GLUTATHIONE AND MITOCHONDRIA IN TOXIC RENAL INJURY

哺乳动物肾单位由几个细胞群组成，这些细胞群拥有 独特的生化和生理特性以及每个细胞 人群对化学毒物或病理物质的反应不同 缺氧或缺血等条件。要了解属性是什么 负责特定细胞类型对化学物质和 病理损伤，我们关注了两个显著的细胞因素， 谷胱甘肽(GSH)状态和线粒体功能。GSH是一把钥匙 细胞防御活性亲电体和氧化剂的成分， 细胞损伤的两个最常见的生产者在毒性和 疾病。肾脏与GSH的不同之处在于它拥有 包括合成能力和运输能力。特定于细胞类型的差异 对谷胱甘肽状态的调节可能在确定细胞 易受伤害。正确的线粒体功能对 为肾脏功能保持恒定的高能量输入。 因此，肾脏细胞容易受到能量供应中断的影响。 由于线粒体功能障碍。因为线粒体是经常被攻击目标 毒性或病理损伤中的部位，细胞类型特定的差异 线粒体的特性也可能有助于细胞的易感性 致伤。这些研究中提出的研究将具体集中在 谷胱甘肽跨细胞质膜和跨膜转运机制 线粒体内膜。新鲜分离的大鼠来源细胞 肾近端小管(PT)和远端小管(DT)，线粒体来源 来自肾皮质的线粒体，以及从肾PT和DT细胞纯化的线粒体 一种新的分馏技术将是所使用的生物系统。这个 分馏技术是新颖的，因为它是唯一可用的方法 从单个细胞中分离具有功能活性的线粒体 足以进行生化研究的数量。这样做的具体目的是 研究将：(L)确定谷胱甘肽跨膜转运的机制 不同肾细胞群中的质膜并探讨 这些过程在调节细胞内GSH状态中的作用；(2) 谷胱甘肽和谷胱甘肽二硫化物的作用机制 肾皮质线粒体的转运；和(3)表征 特异性肾细胞纯化线粒体的生化特性 并确定线粒体谷胱甘肽转运和 毒物差异敏感性中的能量学。通过填写 为了达到上述目的，我们将描述谷胱甘肽跨膜转运的机制。 细胞质膜和线粒体内膜，我们将 确定负责线粒体GSH运输的蛋白质，我们将 描述线粒体谷胱甘肽转运活性与 线粒体新陈代谢和细胞能量学，我们将利用这些 结果获得关于线粒体和细胞的作用的信息 肾PT和DT细胞对化学药物敏感性的异质性 病理性损伤。这些结果最终将有助于 维持或改善肾功能的程序。

The mammalian nephron is composed of several cell populations that possess distinctive biochemical and physiologic properties and each cell population responds differently to chemical toxicants or to pathologic conditions such as hypoxia or ischemia. To understand what properties are responsible for cell type-specific susceptibility to chemical and pathologic injury, we have focussed on two salient cellular factors, glutathione (GSH) status and mitochondrial function. GSH is a key component of cellular defense against reactive electrophiles and oxidants, two of the most common producers of cellular injury in both toxicity and disease. The kidney is unusual with respect to GSH in that it possesses both synthetic and transport capabilities. Cell type-specific differences in regulation of GSH status may be important in determining cellular susceptibility to injury. Proper mitochondrial function is critical to maintain a constant and high energy input for renal function. Consequently, renal cells are vulnerable to interruptions in energy supply due to mitochondrial dysfunction. Since mitochondria are frequent target sites in toxic or pathologic injury, cell type-specific differences in properties of mitochondria may also contribute to cellular susceptibility to injury. Research proposed in these studies will focus specifically on mechanisms of GSH transport across cellular plasma membranes and across mitochondrial inner membranes. Freshly isolated cells derived from rat kidney proximal tubule (PT) and distal tubule (DT), mitochondria derived from renal cortex, and mitochondria purified from renal PT and DT cells by a novel fractionation technique will be the biological systems used. The fractionation technique is novel because it is the only method available to isolate functionally viable mitochondria from single cells in quantities sufficient for biochemical studies. The specific aims of this research will be: (l) To determine the mechanism of GSH transport across plasma membranes in different renal cell populations and to investigate the role of these processes in regulation of intracellular GSH status; (2) to determine the mechanisms of GSH and glutathione disulfide (GSSG) transport in renal cortical mitochondria; and (3) to characterize biochemical properties of mitochondria purified from specific renal cell populations and to determine the role of mitochondrial GSH transport and energetics in differential susceptibility to toxicants. By completion of the above aims, we will delineate mechanisms of GSH transport across cellular plasma membranes and mitochondrial inner membranes, we will identify the protein responsible for mitochondrial GSH transport, we will describe the interaction of mitochondrial GSH transport activity with mitochondrial metabolism and cellular energetics, and we will use these results to gain information on the role of mitochondrial and cellular heterogeneity in susceptibility of renal PT and DT cells to chemical and pathologic injury. These results will ultimately help in development of procedures to maintain or improve kidney function.