Thorbøll J E, Bindslev N, Hansen M B, Schmidt P, Skadhauge E
Department of Anatomy and Physiology, The Royal Veterinary and Agricultural University, Frederiksberg, Denmark.
Eur J Pharmacol. 1998 Oct 23;359(2-3):271-9. doi: 10.1016/s0014-2999(98)00650-5.
In the present study, tachykinin receptors (designated NK 1, NK2 and NK3) involved in regulation of ion transport in porcine jejunum were characterised. Stripped tissue preparations were mounted in Ussing chambers and short-circuited. Substance P produced a concentration dependent increase in short-circuit current, the relationship showing a double sigmoidal form. The non-peptide NK1 receptor antagonist, CP 99,994 ((2S,3S)-3-(2-methoxybenzyl)amino-2-phenylpiperidine), caused a dextral shift of the first sigmoidal response, indicating the involvement of an NK1 receptor. This was further supported by a concentration-dependent response of the NK1 receptor agonist [Sar9Met(O2)11]substance P with an EC50 value of 235.0+/-53.9 nM. Increasing concentrations of CP 99,994 (0.1, 0.3 and 1 microM) produced a parallel dextral shift of the [Sar9Met(O2)11]substance P curve with a slope of the Schild regression significantly different from unity (1.59). The neurokinin A concentration-response curve, with an EC50 value of 68.87+/-16.23 nM, was not significantly changed by the non-peptide NK2 receptor antagonist SR 48,968 ((S)-N-methyl-N-(4-(4-acetylamino-4-phenylpiperidino)-2-(3,4-dichlorophe nyl)butyl)bezamide). In additional studies, the peptide NK2 receptor antagonists, GR 94,800 (PhCO-Ala-Ala-DTrp-Phe-DPro-Pro-NleNH2) and PD 147,714 ((2,3-diOMeZ)-(S)Trp(S)alphaMePheGlyNH2), did not change the response to neurokinin A. However, CP 99,994 totally inhibited neurokinin A responses at 0.5 microM and above. The NK2 receptor agonist, [beta-Ala8]neurokinin A-(4-10), caused only an increase in short-circuit current in microM concentrations, whereas the NK3 receptor agonist, senktide, did not elicit a response. These results indicate, that substance P and neurokinin A mediate ion transport in porcine jejunum through NK1 receptors. However, tachykinins seem to activate another receptor. Two active conformers of the NK1 receptor might be present.
在本研究中，对参与猪空肠离子转运调节的速激肽受体（命名为NK1、NK2和NK3）进行了特性分析。将剥离的组织标本安装在尤斯灌流小室中并使其短路。P物质使短路电流呈浓度依赖性增加，该关系呈双S形。非肽类NK1受体拮抗剂CP 99,994（(2S,3S)-3-(2-甲氧基苄基)氨基-2-苯基哌啶）使第一个S形反应向右移位，表明有NK1受体参与。NK1受体激动剂[Sar9Met(O2)11]P物质的浓度依赖性反应进一步支持了这一点，其EC50值为235.0±53.9 nM。CP 99,994浓度增加（0.1、0.3和1 microM）使[Sar9Met(O2)11]P物质曲线产生平行的向右移位，Schild回归斜率显著不同于1（1.59）。神经激肽A的浓度-反应曲线，其EC50值为68.87±16.23 nM，未被非肽类NK2受体拮抗剂SR 48,968（(S)-N-甲基-N-(4-(4-乙酰氨基-4-苯基哌啶基)-2-(3,4-二氯苯基)丁基)苯甲酰胺）显著改变。在进一步的研究中，肽类NK2受体拮抗剂GR 94,800（苯甲酰-Ala-Ala-DTrp-Phe-DPro-Pro-NleNH2）和PD 147,714（(2,3-二甲氧基苄基)-(S)Trp(S)α-甲基苯丙氨酸甘氨酰胺）未改变对神经激肽A的反应。然而，CP 99,994在0.5 microM及以上浓度时完全抑制了神经激肽A的反应。NK2受体激动剂[β-Ala8]神经激肽A-(4-10)仅在 microM浓度时使短路电流增加，而NK3受体激动剂速激肽则未引发反应。这些结果表明，P物质和神经激肽A通过NK1受体介导猪空肠中的离子转运。然而，速激肽似乎激活了另一种受体。可能存在NK1受体的两种活性构象。
