172 - Ascorbic acid increases cell death in fibroblast and VERO cultures after oxidative and thermic stress

L. Zanatta, M. Sandri, P. Arslan. Background: Ascorbic acid has been considered to act as a scavenger of free radicals generated in the cell after oxidative stress. Cultured rat fibroblasts and monkey kidney tumor cells (cell line VERO) were subjected to oxidative and thermic stress in the presence and absence of ascorbic acid in order to directly test this action. Materials and Methods: The cell viability was analyzed by a cell proliferation assay (XTT), while cell death was studied by in situ DNA nick/end labeling (TUNEL), double vital Hoechst/Propidium iodide staining and nuclear morphology. Results: The incubation of the cells with hydrogen peroxide for different times showed that after 2 hours the majority of the cells were dead and ascorbic acid did not protect fibroblast and VERO cells from this oxidative stress. The decrease of cell viability is dependent on hydrogen peroxide concentration and is not affected by the presence of increasing concentrations of ascorbic acid. Necrotic cell death occurs after a loss of cell membrane integrity without nuclear shrinking and lack of labeling by TUNEL. Similar results were obtained after inducing a thermic stress. Conclusions: Under the present experimental conditions ascorbic acid did not protect the cells but rather increased the effects of both the oxidative and the thermic stress.