Lawson Health Research Institute, University of Western Ontario, London, Canada.
Biophys Chem. 2011 Oct;158(2-3):119-25. doi: 10.1016/j.bpc.2011.06.001. Epub 2011 Jun 13.
Pulmonary surfactant facilitates breathing by forming a surface tension reducing film at the air-liquid interface of the alveoli. The objective was to characterize the structure of surfactant films using endogenous rat surfactant. Solid-support surfactant films, at different surface pressures, were obtained using a Langmuir balance and were analyzed using atomic force microscopy. The results showed a lipid film structure with three distinct phases: liquid expanded, liquid ordered and liquid condensed. The area covered by the liquid condensed domains increased as surface pressure increased. The presence of liquid ordered phase within these structures correlated with the cholesterol content. At a surface pressure of 50 mN/m, stacks of bilayers appeared. Several structural details of these films differ from previous observations made with goat and exogenous surfactants. Overall, the data indicate that surfactant films demonstrate phase separation at low surface pressures and multilayer formation at higher pressure, features likely important for normal surfactant function.
肺表面活性剂通过在肺泡的气液界面形成降低表面张力的膜来促进呼吸。本研究的目的是使用内源性大鼠肺表面活性剂来表征表面活性剂膜的结构。使用 Langmuir 天平获得不同表面压力下的固支表面活性剂膜，并使用原子力显微镜进行分析。结果表明，脂质膜具有三种明显的相：液体膨胀相、液体有序相和液体凝聚相。随着表面压力的增加，液体凝聚区的覆盖面积增加。这些结构中存在的液体有序相与胆固醇含量相关。在表面压力为 50 mN/m 时，出现了双层堆栈。这些膜的一些结构细节与之前用山羊和外源性表面活性剂观察到的结果不同。总的来说，这些数据表明，表面活性剂膜在低表面压力下表现出相分离，在较高压力下表现出多层形成，这是正常表面活性剂功能的重要特征。
