GLUTATHIONE AND MITOCHONDRIA IN TOXIC RENAL INJURY

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Glutathione and mitochondrial functions play important roles in protecting cells from injury and in maintenance of cellular homeostasis. The kidneys are susceptible to injury from many toxic chemicals and pathological states. All segments of the nephron, however, are not equally sensitive to injury. The principal objective of this research is to characterize the disposition and role of glutathione in renal mitochondrial and to study the influence of glutathione status and mitochondrial function in renal injury. Isolated mitochondria and purified or highly enriched cell suspensions of individual segments of the nephron from male Fischer 344 rats will be used. Because of their predominance and, therefore, ease of isolation, initial studies will be conducted with proximal tubular cells and renal cortical mitochondria. The specific questions addressed are: 1) What is the origin of renal mitochondrial glutathione and how is its disposition regulated? 2) What is the role of glutathione in renal proximal tubular mitochondrial function? 3) What role do glutathione status and mitochondrial function play in the susceptibility of renal proximal tubular cells to chemical injury? 4) Can procedures be developed to isolate highly enriched populations of thick ascending limb, distal tubular, and cortical collecting tubular cells, and how do their biochemical properties and susceptibility to injury compare to those of proximal tubular cells? Percoll density-gradient centrifugation will be used in cell purification. Digitonin fractionation of isolated cells will be used to separate cytosol and mitochondria, enabling more direct study of mitochondrial function. Agents that selectively alter glutathione concentrations and redox status and those that alter mitochondrial bioenergetics will be employed to explore the role of glutathione in mitochondrial function. Chemical injury will be induced by the use of various toxic chemicals, and the role of glutathione and mitochondrial oxidative activity in protection from and sensitivity to injury will be hydroperoxide, methyl vinyl ketone, S-(2- chloroethyl)-DL-cysteine) and compounds requiring metabolic activation (the analgesic acetaminophen, the antibiotic cephaloridine, the base status on cellular susceptibility to injury will also be investigated. The research will help provide a better understanding of renal drug metabolism and the biochemical mechanisms by which chemicals produce nephrotoxicity.