Maggi C A, Catalioto R M, Criscuoli M, Cucchi P, Giuliani S, Lecci A, Lippi A, Meini S, Patacchini R, Renzetti A R, Santicioli P, Tramontana M, Zagorodnyuk V, Giachetti A
Department of Neuromuscular Physiology, Bogomoletz Institute of Physiology, Kiev, Ukraine.
Can J Physiol Pharmacol. 1997 Jun;75(6):696-703.
Substance P (SP) and neurokinin A (NKA) are synthesized by enteric cholinergic motorneurons that project to the longitudinal and circular muscle of the mammalian intestine. Thus, acetylcholine, SP, and NKA are the excitatory neuromuscular transmitters in the intestine. Tachykinin NK1 and NK2 receptors are expressed by smooth muscle cells in most regions of the intestine: the corelease of SP and NKA from nerves thus realizes paradigms of tachykininergic cotransmission. Examples have been found in which a cooperative model can be applied to account for the action of SP-NKA acting at NK1 and NK2 receptors (e.g., circular muscle of guinea-pig duodenum), as well as examples in which the message produced by activation of the two receptors diverges sharply in producing responses that have a markedly different time course and use different effector systems (e.g., circular muscle of guinea-pig colon). NK3 receptors are expressed on both excitatory and inhibitory motor neurons: indirect contractions (via release of acetylcholine and tachykinins) and relaxations (via release of nitric oxide) can be evoked in the gut by selective stimulation of NK3 receptors. Although a role of NK3 receptors in certain enteric reflexes has been evidenced, the importance of this system in mediating hexamethonium-resistant enteric transmission appears less important than previously speculated.
P物质（SP）和神经激肽A（NKA）由投射至哺乳动物肠道纵肌和环肌的肠胆碱能运动神经元合成。因此，乙酰胆碱、SP和NKA是肠道中的兴奋性神经肌肉递质。速激肽NK1和NK2受体在肠道大部分区域的平滑肌细胞中表达：神经释放的SP和NKA共同实现了速激肽能共同传递模式。已发现一些例子，其中协同模型可用于解释SP-NKA作用于NK1和NK2受体的作用（例如豚鼠十二指肠环肌），也有例子表明，激活这两种受体产生的信息在产生具有明显不同时间进程和使用不同效应系统的反应时差异很大（例如豚鼠结肠环肌）。NK3受体在兴奋性和抑制性运动神经元上均有表达：选择性刺激NK3受体可在肠道中诱发间接收缩（通过释放乙酰胆碱和速激肽）和舒张（通过释放一氧化氮）。尽管已证明NK3受体在某些肠反射中起作用，但该系统在介导六甲铵抗性肠传递中的重要性似乎不如先前推测的那么重要。
