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O. Zeitz, L. Schlichting, G. Richard, O. Strauss; Potentiation of Oxidative Damage in Cultured RPE Cells by Vitamin C and Pyruvate . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1628.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose:Antioxidants have been postulated in the AREDS–trial to have beneficial effect on progression of AMD. The present study investigates the potential of vitamin C and pyruvate to protect the retinal pigmentepithelium (RPE ) against the cell death induced by free radicals. Methods:1) Radicals were generated by the Fenton reaction from H2O2 under catalysis of Fe3+. 2) Anti–oxidative properties were examined in absence of living cells or tissue using the Dihydrorhodamine[DHR]–Assay which is specific for hydroxyl radicals (MoBiTec, Germany). 3) ARPE–19 cell culture was exposed in a self designed set–up to hydroxyl radicals. Cell survival rate was determined by the life–dead–assay provided by MoBiTec (Germany). Results: Without addition of any scavengers the DHR–Assay exhibited an increase in average fluorescence to 8.8±0.1 (n=4) relative Light–units (LU) after initiating the Fenton reaction. Vitamin C was able to reduce this increase in a concentration dependent manner to 1.0±0.0 LU at 1 mM vitamin C (n=4), pyruvate to 1.2±0.1 LU at 3 mM (n=4). In RPE cell culture, 6 minutes exposure to hydroxyl radicals lead to a loss of living cells by 4.9±2.7% (n=6). In presence of 1 mM pyruvate 16.0±3.0% (n=6) and in presence of vitamin C 23.3±2.9 % (n=6) of the cells did not survive the radical treatment. Conclusions: Vitamin C and pyruvate scavenge hydroxyl radicals in the DHR–Assay, whereby vitamin C appears to be little more effective than pyruvate. In sharp contrast, both compounds failed to protect RPE–cells, but oxidative damage is potentiated in presence of pyruvate or vitamin C. This observation demonstrates that antioxidative treatment needs to be carefully adjusted to the target tissue.
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