RW3 Hyperglycaemia induces reversible changes to metabolism and cell function in cultured endothelial cells: implications for the link between diabetes and cardiovascular disease

Cardiovascular disease (CVD) is the primary cause of morbidity and mortality in patients with diabetes. Endothelial cell dysfunction is a factor in the atherosclerotic process that underpins CVD, but the link between diabetes and endothelial dysfunction is not fully understood. In this study, the effects of glucose exposure on a human-derived endothelial cell line, EA.Hy926, was examined. EA.hy926 cells were grown in two distinctive pre-treatment glucose conditions during the cell growth phase: 5.5 mM (‘normal glucose’; NG) or 25 mM glucose (‘high glucose’; HG). Cells were subsequently exposed to three different test glucose concentrations for 48 hours (5.5, 12.5 and 25 mM). The effect of the glucose exposure on cell viability, growth rate, metabolism, and cell functionality were assessed. The study showed that the glucose exposure in the growth phase (HG and NG conditions) does not affect EA.hy926 cell viability, membrane integrity or growth rate. However, EA.hy926 metabolism and mitochondrial activity were modulated by the glucose concentration in the growth phase; cells cultured in NG medium showed a more energetic profile, a greater NAD/NADH ratio and ADP/ATP ratio. Increasing the test glucose concentration was also found to reduce endothelial nitric oxide (NO) synthase-derived NO generation from NG cells, as indicated by an increase in the surrogate NO marker, nitrite, in the supernatant. In conclusion, the present study found that exposure of EA.hy926 endothelial cells to hyperglycaemic conditions induced a rapid, reversible change in metabolism. In addition, acute exposure of cells to hyperglycaemic conditions had a substantial impact on mediators that are key to endothelial modulation of vascular tone and the atherosclerotic process. The results lend weight to the hypothesis that modulation of endothelial cell metabolism and function by glucose mediates the dysfunction that underpins atherogenesis.