Effect of uranyl nitrate on enzymes of carbohydrate metabolism and brush border membrane in different kidney tissues

Uranium, the heaviest of the naturally occurring elements is widely present as environmental contaminant from natural deposits, industrial emissions and most importantly from modern weapons. Histopathological examinations revealed that uranyl nitrate (UN) exposure caused severe damage to pars recta of renal proximal tubule. However, biochemical events involved in cellular response to renal injury are not completely elucidated. We hypothesized that UN exposure would severely damage kidney tissues and alter their metabolic functions. Rats were treated with a single nephrotoxic dose of UN (0.5 mg/kg body weight) i.p. After 5 d, effect of UN was studied on the activities of various enzymes of carbohydrate metabolism, brush border membrane (BBM) and oxidative stress in different kidney tissues. Activity of lactate dehydrogenase increased whereas activities of isocitrate, succinate and malate dehydrogenases, glucose-6-phosphatase and fructose-1,6-bisphosphatase significantly decreased by UN exposure. Activity of glucose-6-phosphate dehydrogenase decreased whereas that of NADP-malic enzyme increased. The activities of BBM enzymes were significantly lowered and after dissociation from BBM excreted in urine. Lipid peroxidation and the activities of superoxide dismutase and glutathione peroxidase increased whereas catalase activity decreased by UN. UN treatment caused specific alterations in the activities of metabolic and membrane enzymes and perturbed antioxidant defenses.