Spring C, Mevissen M, Reist M, Zulauf M, Steiner A
Department of Clinical Veterinary Medicine, Clinic for Ruminants Institute of Veterinary Pharmacology, University of Bern, Bern, Switzerland.
J Vet Pharmacol Ther. 2003 Oct;26(5):377-85. doi: 10.1046/j.1365-2885.2003.00500.x.
The effects of serotonin (5-hydroxytryptamine, 5-HT), a 5-HT2-receptor agonist, alpha-methyl-5-hydroxytryptamine (alpha-M-5-HT) and RS-67506, a 5-HT4 receptor partial agonist, on spontaneous contractility of bovine abomasal smooth muscle preparations were investigated in vitro. Preparations from the abomasal antrum of freshly slaughtered healthy dairy cows were cut parallel to the longitudinal fibres, suspended in isolated organ baths, and concentration-response curves were performed by cumulative application of the 5-HT receptor agonists. Blockade of 5-HT2-induced response was tested with atropine and hexamethonium. Serotonin evoked a significant increase in the area under curve (AUC), whilst the 5-HT2 receptor agonist alpha-M-5-HT significantly increased the AUC and resting tone (RT). RS-67506 induced a significant increase in AUC and RT and a significant decrease in the maximum force. The effect of alpha-M-5-HT was mediated by a muscarinic cholinergic pathway, as the effect of alpha-M-5-HT was inhibited in the presence of atropine but not hexamethonium. It is concluded that 5-HT2 and 5-HT4 receptors are present in the bovine abomasal antrum. Muscarinic receptors are involved in the increase in RT seen after 5-HT2 receptor stimulation.
在体外研究了5-羟色胺（5-羟色胺，5-HT）、5-HT2受体激动剂α-甲基-5-羟色胺（α-M-5-HT）和5-HT4受体部分激动剂RS-67506对牛皱胃平滑肌制剂自发收缩性的影响。从刚宰杀的健康奶牛皱胃窦部取下的组织块，沿纵行纤维平行切割，悬挂于离体器官浴槽中，通过累积应用5-HT受体激动剂绘制浓度-反应曲线。用阿托品和六甲铵测试5-HT2诱导反应的阻断情况。5-羟色胺引起曲线下面积（AUC）显著增加，而5-HT2受体激动剂α-M-5-HT显著增加AUC和静息张力（RT）。RS-67506使AUC和RT显著增加，最大张力显著降低。α-M-5-HT的作用由毒蕈碱胆碱能途径介导，因为在阿托品存在下α-M-5-HT的作用受到抑制，但六甲铵存在时不受抑制。得出结论：5-HT2和5-HT4受体存在于牛皱胃窦部。毒蕈碱受体参与5-HT2受体刺激后所见的RT增加。
