A recently described peptide tachykinin (NK1) receptor antagonist, FK 888, was found to inhibit the electrically-evoked, tachykinin-mediated contractile responses of the rabbit iris sphincter in a concentration-dependent manner; the pIC50 value was 6.6 +/- 0.08. 2. Contractions induced by a selective NK1 receptor agonist, [Sar9,Met(O2)11]substance P, were inhibited competitively by FK 888; the pKB value was 7.1. 3. FK 888 (1 nM-100 microM) was without effect on the electrically-evoked, cholinergic response of the rabbit iris sphincter and the electrically-evoked, sympathetic response of the guinea-pig vas deferens. The contractions of the rabbit iris sphincter, induced by either carbachol (10 nM-30 microM) or noradrenaline (0.1-100 microM), were not affected by 10 microM FK 888. 4. FK 888 (1-30 microM) did not induce histamine release from rat peritoneal mast cells. 5. FK 888 (33 and 333 microM) was without effect on the electrically-evoked action potentials of the frog sciatic nerve. Thus, FK 888 is a moderately high affinity and selective tachykinin (NK1) receptor antagonist.
摘要
最近描述的一种肽速激肽(NK1)受体拮抗剂FK 888,被发现能以浓度依赖的方式抑制兔虹膜括约肌由电诱发的、速激肽介导的收缩反应;pIC50值为6.6±0.08。2. 选择性NK1受体激动剂[Sar9,Met(O2)11]P物质诱导的收缩,被FK 888竞争性抑制;pKB值为7.1。3. FK 888(1 nM - 100 μM)对兔虹膜括约肌的电诱发胆碱能反应以及豚鼠输精管的电诱发交感反应均无影响。由卡巴胆碱(10 nM - 30 μM)或去甲肾上腺素(0.1 - 100 μM)诱导的兔虹膜括约肌收缩,不受10 μM FK 888的影响。4. FK 888(1 - 30 μM)不会诱导大鼠腹膜肥大细胞释放组胺。5. FK 888(33和333 μM)对蛙坐骨神经的电诱发动作电位无影响。因此,FK 888是一种具有中等高亲和力的选择性速激肽(NK1)受体拮抗剂。