P物质对大鼠胃窦肌条收缩活动的影响及其机制探讨

EFFECT AND ITS MECHANISM OF SUBSTANCE P ON CONTRACTILE ACTIVITY OF ISOLATED ANTRAL MUSCLE STRIPS OF RAT

本文利用器官浴槽孵育离体大鼠胃窦肌条，观察Ｐ物质（ｓｕｂｓｔａｎｃｅＰ，ＳＰ）对肌条收缩的效应及多种拮抗剂或抑制剂对ＳＰ效应的影响。结果：（１）ＳＰ明显增强肌条收缩幅度，在剂量为８×１０－１１－８×１０－７ｍｏｌ范围内里剂量－效应关系。ＳＰ４×１０－８ｍｏｌ，使肌条收缩幅度增强１６０．９±２３．０％．与生理盐水组比较Ｐ＜０．００１。（２）神经节阻断剂六烃季胺、５－ＨＴ２受体阻断剂赛庚啶、Ｈ１受体阻断剂苯海拉明、磷酸二酯酶抑制剂氨茶碱使ＳＰ肌条收缩幅度增强效应明显减弱（Ｐ＜０．０５）。（３）阿托品、心得安、酚妥拉明、氟哌啶醇和纳洛酮预孵育后，ＳＰ增强收缩幅度的效应与单独ＳＰ组相比差异无显著性。结果提示ＳＰ可能是肠神经系统中的非胆碱能兴奋性递质，可能通过激活５－ＨＴ神经元、促使组织胺释放等途径而增强肌条的收缩幅度。

The present study was aimed at investigsting the effect of substance P(SP) on the contractile activity of isolated antral muscle strips of rat and its underlying mechanism. Isolated stripe were incubated in an organ bath into which SP was added with or without pretreatment of some antagonists or inhibitors. The results were as follows: (1) SP increased the contractile amplitude of the strips in a dose-dependent manner from 8×10-11 to 8×10-7 mol. At 4×10-8 mol the amplitude was increased by 160. 9 ±23. 0%, while the automaticity of the strias was not affected. (2) This effect of SP could be partially inhibited by hexamethonium (ganglionic blocker), cyproheptadine(blocker of 5-HT2 receptor), diphenhydramine (blocker of H1 receptor), or aminophylline(inhibitor of phosphodiesterase), but not by atropine, propranolol, phentolamine, haloperidol, or naloxone. These results suggeSted that SP might be a noncholinergic excitatory transmitter. Its spasmogenic action might be mediated by activat ing 5-HT neurons, which elicited release of histumine or directly acted on muscle cells.