Ascorbate reverses high glucose- and RAGE-induced leak of the endothelial permeability barrier

• Published in: Biochemical and biophysical research communications Vol. 445; no. 1; pp. 30 - 35
• Main Authors: Meredith, M. Elizabeth, Qu, Zhi-Chao, May, James M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 28-02-2014
• Subjects: Acetylcysteine - pharmacology; Animals; Antioxidants - pharmacology; Ascorbate; Ascorbic Acid - metabolism; Ascorbic Acid - pharmacology; Benzamides - pharmacology; Cell Line; Cell Membrane Permeability - drug effects; Cells, Cultured; Chromans - pharmacology; Cyclic N-Oxides - pharmacology; Dithiothreitol - pharmacology; Dose-Response Relationship, Drug; Endothelial Cells - drug effects; Endothelial Cells - metabolism; Endothelial permeability; Glucose - metabolism; Glucose - pharmacology; Glycation End Products, Advanced - pharmacology; High glucose; HMGB1 Protein - pharmacology; Human Umbilical Vein Endothelial Cells - drug effects; Human Umbilical Vein Endothelial Cells - metabolism; Humans; Mice; Oxidative stress; RAGE; Receptor for Advanced Glycation End Products; Receptors, Immunologic - agonists; Receptors, Immunologic - antagonists & inhibitors; Receptors, Immunologic - metabolism; Serum Albumin, Bovine - pharmacology; Spin Labels; KRH; NAC; Oxidative stress; FPS-ZM1; Hepes; SVCT2; Ascorbate; HMGB1; RAGE; Endothelial permeability; AGE; High glucose
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2014.01.078

•Endothelial cells accumulate millimolar concentrations of ascorbate after one hour.•Ascorbate decreases permeability under basal and high glucose conditions.•Glucose-induced permeability is primarily due to RAGE activation.•Ascorbate reverses the increase in permeability due to RAGE activation.•Other antioxidants are able to decrease permeability under high glucose conditions.
High glucose concentrations due to diabetes increase leakage of plasma constituents across the endothelial permeability barrier. We sought to determine whether vitamin C, or ascorbic acid (ascorbate), could reverse such high glucose-induced increases in endothelial barrier permeability. Human umbilical vein endothelial cells and two brain endothelial cell lines cultured at 25mM glucose showed increases in endothelial barrier permeability to radiolabeled inulin compared to cells cultured at 5mM glucose. Acute loading of the cells for 30–60min with ascorbate before the permeability assay prevented the high glucose-induced increase in permeability and decreased basal permeability at 5mM glucose. High glucose-induced barrier leakage was mediated largely by activation of the receptor for advanced glycation end products (RAGE), since it was prevented by RAGE blockade and mimicked by RAGE ligands. Intracellular ascorbate completely prevented RAGE ligand-induced increases in barrier permeability. The high glucose-induced increase in endothelial barrier permeability was also acutely decreased by several cell-penetrant antioxidants, suggesting that at least part of the ascorbate effect could be due to its ability to act as an antioxidant.