ROLE OF ALTERED MEMBRANE FUNCTION IN XENOBIOTIC TOXICITY

近年来，我们研究了肾脏的机制和能量学。 有机阴离子(OA)和阳离子(OC)转运。这些是主要的 管理消除外来化学品的制度。办公自动化运输 被证明通过Na/α-与代谢能量间接偶联。 酮戊二酸(AlphaKG)共转运和OA/AlphaKG交换。我们是 目前同时检测质膜和细胞内事件 与分泌运输有关，并启动了对 这些系统的分子生物学。这项工作表明， 可以通过操作来调制，该操作改变 内部αKG浓度或其输入到输出的梯度。此外, 成像研究表明，细胞内的隔离 囊泡明显降低了细胞质中的OA浓度 在分泌过程中保护细胞内的部位。美国国税局的封存是 既有载体介导，又有能量依赖性。OC也被隔离， 这表明泡囊包装可能是一种保护 在分泌过程中运输上皮细胞。卵巢癌的发生机制 封存是一种二次活跃的质子/有机碳交换，由 质子-ATPase存在于这些内体小泡中。初步证据 表明这些小泡在心尖部的基侧方向上移动， 增加了他们也可能在 分泌的外源物质的跨细胞运动。表达克隆 目前正在使用技术来鉴定和克隆特定的膜 分泌过程中负责单个运输步骤的蛋白质 外来阴离子和阳离子。最后，细胞培养技术已经被 应用于开发用于分析的完整上皮片制剂 这些运输系统，它们的控制机制，以及它们的敏感性 对外来生物的毒性。这些研究首次表明 一条肾线(OK细胞)显示了OA的分泌和 与原代培养的大鼠近端小管相比，它们提供了一种 分析Oa和Oc跨上皮转运控制的方法 完整的上皮组织。

In recent years, we have examined the mechanism and energetics of renal organic anion (OA) and cation (OC) transport. These are the primary systems which govern the elimination of foreign chemicals. OA transport was shown to be indirectly coupled to metabolic energy through Na/alpha- ketoglutarate (alphaKG) co-transport and OA/alphaKG exhange. We are currently examinng both plasma membrane and intracellular events associated with secretory transport and initiating studies of the molecular biology of these systems. This work indicates that the rate of OA transport may be modulated by manipulations which alter either the internal alphaKG concentration or its in-to-out gradient. In addition, imaging studies indicate that sequestration within intracellular vesicles reduces the cytoplasmic OA concentrations, apparently protecting intracellular sites during secretion. Sequestration of OA is both carrier mediated and energy dependent. OC are also sequestered, suggesting that vesicular packaging may be a general means of protecting transporting epithelial cells during secretion. The mechanism of OC sequestration was a secondary active proton/OC exchange, driven by a proton-ATPase present in these endosomal vesicles. Initial evidence indicates that these vesicles move in a basolateral to apical direction, raising the possibility that they may also play a direct role in transcellular movement of secreted xenobiotics. Expression cloning techniques are currently in use to identify and clone specific membrane proteins responsible for individual transport steps in secretion of foreign anions and cations. Finally, cell culture techniques have been applied to develop intact epithelial sheet preparations for analysis of these transport systems, their control mechanisms, and their sensitivity to xenobiotic toxicity. These studies have shown for the first time that a renal line (the OK cell) demonstrates OA secretion and in comparison with primary cultures of rat proximal tubule, they provide a means to analyze control of transepithelial OA and OC transport in intact epithelial.