Honda H, Sakai Y, Iwata T, Ohba S, Kanezuka T, Irino O
Biological Section, Grelan Pharmaceutical Co., Ltd., Tokyo, Japan.
Arch Int Pharmacodyn Ther. 1988 Mar-Apr;292:112-21.
The effect of ifenprodil tartrate (IFT) on 2 subtypes of postsynaptic alpha 1- and alpha 2-adrenoceptors was investigated. For this purpose, changes in the tension of isolated canine saphenous veins were measured isometrically, and Ca2+ uptake in these veins was also measured. IFT displaced the dose-contractile response curves for phenylephrine and clonidine in a competitive manner, and the activity sequence of antagonists against phenylephrine was IFT greater than phentolamine greater than prazosin greater than yohimbine. On the other hand, the activity sequence of antagonists against clonidine was IFT greater than phentolamine greater than yohimbine greater than prazosin. The effect of IFT as well as that of phentolamine were different from the other antagonists and of approximately the same specific activities against both agonists. The IFT-induced relaxations of the veins contracted by phenylephrine and clonidine were relatively unchanged in both normal and Ca2+-free solutions. IFT inhibited phenylephrine- and clonidine-induced Ca2+ uptake in the saphenous veins. The results suggest that IFT does not possess a relative selectivity toward postsynaptic alpha 1- and alpha 2-adrenoceptors, and that these actions reflect the vasorelaxing effects on phenylephrine- and clonidine-induced contraction in the canine saphenous veins.
研究了酒石酸艾芬地尔（IFT）对突触后α1和α2肾上腺素能受体2种亚型的作用。为此，等长测量了离体犬隐静脉的张力变化，并测定了这些静脉中的Ca2+摄取。IFT以竞争性方式使去氧肾上腺素和可乐定的剂量-收缩反应曲线发生位移，且拮抗剂对去氧肾上腺素的活性顺序为IFT＞酚妥拉明＞哌唑嗪＞育亨宾。另一方面，拮抗剂对可乐定的活性顺序为IFT＞酚妥拉明＞育亨宾＞哌唑嗪。IFT以及酚妥拉明的作用不同于其他拮抗剂，且对两种激动剂的比活性大致相同。在正常溶液和无Ca2+溶液中，IFT对去氧肾上腺素和可乐定所致静脉收缩的舒张作用相对不变。IFT抑制去氧肾上腺素和可乐定诱导的隐静脉Ca2+摄取。结果表明，IFT对突触后α1和α2肾上腺素能受体不具有相对选择性，且这些作用反映了其对犬隐静脉中去氧肾上腺素和可乐定诱导的收缩的血管舒张作用。
