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L. Xu, W. Wu, J. S. Penn, F. M. Recchia; Ascorbate and Health Maintenance in Cultured Rat Retinal Endothelial Cells. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2959.
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The antioxidant ascorbate may help to regulate expression of hypoxia-inducible factor 1-alpha (Hif 1-) through its role as a cofactor for the modulating enzyme prolyl hydroxylase. While it is known that ascorbate is much more abundant in vitreous fluid than in plasma, its potential role in maintaining retinal health is unclear. The purpose of this study was to describe the effect of ascorbate on the growth and phenotype of rat retinal microvascular endothelial cells (RMECs).
Primary cultures of RMECs were grown under either normoxia or hypoxia (< 5% O2) and treated with varying concentrations (0 to 250 µM) of ascorbate. Endothelial cells were confirmed by staining with the endothelial specific marker GS-IB4. Endothelial cell density was measured, and cell morphology was examined. Immunocytochemistry was performed to localize Hif1 within RMECs.
Ascorbate preserved RMEC cell density in a dose-dependent manner following exposure to hypoxia. For example, RMEC density following treatment with 250 µM was twice that of untreated cells. Both normal and abnormal morphologies of GS-IB4-positive rat RMECs were seen following hypoxic treatment. In normal rat RMECs, Hif1 and degradation products were found in the cytoplasm, while in abnormal rat RMECs, Hif1 appeared to accumulate in the nucleus. Treatment with 250 µM ascorbate decreased the number of abnormal-appearing cells by over 50%.
These results suggest that ascorbate may play a role in maintaining health and attenuating the stress response to hypoxia in rat retinal microvascular cells.
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