Yongsiri A, Takeuchi H, Kubota I, Muneoka Y
Department of Physiology, Gifu University School of Medicine, Japan.
Eur J Pharmacol. 1989 Nov 21;171(2-3):159-65. doi: 10.1016/0014-2999(89)90104-0.
Among several identifiable neurones of Achatina fulica Férussac, RAPN (right anterior pallial neurone) was sensitive to the two Mytilus inhibitory peptides (MIPs), H-Gly-Ser-Pro-Met-Phe-Val-NH2 ([Ser2]MIP) and H-Gly-Ala-Pro-Met-Phe-Val-NH2 ([Ala2]MIP), and their fragments, H-Pro-Met-Phe-Val-NH2 (MIP-(3-6)) and H-Met-Phe-Val-NH2 (MIP-(4-6)). These peptides, applied either locally by pneumatic pressure or in the bath, produced a slow outward current with an increase in membrane conductance. The other two related peptides, H-Gly-Ala-Pro-Met-Val-Phe-NH2 ([Ala2, Val5, Phe6]MIP-NH2) and H-Gly-Ala-Pro-Met-NH2 ([Ala2]MIP-(1-4)-NH2), were ineffective. The potency order of the four effective peptides was determined from their dose-response relations: [Ser2]MIP greater than [Ala2]MIP greater than MIP-(3-6) greater than MIP-(4-6). The ED50 of [Ser2]MIP was about 3 X 10(-5) M. Relations between the outward current (nA) and the conductance increase (microseconds) produced by the four peptides were quite linear (Y = 0.03416 X-0.01083, r = 0.98677). The reversal potentials for [Ser2]MIP (ES-MIP) measured with various extracellular K+ concentrations ([K+]0) were fitted to the Nernst equation, being identical with EK. ES-MIP was not affected by changing [Na+]0 and [Cl-]0.
在几种可识别的非洲大蜗牛（Achatina fulica Férussac）神经元中，右前脑叶神经元（RAPN）对两种贻贝抑制肽（MIPs）、H-Gly-Ser-Pro-Met-Phe-Val-NH2（[Ser2]MIP）和H-Gly-Ala-Pro-Met-Phe-Val-NH2（[Ala2]MIP）及其片段H-Pro-Met-Phe-Val-NH2（MIP-(3-6)）和H-Met-Phe-Val-NH2（MIP-(4-6)）敏感。这些肽通过气压局部施加或在浴液中施加时，会产生缓慢的外向电流，并伴有膜电导增加。另外两种相关肽H-Gly-Ala-Pro-Met-Val-Phe-NH2（[Ala2, Val5, Phe6]MIP-NH2）和H-Gly-Ala-Pro-Met-NH2（[Ala2]MIP-(1-4)-NH2）则无效。根据四种有效肽的剂量-反应关系确定了它们的效价顺序：[Ser2]MIP＞[Ala2]MIP＞MIP-(3-6)＞MIP-(4-6)。[Ser2]MIP的半数有效剂量（ED50）约为3×10^(-5) M。四种肽产生的外向电流（nA）与电导增加（微秒）之间的关系相当线性（Y = 0.03416X - 0.01083，r = 0.98677）。用不同细胞外钾离子浓度（[K+]0）测量的[Ser2]MIP的反转电位（ES-MIP）符合能斯特方程，与EK相同。ES-MIP不受[Na+]0和[Cl-]0变化的影响。
