MACROMOLECULAR TRANSPORT ACROSS LUNG ALVEOLAR EPITHELIUM

拟议研究的具体目标是调查 大分子跨膜转运的特点及调控 肺上皮屏障正常和异常。我们将研究两个 分离的肺泡上皮，即中空两栖动物的制备 肺和大鼠肺II型细胞单层。这些准备工作将是 用于研究大分子的传输特性并确定 大分子跨肺泡转运的途径和机制 上皮组织。牛蛙的肺将作为平板安装在 哺乳动物的Ussing型膜室或悬浮囊和单层 肺II型细胞将在多孔性表面生长，随后 研究了它们的大分子传输特性。单向 放射性示踪剂通量测量及表观渗透率分析 属性将被执行。大分子的特殊途径 将通过研究一些可能的机制来研究运输 详细地说。我们将调查由于以下原因可能导致的蛋白质碎裂 跨上皮电对肺泡上皮细胞消化的影响 梯度、饱和度、竞争(抑制)和刺激 大分子通量。为了验证大分子的假设 是通过囊泡途径运输的，我们将研究 大分子的吸附和内化，以及 囊泡转运抑制剂。电荷密度的影响将是 利用阳离子、中性和阴离子大分子进行了研究。 蛋白质(与聚阳离子)偶联的可能刺激效应 也将被确定。大分子转运的非特异性效应 关于小溶质和水通量的研究将进一步确定 大体积内吞途径在肺泡上皮中的作用。我们会 研究代谢抑制剂、温度、pH、肺的影响 伤害，以及外源性和内源性物质对大分子运输的影响 肺泡上皮细胞的特性。期待我们的学习 将提供有关以下方面的信息： 大分子转运通过肺泡上皮屏障，并将 帮助阐明哺乳动物肺泡上皮运输特性 病理生理条件及其在预防、形成、 体内肺泡性肺水肿的消退。

The specific objectives of the proposed studies are to investigate the characteristics and regulation of macromolecular transport across the normal and abnormal pulmonary epithelial barrier. We will study two preparations of isolated alveolar epithelium, namely, hollow amphibian lungs and rat lung type II cell monolayers. These preparations will be utilized to study macromolecular transport properties and determine pathways and mechanisms for macromolecule translocation across the alveolar epithelium. Bullfrog lungs will be studied as flat sheets mounted in Ussing-type flux chambers or as suspended sacs, and monolayers of mammalian lung type II cells will be grown on porous surfaces and subsequently studied for their macromolecular transport characteristics. Unidirectional radiotracer flux measurements and analysis of apparent permeability properties will be performed. Specific pathways of macromolecular transport will be investigated by studying a number of potential mechanisms in detail. We will investigate possible fragmentation of proteins due to digestion by the alveolar epithelium, effects of transepithelial electrical gradients, saturation, competition (inhibition) and stimulation of macromolecular fluxes. In order to test the hypothesis that macramolecules are transported via vesicular pathways, we will study the kinetics of adsorption and internalization of macromolecules, as well as the effects of vesicular transport inhibitors. The influence of charge density will be investigated utilizing cationic, neutral, and anionic macromolecules. Possible stimulatory effects of conjugation of proteins (with polycations) will also be determined. Non-specific effects of macromolecular transport on small solute and water fluxes will be studied to further determine the role of a bulk endocytotic pathway in the alveolar epithelium. We will investigate the effects of metabolic inhibitors, temperature, pH, lung injury, and exogenous and endogenous substances on macromolecular transport properties of the alveolar epithelium. It is expected that our studies will provide information on the characteristics and regulation of macromolecular transport across the alveolar epithelial barrier, and will help elucidate mammalian alveolar epithelial transport properties in pathophysiological conditions and their roles in the prevention, formation, and resolution of alveolar pulmonary edema in vivo.