TRACE METAL ALTERATION OF RENAL PORPHYRIN METABOLISM

该应用程序总体目标是扩展过去的和正在进行的 研究的目的是定义构成 土壤中痕量金属的致卟性和组织损伤特性 生物组织。这项研究将集中在通过什么机制 微量金属引起卟啉蓄积(卟啉中毒)和细胞损伤 (肾毒性)在哺乳动物肾脏，一个主要的靶器官 大量具有毒理意义的金属。主要假设是 被检测的是肾卟啉症和肾毒性有一个共同之处 反应性氧化剂(过氧物， 自由基)和细胞内谷胱甘肽(GSH)的耗竭 在长时间的金属暴露中。这些事件促进了氧化 减少的卟啉和细胞成分的过氧化，导致 进行性分别发展为卟啉症和细胞损伤。 有人建议进行研究，以确定金属(1) 耗尽细胞GSH和(2)引发活性氧化剂的形成， 并确定这些事件如何相互作用(3)促进卟啉中毒(4) 造成细胞损伤。甲基汞长期染毒模型的建立 SD-Dawley大鼠肾脏的卟啉症和细胞损伤 这些机制的研究实验室将作为主要实验室 实验模型。高灵敏高效液相色谱-荧光分光光度分析 程序将被用来测量肾脏中产生卟啉的事件 并量化金属对谷胱甘肽代谢的影响。反应性 肾细胞氧化剂的形成将通过建立 分光光度程序。超微结构/形态计量学 将采用酶促微量测定技术来确定是否 谷胱甘肽耗竭引起的细胞成分的脂质过氧化 反应性氧化剂的形成是金属过程中肾细胞损伤的原因之一 曝光。 这项拟议的研究将大大增加目前对 有毒痕量金属改变谷胱甘肽调节的机制 代谢和促进生物组织中活性氧化剂的形成， 以及这些事件在金属诱导的卟啉症和 肾毒性。一种常见的骨质疏松症发病机制的鉴定 金属的产卟啉和组织损伤特性将被确立 肾卟啉症的生物学及潜在诊断意义 作为中毒前的表现，生化事件与 肾细胞中金属毒性的启动。

The broad objective of this application is to extend past and ongoing research aimed at defining the basic mechanisms which underlie the porphyrinogenic and tissue damaging properties of trace metals in biological tissues. The research will focus on the mechanisms by which trace metals cause porphyrin accumulation (porphyria) and cell injury (nephrotoxicity) in mammalian kidney, a principal target organ of numerous metals of toxicologic importance. The principal hypothesis to be tested is that renal porphyria and nephrotoxicity have a common mechanistic etiology in the formation of reactive oxidants (peroxides, free radicals) and depletion of cellular glutathione (GSH) which occur during prolonged metal exposures. These events promote oxidation of reduced porphyrins and peroxidation of cellular constituents, leading progressively to porphyria and cell injury, respectively. Studies are proposed to define the precise mechanisms by which metals (1) deplete cellular GSH and (2) elicit the formation of reactive oxidants, and to identify how these events interact to (3) promote porphyria nd (4) cause cell injury. A prolonged-exposure model of methyl mercury-induced porphyria and cell injury in Sprague-Dawley rat kidney developed in this laboratory for study of these mechanisms will be used as the principal experimental model. Highly sensitive HPLC-spectrofluorometric assay procedures will be used to measure porphyrinogenic events in kidney fractions and to quantitate metal effects on GSH metabolism. Reactive oxidant formation by renal cells will be measured by established spectrophotometric procedures. Ultrastructural/morphometric and enzymatic microdetermination techniques will be employed to determine if lipid peroxidation of cell constituents resulting from GSH depletion and reactive oxidant formation is a cause of renal cell injury during metal exposure. The proposed research will add substantially to current understanding of the mechanisms by which toxic trace metals alter the regulation of GSH metabolism and promote reactive oxidant formation i biological tissues, and the role of these events in metal-induced porphyria and nephrotoxicity. Identification of a common mechanistic etiology of the porphyrinogenic and tissue damaging properties of metals will establish the biological and potential diagnostic significance of renal porphyria as a pre-toxic manifestation of biochemical events associated with the initiation of metal toxicity in kidney cells.