TRACE METAL ALTERATION OF RENAL PORPHYRIN METABOLISM

此应用程序的广泛目标是扩展过去和正在进行的 研究旨在确定基本机制， 中微量金属的卟啉生成和组织损伤特性 生物组织 该研究将集中在机制， 微量金属会导致卟啉积聚（卟啉症）和细胞损伤 （肾毒性）在哺乳动物的肾脏，一个主要的目标器官， 许多重要的有毒金属。 主要假设是 肾性卟啉症与肾毒性有共同之处 反应性氧化剂（过氧化物， 自由基）和细胞谷胱甘肽（GSH）的消耗， 在长时间的金属接触中。 这些事件促进了 减少卟啉和细胞成分的过氧化，导致 分别进展为卟啉症和细胞损伤。 建议进行研究，以确定金属（1） 耗尽细胞GSH和（2）引起反应性氧化剂的形成， 并确定这些事件如何相互作用以（3）促进卟啉病ND（4） 造成细胞损伤。 甲基汞长期暴露模型 卟啉症和细胞损伤的Sprague-Dawley大鼠肾脏发展在这个 研究这些机制的实验室将被用作主要的 实验模型 高灵敏度HPLC荧光分光光度测定 程序将用于测量肾脏中的卟啉发生事件， 馏分和定量金属对GSH代谢的影响。 反应性 肾细胞的氧化剂形成将通过建立的 分光光度法 超微结构/形态测定和 将采用酶微量测定技术来确定 GSH耗竭导致细胞成分脂质过氧化， 反应性氧化剂的形成是金属中毒时肾细胞损伤的原因 exposure. 拟议的研究将大大增加目前对 有毒微量金属改变GSH调节的机制 代谢并促进生物组织中反应性氧化剂的形成， 以及这些事件在金属诱导的卟啉症中的作用， 肾毒性 确定一种常见的机械病因， 金属的致卟啉和组织损伤特性将建立 肾性卟啉症的生物学和潜在诊断意义 作为一种中毒前表现的生化事件相关的 在肾细胞中引发金属毒性。

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.