Glusa E, Markwardt F
Pharmacology. 1984;29(6):336-42. doi: 10.1159/000138033.
5-Hydroxytryptamine (5-HT) caused concentration-dependent contractions in human postmortem femoral venous and arterial strips. In veins, it was a more potent agonist than noradrenaline, while the reverse was true for arteries. Pizotifen and methysergide were competitive antagonists against 5-HT in femoral arteries with pA2 values of 8.18 and 8.37, while in femoral veins they exerted noncompetitive antagonism. Dihydroergotamine (DHE) antagonized the 5-HT effect in a manner which was not competitive both in veins and arteries. At concentrations employed in antagonist experiments, it increased the resting tone, particularly in veins. The contractile response of veins to DHE was inhibited when the vascular preparations were preincubated with pizotifen at nanomolar concentrations. The results suggest that 5-HT receptors on veins differ from those on arteries. DHE possesses comparatively high affinity for 5-HT receptors on veins. It is concluded that 5-HT receptors may be involved in the contractile response of veins to DHE.
5-羟色胺（5-HT）可引起人死后股静脉和动脉条带浓度依赖性收缩。在静脉中，它是比去甲肾上腺素更强效的激动剂，而在动脉中则相反。苯噻啶和麦角新碱在股动脉中是5-HT的竞争性拮抗剂，pA2值分别为8.18和8.37，而在股静脉中它们表现为非竞争性拮抗作用。双氢麦角胺（DHE）在静脉和动脉中均以非竞争性方式拮抗5-HT的作用。在拮抗剂实验中所使用的浓度下，它会增加静息张力，尤其是在静脉中。当血管标本用纳摩尔浓度的苯噻啶预孵育时，静脉对DHE的收缩反应受到抑制。结果表明，静脉上的5-HT受体与动脉上的不同。DHE对静脉上的5-HT受体具有较高的亲和力。结论是5-HT受体可能参与了静脉对DHE的收缩反应。
