神经降压素对家兔离体空肠收缩的影响及机制

Effects and mechanism of neurotensin on contractile activity of isolated jejunal smooth muscles in rabbits

采用离体肠管灌流法 ,研究神经降压素 (neurotensin ,NT)对家兔离体空肠平滑肌收缩的影响 ,并探讨其作用机制。结果 :①微量NT即可影响空肠的收缩活动 ,NT对空肠收缩的影响是双相的 ,即先抑制后兴奋作用 ,并呈明显的量效依赖关系。②纳洛酮可完全阻断NT对空肠平滑肌的抑制后兴奋作用 (P >0 0 1)。③TTX、phentolamine、心得安和阿托品皆不影响NT对空肠平滑肌的作用 (P <0 0 5 )。结果提示 :NT可能直接作用于空肠平滑肌膜上的NT敏感受体 ;空肠平滑肌上兴奋性NT敏感受体的结构与阿片受体相关。

WT5”BZ] To study the effects and mechanism of NT on the contraction of isolated jejunal smooth muscles in rabbits,experiments were performed by using isolated intestinal perfusion technique.The results showed that:①NT in nanomolar concentrations caused a biphasic effect in isolated jejunal muscle spontaneous contractile activity,i.e. the inhibitory phase was followed by an excitatory phase.The effects were dose-dependent. ②Naloxone almost completely abolished the “rebound”contraction of jejunal smooth muscle induced by NT. ③TTX,phentolamine,propranolol and atropine had no effect on NT induced contraction change of isolated rabbit jejunal smooth muscles.These suggest that NT may act on the contraction of isolated rabbit jejunal smooth muscles by a direct action on NT sensitive receptor on the smooth muscle.The structure of excitatory NT-sensitive receptor on jejunal smooth muscle may be associated with opiate receptor. [WT5”HZ]