Fasth S, Hedlund H, Hultén L, Nordgren S, Oresland T
Acta Physiol Scand. 1983 Aug;118(4):329-36. doi: 10.1111/j.1748-1716.1983.tb07279.x.
The effects of 5-HT on proximal colonic and rectal motility and total colonic blood flow were studied in anaesthetized cats and compared with those evoked by pelvic nerve stimulation. Vasodilator responses, consistently elicited by low doses (5-10 micrograms/min close i.a.) and intermediate doses (10-50 micrograms/min) of 5-HT were invariably abolished by hexamethonium indicating a nerve mediated response. Simultaneously to the vasodilator response both cholinergic and non-cholinergic hexamethonium sensitive non-adrenergic motility responses were evoked in the proximal colon. Furthermore non-cholinergic, non-adrenergic inhibitory neurons were excited. In the rectum excitation of such inhibitory neurons was the most consistent finding. The mechanisms behind the nerve mediated vascular and motility responses seem to differ as only the vascular effects were blocked by dihydroergotamine. The nerve mediated responses were in many respects similar to those evoked by pelvic nerve stimulation indicating that 5-HT exerts its effects on the same instrinsic neurons as the pelvic nerves. At intermediate and high doses (50-100 micrograms/min) the effects exerted on the instrinsic reflex arcs were modulated by direct effects on the smooth muscle.
在麻醉猫身上研究了5-羟色胺（5-HT）对近端结肠和直肠运动以及结肠总血流量的影响，并与盆腔神经刺激所引发的影响进行了比较。低剂量（5-10微克/分钟，腹腔内近距离注射）和中等剂量（10-50微克/分钟）的5-HT持续引发的血管舒张反应总是会被六甲铵消除，这表明这是一种神经介导的反应。在近端结肠，与血管舒张反应同时出现的是，胆碱能和非胆碱能的六甲铵敏感的非肾上腺素能运动反应被诱发。此外，非胆碱能、非肾上腺素能抑制性神经元被兴奋。在直肠，此类抑制性神经元的兴奋是最一致的发现。神经介导的血管和运动反应背后的机制似乎有所不同，因为只有血管效应被双氢麦角胺阻断。神经介导的反应在许多方面与盆腔神经刺激所引发的反应相似，这表明5-HT与盆腔神经作用于相同的内在神经元。在中等和高剂量（50-100微克/分钟）时，对内在反射弧的作用会受到对平滑肌的直接作用的调节。
