Goedert M, Hunter J C, Ninkovic M
Nature. 1984;311(5981):59-62. doi: 10.1038/311059a0.
Neurotensin is a 13-amino acid peptide that is widely distributed in central and peripheral tissues of various mammalian species. In peripheral tissues, the highest concentration of neurotensin-like immunoreactivity is found in the ileum, where it is present in endocrine-like cells and nerve fibres. The longitudinal smooth muscle layer of the guinea pig ileum, where neurotensin has both a direct relaxant and an indirect contractile action, has been used extensively as a biological assay system for neurotensin. We report here that the majority of specific 3H-neurotensin binding sites is present in the guinea pig ileum circular smooth muscle layer, which is known to be innervated by a large proportion of the ileal non-adrenergic inhibitory nerves. Neurotensin produces a dose-dependent, tetrodotoxin-resistant relaxation, whereas the relaxation produced by field stimulation of the inhibitory nerves is frequency-dependent and tetrodotoxin-sensitive. The calcium-dependent potassium channel blocker apamin inhibits both the neurotensin- and nerve stimulation-induced muscle relaxation. Incubation of the circular smooth muscle preparation with a neurotensin antiserum substantially inhibited the nerve stimulation-induced relaxation, indicating a direct relationship between the effects of neurotensin and of nerve stimulation.
神经降压素是一种由13个氨基酸组成的肽，广泛分布于各种哺乳动物的中枢和外周组织中。在外周组织中，神经降压素样免疫反应性的最高浓度出现在回肠，它存在于类内分泌细胞和神经纤维中。豚鼠回肠的纵行平滑肌层，神经降压素在其中既有直接舒张作用又有间接收缩作用，已被广泛用作神经降压素的生物检测系统。我们在此报告，大多数特异性3H-神经降压素结合位点存在于豚鼠回肠环行平滑肌层，已知该层由大部分回肠非肾上腺素能抑制神经支配。神经降压素产生剂量依赖性、对河豚毒素耐药的舒张作用，而通过抑制神经的场刺激产生的舒张作用是频率依赖性的且对河豚毒素敏感。钙依赖性钾通道阻滞剂蜂毒明肽抑制神经降压素和神经刺激诱导的肌肉舒张。用神经降压素抗血清孵育环行平滑肌制剂可显著抑制神经刺激诱导的舒张，表明神经降压素和神经刺激的作用之间存在直接关系。
