Martínez-Cuesta M A, Barrachina M D, Moreno L, Calatayud S, Esplugues J
Department of Pharmacology, Faculty of Medicine, University of Valencia, Spain.
J Pharm Pharmacol. 1996 Sep;48(9):955-8. doi: 10.1111/j.2042-7158.1996.tb06010.x.
The present study characterizes the nature of the response to the platelet-activating factor (PAF) in isolated gastric corpus with and without mucosa. PAF (10(-8) M) induced contraction of rat isolated gastric corpus strips followed by desensitization of this tissue. Incubation of strips with the specific PAF-receptor antagonist WEB 2086 (5 x 10(-8) -5 x 10(-5) M) the prostaglandin blocker indomethacin (10(-6) M) and the 5-hydroxytryptamine antagonist methysergide (10(-5) M) reduced significantly the contraction induced by PAF. Neither of the histamine H1/H2 antagonists diphenhydramine (10(-6) M) or cimetidine (10(-5) M) affected the contraction induced by PAF. In contrast with the whole gastric corpus, in mucosa-free strips, the contractile effect of PAF was not modified by methysergide. The present study supports the view that the effect of PAF is mediated by activation of specific PAF receptors and the release of prostaglandins and 5-hydroxytryptamine in isolated gastric corpus. Furthermore, our results suggest a role of the gastric mucosa via the release of 5-hydroxytryptamine which contributes to the contractile effect of PAF in the gastric smooth muscle.
本研究描述了在有黏膜和无黏膜的离体胃体中，对血小板活化因子（PAF）的反应性质。PAF（10^(-8) M）可诱导大鼠离体胃体条收缩，随后该组织出现脱敏现象。将胃体条与特异性PAF受体拮抗剂WEB 2086（5×10^(-8) - 5×10^(-5) M）、前列腺素阻断剂吲哚美辛（10^(-6) M）以及5-羟色胺拮抗剂甲基麦角新碱（10^(-5) M）一起孵育，可显著降低PAF诱导的收缩。组胺H1/H2拮抗剂苯海拉明（10^(-6) M）或西咪替丁（10^(-5) M）均不影响PAF诱导的收缩。与完整胃体相反，在无黏膜的胃体条中，甲基麦角新碱不改变PAF的收缩效应。本研究支持以下观点：PAF的作用是通过激活特异性PAF受体以及在离体胃体中释放前列腺素和5-羟色胺来介导的。此外，我们的结果表明胃黏膜通过释放5-羟色胺发挥作用，这有助于PAF对胃平滑肌的收缩效应。
