Wang Z Y, Håkanson R
Department of Pharmacology, Lund University, Sweden.
Regul Pept. 1993 Apr 8;44(3):269-75. doi: 10.1016/0167-0115(93)90136-v.
Tachykinin analogues, claimed to be selective NK1, NK2 and NK3 receptor agonists, contracted the isolated rabbit iris sphincter muscle in a concentration-dependent manner. The contractions were not modified by the enkephalinase inhibitor thiorphan and the angiotensin-converting enzyme inhibitor captopril (10(-5) M of each). The pD2 values for (Sar9,Met(O2)11)SP (NK1 receptor agonist), (Nle10)NKA(4-10) (NK2 receptor agonist) and (MePhe7)NKB (NK3 receptor agonist) were 8.3, 6.1 and 8.2, respectively. (Sar9,Met(O2)11)SP was the most efficacious of the three agonists. The results are compatible with the presence of NK1 and NK3 receptors. The low pD2 value for the NK2 agonist may reflect a lack of NK2 receptors and interaction of the NK2 agonist with NK1 receptors. The contraction caused by the NK1 receptor agonist was inhibited competitively by the highly selective NK1 receptor antagonist (+/-) CP-96,345; the pA2 value was 5.5. Also the contraction caused by the NK2 receptor agonist was inhibited competitively by (+/-) CP-96,345 with a pA2 value of 5.7, supporting the view that the two agonists (Sar9,Met(O2)11)SP and (Nle10)NKA(4-10) interact with the same receptor. The selective NK2 receptor antagonist actinomycin D did not affect the contraction caused by the NK2 receptor agonist. We conclude that the rabbit iris sphincter muscle contains NK1 and probably NK3 receptors. We obtained no evidence for the presence of NK2 receptors.
速激肽类似物据称是选择性NK1、NK2和NK3受体激动剂，能以浓度依赖性方式使离体兔虹膜括约肌收缩。脑啡肽酶抑制剂噻奥芬和血管紧张素转换酶抑制剂卡托普利（各10⁻⁵ M）均未改变这种收缩。(Sar9,Met(O2)11)SP（NK1受体激动剂）、(Nle10)NKA(4 - 10)（NK2受体激动剂）和(MePhe7)NKB（NK3受体激动剂）的pD2值分别为8.3、6.1和8.2。(Sar9,Met(O2)11)SP是三种激动剂中最有效的。这些结果与NK1和NK3受体的存在相符。NK2激动剂的低pD2值可能反映缺乏NK2受体以及NK2激动剂与NK1受体的相互作用。NK1受体激动剂引起的收缩被高度选择性的NK1受体拮抗剂(+/-) CP - 96,345竞争性抑制；pA2值为5.5。同样，NK2受体激动剂引起的收缩也被(+/-) CP - 96,345竞争性抑制，pA2值为5.7，这支持了两种激动剂(Sar9,Met(O2)11)SP和(Nle10)NKA(4 - 10)与同一受体相互作用的观点。选择性NK2受体拮抗剂放线菌素D不影响NK2受体激动剂引起的收缩。我们得出结论，兔虹膜括约肌含有NK1受体，可能还含有NK3受体。我们没有获得存在NK2受体的证据。
