High Glucose Affects Mitochondrial Metabolic Capacity and Extracellular Acidification in Retinal Endothelial Cells
Abstract Number: 1006-P
Authors: KYLE TRUDEAU, ANTHONY MOLINA, SAYON ROY
Institutions: Boston, MA
Results: Mitochondrial dysfunction plays a significant role in diabetic microvascular complications; however it is unknown if high glucose (HG) affects mitochondrial metabolic capacity in retinal endothelial cells, and whether cells enact any compensating mechanism. To investigate HG effects on mitochondrial metabolic capacity in rat retinal endothelial cells (RRECs), we assessed cellular oxygen consumption, mitochondrial membrane potential (MMP), extracellular acidification, and mitochondrial content.
To assess HG-induced changes in mitochondrial metabolic capacity, RRECs grown for 3 and 6 days in normal or HG conditions were measured for rates of oxygen consumption and extracellular acidification using XF24 Extracellular Flux Analyzer. Changes in MMP were analyzed in cells grown for 6 days in normal or HG using differential staining and imaged live using confocal microscopy. To assess mitochondrial content of RRECs grown in normal or HG medium for 6 days, whole cell extract was assessed for VDAC1 expression by Western Blot.
After 3 days of HG exposure RRECs showed no significant change in steady state oxygen consumption but prolonged HG exposure of 6 days resulted in a significant decrease (1.55 vs 1.99 nmol O2/min/106 cells, p=0.016).
Maximal oxygen consumption, measured by sequential injection of oligomycin and FCCP, did not show significant reduction after 3 days of HG but was significantly reduced after 6 days of HG exposure (121±19% of baseline rate vs 168±33%, p=0.025). After 6 days of HG significant decrease in MMP was observed (74±23% of control, p=0.01). RRECs grown for 3 days in HG showed no change in extracellular acidification but displayed significant increase after 6 days of HG (135±12% of control, p=0.005). HG exposure of 6 days did not result in change of VDAC1 expression.
The findings suggest that in RRECs, HG decreases mitochondrial metabolic capacity without altering its content. Retinal endothelial cells may compensate for decreased mitochondrial metabolic capacity by possibly increasing glycolysis as indicated by increased extracellular acidification. The results may be helpful for understanding mitochondrial dysfunction in diabetic retinopathy.