Mason R J, Williams M C, Widdicombe J H, Sanders M J, Misfeldt D S, Berry L C
Proc Natl Acad Sci U S A. 1982 Oct;79(19):6033-7. doi: 10.1073/pnas.79.19.6033.
Fluid and electrolyte transport by epithelial cells in vitro can be recognized by the ability of cultured cells to form domes and by the electrical properties of monolayer cultures. Pulmonary alveolar epithelial cells are thought to be partially responsible for fluid movement in the fetal lung, but their role in electrolyte transport in the adult lung is not known. We isolated alveolar type II cells from adult rat lung and maintained them on plastic culture dishes alone, on plastic culture dishes coated with an extracellular matrix, and on collagen-coated Millipore filters. Numerous large domes were formed on culture dishes coated with the extracellular matrix; smaller domes were formed on uncoated plastic culture dishes. Sodium butyrate (3 mM) stimulated dome formation. Transmission electron microscopy showed that the epithelial cells had flattened but still retained lamellar inclusions and that the cells were polarized with microvilli on the apical surface facing the culture medium. The electrical properties of the monolayers maintained on collagen-coated Millipore filters were tested in two laboratories. The transepithelial potential differences were 0.7 +/- 0.1 mV (24 filters, seven experiments) and 1.3 +/- 0.1 mV (13 filters, two experiments) apical side negative, and the corresponding resistances were 217 +/- 11 ohm X cm2 and 233 +/- 12 ohm X cm2. Terbutaline (10 microM) produced a biphasic response with a transient decrease and then a sustained increase in potential difference. Amiloride (0.1 mM) completely abolished the potential difference when it was added to the apical side but not when it was added to the basal side, whereas 1 mM ouabain inhibited the potential difference more effectively from the basal side. Thus, type II cells form a polarized epithelium in culture, and these cells actively transport electrolytes in vitro.
体外上皮细胞的液体和电解质转运可通过培养细胞形成穹顶的能力以及单层培养物的电特性来识别。肺泡上皮细胞被认为在胎儿肺的液体运动中起部分作用，但它们在成年肺电解质转运中的作用尚不清楚。我们从成年大鼠肺中分离出II型肺泡细胞，并将它们单独培养在塑料培养皿上、涂有细胞外基质的塑料培养皿上以及胶原包被的微孔滤膜上。在涂有细胞外基质的培养皿上形成了许多大的穹顶；在未涂覆的塑料培养皿上形成了较小的穹顶。丁酸钠（3 mM）刺激穹顶形成。透射电子显微镜显示上皮细胞已变扁平，但仍保留板层小体，并且细胞呈极化状态，顶表面朝向培养基的一侧有微绒毛。在两个实验室对维持在胶原包被的微孔滤膜上的单层细胞的电特性进行了测试。跨上皮电位差分别为0.7±0.1 mV（24个滤膜，7次实验）和1.3±0.1 mV（13个滤膜，2次实验），顶侧为负，相应的电阻分别为217±11 ohm×cm2和233±12 ohm×cm2。特布他林（10 microM）产生双相反应，电位差先短暂下降然后持续升高。氨氯地平（0.1 mM）添加到顶侧时完全消除了电位差，但添加到基底侧时则没有，而1 mM哇巴因从基底侧更有效地抑制了电位差。因此，II型细胞在培养中形成极化上皮，并且这些细胞在体外积极转运电解质。
