抽象
从胚胎肺的终端气道原位或外植体表现出节奏的自发性收缩。我们的目标是看看在第一个妊娠期胎儿的整个支气管树中发生气道的缩小响应,如果是,则表征它们。支气管树是从20-35g猪胎儿的肺部(44-48天妊娠)的血管系统和实质植物。通过透射光直接可视化气道腔,通过视频成像显微镜实时记录变窄。From the main stem bronchi to the terminal regions of late generation branches (20-35 microns i.d.) strong bronchoconstrictor responses to micromolar concentrations of acetylcholine (ACh), histamine, substance P and K+ depolarizing solution were seen, whilst inhibition of narrowing with beta-adrenoceptor agonists was evidence of beta-receptors on the smooth muscle. Moreover, strong narrowing responses to electrical field stimulation, which were blocked by atropine, indicated that functional cholinergic nerves were present. A remarkable display of spontaneous narrowing in the airways of many of the bronchial tree preparations caused the movement of lung liquid to and fro. We speculate that the bronchomotor tone and associated spontaneous activity, which move the lung fluid along the airways, serve to maintain an even positive pressure in localized areas of the bronchial tree which is essential to provide the stimulus for continued growth of the lung.