Evans P D, Reale V, Merzon R M, Villegas J
Department of Zoology, University of Cambridge, United Kingdom.
Glia. 1990;3(5):393-404. doi: 10.1002/glia.440030511.
Substance P produced a dose-dependent, long-lasting hyperpolarization of the membrane of the Schwann cells of the giant nerve fibre of the tropical squid. A survey of the effectiveness of a range of other naturally occurring tachykinin agonists suggested that the receptors present on the squid Schwann cell belong to the subtype SP-P or NK1, for which substance P is the preferred agonist. A survey of the effectiveness of a range of substance P fragments indicated that the direct hyperpolarizing effects of the substance P molecule were mediated by peptides with an intact amidated C-terminal. However, a second subset of receptors that can be activated by N-terminal fragments and analogues lacking an amidated C-terminal was also present in this preparation. The non-subtype-specific antagonist D-Arg1,D-Trp7,9,Leu11 substance P (spantide) was a potent blocker of the effects of substance P in this preparation. Activation of the substance P receptors did not interact with the effects induced by activation of either the nicotinic cholinergic receptors or octopaminergic receptors present in this preparation. However, it did potentiate the effects of activation of the receptors for vasoactive intestinal peptide (VIP), either in response to bath application of the peptide or due to their activation by the release of an endogenous VIP-like peptide after stimulation of the giant axon.
P物质使热带鱿鱼巨大神经纤维的施万细胞膜产生剂量依赖性的持久超极化。对一系列其他天然存在的速激肽激动剂有效性的研究表明，鱿鱼施万细胞上存在的受体属于SP-P或NK1亚型，P物质是该亚型的首选激动剂。对一系列P物质片段有效性的研究表明，P物质分子的直接超极化作用是由具有完整酰胺化C末端的肽介导的。然而，该制剂中还存在另一类可被N末端片段和缺乏酰胺化C末端的类似物激活的受体。非亚型特异性拮抗剂D-Arg1、D-Trp7,9、Leu11 P物质（spantide）是该制剂中P物质作用的有效阻滞剂。P物质受体的激活与该制剂中存在的烟碱型胆碱能受体或章鱼胺能受体激活所诱导的效应不相互作用。然而，无论是通过在浴中应用该肽，还是由于刺激巨大轴突后内源性VIP样肽的释放激活这些受体，它确实增强了血管活性肠肽（VIP）受体激活的效应。
