Leander S, Brodin E, Håkanson R, Sundler F, Uddman R
Acta Physiol Scand. 1982 Aug;115(4):427-35. doi: 10.1111/j.1748-1716.1982.tb07101.x.
Substance P-immunoreactive nerve fibres were fairly numerous in the lower esophagus of the guinea-pig and cat but few in the pig. They were particularly numerous in the myenteric and submucosal plexuses but could be detected also in the circular and longitudinal smooth muscle and in the muscularis mucosae. Only in the cat were SP-immunoreactive cell bodies detected, albeit in low number, in the myenteric plexus. Radioimmunoassay showed that the lower part of the cat esophagus contained approximately 10 times more immunoreactive SP than the upper part and that the muscle layer contained more SP than the mucosa. Motor effects of synthetic SP were studied on segments from circular smooth muscle of cat esophagus. SP contracted the smooth muscle and enhanced the response to electrical stimulation. These effects of SP could be blocked by the specific SP antagonist (D-Pro2, D-Trp7, 9)-SP. The contractile response to electrical stimulation could be blocked by the cholinergic muscarinic blocker atropine and the opiate receptor agonist leu-enkephalin but not by the SP antagonist or by adrenergic blockers. Hence, the results suggest that cholinergic neurons innervate the circular smooth muscle, and that opiate receptor agonists suppress transmission in these neurons. Neuronal SP in the esophagus may serve to enhance the contractile responses of esophageal smooth muscle.
P物质免疫反应性神经纤维在豚鼠和猫的食管下段相当多，但在猪的食管下段则很少。它们在肌间神经丛和黏膜下神经丛中特别多，但在环形和纵行平滑肌以及黏膜肌层中也能检测到。仅在猫的肌间神经丛中检测到了P物质免疫反应性细胞体，尽管数量很少。放射免疫分析表明，猫食管下段的免疫反应性P物质含量比上段大约多10倍，而且肌层中的P物质含量比黏膜中的多。研究了合成P物质对猫食管环形平滑肌节段的运动效应。P物质使平滑肌收缩，并增强了对电刺激的反应。P物质的这些效应可被特异性P物质拮抗剂（D-脯氨酸2，D-色氨酸7，9）-P物质阻断。对电刺激的收缩反应可被胆碱能毒蕈碱受体阻断剂阿托品和阿片受体激动剂亮氨酸脑啡肽阻断，但不能被P物质拮抗剂或肾上腺素能阻断剂阻断。因此，结果表明胆碱能神经元支配环形平滑肌，而且阿片受体激动剂抑制这些神经元中的传递。食管中的神经P物质可能有助于增强食管平滑肌的收缩反应。
