Kalkman H O, Van Gelderen E M, Timmermans P B, Van Zwieten P A
Eur J Pharmacol. 1982 Feb 19;78(1):107-11. doi: 10.1016/0014-2999(82)90377-6.
In pithed normotensive rats, the pressor effects evoked by i.v. serotonin (5-HT) and ergometrine were analysed using the relatively selective alpha 1-, alpha 2- and serotonin antagonists prazosin, yohimbine methysergide, respectively. The pressor response to ergometrine was reduced by both prazosin and yohimbine but only moderately affected by methysergide. On the other hand, the rise in diastolic pressure brought about by serotonin was strongly depressed by methysergide but not influenced by the blockade of either alpha 1- or alpha 2-adrenoceptors. The calcium antagonist nifedipine shifted the dose-pressor response curve of ergometrine to the right in a dose-related, non-parallel manner. The maximum pressor response was diminished by nifedipine. In contrast, the rise in pressure provoked by serotonin was not affected by nifedipine. The results thus show that in the pithed rat the vasoconstrictor response to ergometrine is mediated by alpha-adrenoceptors (both alpha 1 and alpha 2) rather than by serotonin receptors. These findings question the role of serotonin receptors in the vasoconstriction induced by ergometrine.
在脊髓横断的正常血压大鼠中，分别使用相对选择性的α1、α2肾上腺素能受体拮抗剂哌唑嗪、育亨宾以及5-羟色胺受体拮抗剂甲基麦角新碱，分析静脉注射5-羟色胺（5-HT）和麦角新碱所引起的升压效应。哌唑嗪和育亨宾均可降低对麦角新碱的升压反应，但甲基麦角新碱仅产生中度影响。另一方面，5-羟色胺引起的舒张压升高可被甲基麦角新碱强烈抑制，但不受α1或α2肾上腺素能受体阻断的影响。钙拮抗剂硝苯地平以剂量相关的非平行方式使麦角新碱的剂量-升压反应曲线右移。硝苯地平使最大升压反应减弱。相反，5-羟色胺引起的血压升高不受硝苯地平影响。结果表明，在脊髓横断大鼠中，麦角新碱的血管收缩反应是由α肾上腺素能受体（α1和α2）介导，而非5-羟色胺受体。这些发现对5-羟色胺受体在麦角新碱诱导的血管收缩中的作用提出了质疑。
