CONICET | Buscador de Institutos y Recursos Humanos

The cortical, medullary and papillary regions of rat kidney were evaluated for a series of parameters related to hydrogen peroxide metabolism and oxidative stress. The rates of oxygen uptake, prostaglandin synthesis and malondialdehyde production by kidney slices were: 47, 0.003 and 0.051 μmol/h g wet wt., respectively, in cortex, 32, 0.023 and 0.035 in medulla and 22, 0.034 and 0.007 in papilla. The activities of superoxide dismutase, catalase and glutathione peroxidase were: 144 ± 16 G/g wet wt., 800 ± 100 pmol/g wet wt., and 177 ±16 U/g wet wt. in cortex; 197 ± 9 U/g wet wet., 550 ± 50 pmol/g wet wt., and 142 ± 18 U/g wet wt. in medulla; and 23 ± 2 U/g wet wt., 90 ± 9 pmol/g wet wt., and 147 ± 5 U/g wet wt. in papilla. Hydrogen peroxide steady-state concentrations were 0.09 ± 0.01, 0.07 ± 0.01 and 0.08 ± 0.01 μM whereas alpha-tocopherol content was 21 ± 2, 23 ± 1 and 34 ± 3 μmol/g wet wt. and hydroperoxide-initiated chemiluminescence was 22 ± 2, 33 ± 2 and 14 ± 1 cpm. 10−3/mg prot for cortex, medulla and papilla, respectively. After 60 min ischemia-30 min reperfusion hydroperoxide-initiated chemiluminescence and hydrogen peroxide steady-state concentration increased by 30% and 60% in cortex and 80% and 60% in medulla, whereas alpha-tocopherol content decreased by 30%, 50% and 2% in cortex, medulla and papilla, respectively. The reperfusion/control ratio of hydroperoxide-initiated chemiluminescence and hydrogen peroxide steady-state concentrations in cortex and medulla indicate the occurrence of oxidative stress after ischemia-reperfusion. The lower sensitivity to oxidative stress found in papilla could be explained by the relatively high relationship of alpha-tocopherol content to hydrogen peroxide production rate in this sub-organ.

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