Abstract 14604: Partial Mitochondrial Depolarization and Mitochondrial Antioxidant Treatment Reverse Low Glucose Induced Endothelial Dysfunction in Human Arterioles
Introduction: Clinically relevant low glucose (LG) exposure (40-70 mg/dL) rapidly induces a loss of nitric oxide (NO) bioavailability with concomitant mitochondrial hyperpolarization and excessive mitochondrial superoxide (O2-) production in cultured human endothelial cells. LG also impairs vasodilation to acetylcholine (Ach) in intact human arterioles. Whether mitochondrial targeted therapies reverse LG-induced endothelial dysfunction in intact human vessels remains unknown.
Methods: Human arterioles (~100 µm) were obtained by subcutaneous gluteal adipose biopsy or from discarded subcutaneous adipose from surgery. Vessels were exposed to normal glucose (NG, 90 mg/dL) or low glucose (LG,50 mg/dL) buffer for 30 minutes. Vasodilation to Ach (10-10- 10-5 M) was determined with and without exposure to the mitochondrial specific antioxidant, mitoTEMPOL (1 mM), or the mitochondrial uncoupling agent, CCCP (100 nM). NO related endothelium-independent vasodilation under NG and LG condition was determined by exposing vessels to NONOate (10-10- 10-5 M). NO bioavailability and mitochondrial O2- production under NG and LG condition with and without exposure to CCCP were measured by diaminofluorescein diacetate (DAF2-DA) and MitoSox™ fluorescence, respectively.
Results: MitoTEMPOL (n = 3, p<0.001) and CCCP (n=3, p<0.001) completely reversed LG-induced impaired endothelial dependent vasodilation to acetylcholine. LG induced reductions in NO bioavailability in these vessels was reversed by CCCP (n=5, p=0.02 overall, P<0.05 for LG vs. NG, NG+CCCP, and LG+CCCP). CCCP also reduced mitochondrial O2- levels (n=3, P=0.002 overall, P<0.05 for LG vs. NG,NG+CCCP, and LG+CCCP) in these arterioles. LG had no effect on vasodilation to NONOate (n=3, p=NS).
Conclusion: Pathological mitochondrial hyperpolarization and excessive mitochondrial O2- production are mechanistically related to LG induced endothelial dysfunction and losses of NO bioavailability in human arterioles. Treatment with either low dose mitochondrial uncoupling agents or mitochondrial specific antioxidants reverses these effects. These data suggest new targets for blunting the adverse effects of hypoglycemia exposure on endothelial function.
- © 2012 by American Heart Association, Inc.