Abstract
BackgroundType 2 diabetes mellitus (DM2) remains an increasing cause of morbidity and mortality in the Western world, including coronary artery disease and myocardial infarction. In order to eventually test mechanisms of cardioprotection by different agents, we sought to develop an in‐vitro model of mouse DM2 coronary artery endothelial cells (ECs) undergoing hypoxia/reoxygenation (HR) injury under normal and high glucose concentrations. We hypothesized that high glucose exacerbates HR injury.MethodsDM2‐ECs, grown to confluency in complete media (5% fetal bovine serum and 5.5 mM glucose), were exposed to normal (5.5 mM) or high (20.5 mM) glucose concentrations for 72 hrs. They were then were subjected to normoxic (21% O2, complete media) or hypoxic (0.0125% O2, FBS‐ and glucose‐free media) conditions for 8 hrs, followed by reoxygenation in complete media for 16 hrs. To assess the extent of injury, cell (CyQUANT GR dye) and mitochondrial viability (3‐(4,5‐dimethylthiazol‐2‐yl)‐5‐(3‐carboxymethoxyphenyl)‐2‐(4‐sulfophenyl)‐2H‐tetrazolium; MTS) as well as cellular injury (lactate dehydrogenase release; LDH) were measured. Statistics: Two‐Way ANOVA followed by Tukey post‐hoc testing; alpha = 0.05 (two‐tailed).ResultsUnder both normal and high glucose conditions, HR caused a significant decrease in cell number and increase in LDH release, while MTS remained unchanged. The injury by HR under high compared to under normal glucose conditions, was not different at either outcome parameter.ConclusionsIn contrast to our hypothesis, 20.5 mM glucose did not significantly exacerbate HR‐induced cellular or mitochondrial injury and also did not lead to significantly increased injury under normoxic conditions. It is conceivable that the DM2‐ECs in our in‐vitro model perceive a concentration of 20.5 mM as closer to normal and a concentration of 5.5 mM lower than normal than would be anticipated in‐vivo. Another explanation could be that the hypoxia we chose (0.0125% O2 for 8 hrs) was not strong and/or long enough to cause a significant enough damage to be exacerbated by an additional stressor. We also did not control for differences in osmolarity between normal and high glucose experiments that might have skewed our results. More research under different conditions will be necessary to elucidate the interplay of high glucose and HR injury in DM2.Support or Funding InformationThis work was supported, in part, by institutional funds; by a Merit Review Award (I01 BX003482) from the U.S. Department of Veterans Affairs Biomedical Laboratory R&D Service; by the American Heart Association’s PAECER Program (1R25HL145330); and by the National Institute of General Medical Sciences of the National Institutes of Health (R25GM113740).
Published Version
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