Abstract 410: Mitochondrial Uncoupling with CCCP Reverses Acute Hyperglycemia Induced Endothelial Dysfunction in Human Arterioles

Abstract

Background : Acute hyperglycemia (HG) impairs endothelial function, which may be related to hyperpolarization of the inner mitochondrial membrane and excessive production of mitochondrial superoxide (ROS). Mitochondrial uncoupling agents could potentially reverse endothelial dysfunction due to HG in intact human arterioles. Methods : Human adipose arterioles were incubated in either euglycemic (NG, 5mM) or hyperglycemic (HG, 33mM) buffer for 4 hours. Vessels were then exposed to increasing doses of acetylcholine (ACh) in the presence and absence of NADPH oxidase inhibitor gp91ds-tat or CCCP, (100 nM), a mitochondrial membrane uncoupling agent. Vascular superoxide levels were also measured after incubation with NG and HG using a chemiluminescent probe (L-012) in the absence and presence of 1 and 2 above. Results : ACh-induced vasodilation was impaired by HG vs. NG control (P<0.001). This impairment was modestly reversed by gp91 ds-tat (P< 0.001), but endothelial function was completely restored to the level observed under euglycemic conditions by CCCP (P=0.008 vs. HG, P>0.90 vs. NG). Endothelium-dependent vasodilation in HG vessels was greater after CCCP compared to gp91ds-tat (P<0.001). L-NAME inhibited all dilation to ACh indicating endothelium-dependence (data not shown). HG induced an increase in superoxide relative to NG (P<0.001), which was similarly suppressed by gp91ds-tat (P = 0.001) and CCCP (P=0.002). Conclusion : HG-induced endothelial dysfunction is reversed with partial uncoupling of mitochondrial oxidative phosphorylation. Mitochondrial uncoupling more than NADPH oxidase blockade improves endothelial dysfunction due to HG.