈碱激动剂 McN-A-343对肠段的基础张力没有影响。5-HT诱导的收缩被甲基麦角新碱以及5-HT2受体阻滞剂酮色林和1-（1-萘基）哌嗪选择性抑制。同样，这些药物的抑制作用也不是竞争性的。5-HT1和5-HT3受体拮抗剂并未抑制收缩。因此，结果表明虹鳟鱼肠平滑肌含有M-2毒蕈碱受体和5-HT2受体。
