Oxidative stress in endotoxemic rats assesed as the ratio ascorbyl radical/ascorbate content in plasma

GALLEANO MONICA; CARDOSO NANCY; AIMO LUCILA; PUNTARULO SUSANA

Buenos Aires,

Congreso; 12th Biennial Meeting International Society for Free Radical Research; 2004

International Society for Free Radical Research

The aim of this work was to evaluate oxidative stress in a model of endotoxemia employing the ratio ascorbyl radical/ascorbate content (A· /AH-) in rat plasma. Female Sprague-Dawley rats were administered with lipopolysaccharide from Escherichia coli (serotype 0127:B8) (ip 4 mg/kg) (LPS) and samples were obtained after 0 h, 1.5 h, 3 h and 6 h of the treatment. Nitric oxide production was followed by measuring NO-Hb in blood by EPR and showed a significant increase starting 3 h after LPS administration. Carbonyl groups content in plasma proteins were increased significantly over the same period (+28%), while plasma TBARS and the content of thiol groups were unaffected by the treatment. Total iron content in plasma decreased significantly after 6 h of LPS administration (30±5 mM and 13±3 mM for controls and 6 h-treated rats, respectively). Plasma A· was measured by EPR at room temperature and plasma AH- was detected by reverse phase HPLC. The ratio A· /AH- was significantly higher in endotoxemic rats ([6.0±0.5]x10-4 and [10.4±0.9]x10-4 for control and 6 h-treated rats respectively). These data suggest that the ratio A· /AH- is an early and sensitive indicator of oxidative stress in this experimental model, however modifications in the content of catalytically active iron in plasma should be further study to asses iron role under these conditions. Supported by University of Buenos Aires, ANPYCT and CONICET.