title: High D-glucose-induced changes in endothelial Ca2+/EDRF signaling are due to generation of superoxide anions.
abstract: Pretreatment of porcine aortic endothelial cells with high D-glucose results in enhanced endothelium-derived relaxing factor (EDRF) formation (39%) due to increased endothelial Ca2+ release (57%) and Ca2+ entry (97%) to bradykinin. This study was designed to investigate the intracellular mechanisms by which high D-glucose affects endothelial Ca2+/EDRF response. The aldose-reductase inhibitors, sorbinil and zopolrestat, failed to diminish high D-glucose-mediated alterations in Ca2+/EDRF response, suggesting that aldose-reductase does not contribute to high D-glucose-initiated changes in Ca2+/EDRF signaling. Pretreatment of cells with the nonmetabolizing D-glucose analog, 3-O-methylglucopyranose (3-OMG), mimicked the effect of high D-glucose on Ca2+ release (41%) and Ca2+ entry (114%) to bradykinin, associated with elevated EDRF formation (26%). High D-glucose and 3-OMG increased superoxide anion (O2-) formation (133 and 293%, respectively), which was insensitive to inhibitors of cyclooxygenase (5,8,11,14-eicosatetraynoic acid [ETYA], indomethacin), lipoxygenase (ETYA, gossypol, nordihydroguaiaretic acid [NDGA]), cytochrome P450 (NDGA, econazole, miconazole), and nitric oxide (NO) synthase (L-omega N-nitroarginine), while it was diminished by desferal, a metal chelator. The gamma-glutamyl-cysteine-synthase inhibitor, buthioninesulfoximine (BSO), also increased formation of O2- by 365% and mimicked the effect of high D-glucose on Ca2+/EDRF signaling. The effects of high D-glucose, 3-OMG, and BSO were abolished by co-incubation with superoxide dismutase. Like high D-glucose, pretreatment with the O2(-)-generating system, xanthine oxidase/hypoxanthine, elevated bradykinin-stimulated Ca2+ release (+10%), Ca2+ entry (+75%), and EDRF (+73%). We suggest that prolonged exposure to pathologically high D-glucose concentration results in enhanced formation of O2-, possibly due to metal-mediated oxidation of D-glucose within the cells. This overshoot of O2- enhances agonist-stimulated Ca2+/EDRF signaling via a yet unknown mechanism.
authors.affiliation: Department of Medical Biochemistry, University of Graz, Austria. wolfgang.graier@kfunigraz.ac.at
authors.forename: W F
authors.initials: WF
authors.lastname: Graier
authors.forename: S
authors.initials: S
authors.lastname: Simecek
authors.forename: W R
authors.initials: WR
authors.lastname: Kukovetz
authors.forename: G M
authors.initials: GM
authors.lastname: Kostner
mesh_terms: D015117:5,8,11,14-Eicosatetraynoic Acid / Q000494:pharmacology; D000818:Animals; D001011:Aorta; D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000378:metabolism; D003571:Cytochalasin B / Q000494:pharmacology; D003676:Deferoxamine / Q000494:pharmacology; D004464:Econazole / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000494:pharmacology*; D006072:Gossypol / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D048289:Imidazolidines; D007213:Indomethacin / Q000494:pharmacology; D007700:Kinetics; D009637:Masoprocol / Q000494:pharmacology; D008825:Miconazole / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D013481:Superoxides / Q000378:metabolism*; D013552:Swine; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; D007093:Imidazoles; D048289:Imidazolidines; D013481:Superoxides; D015117:5,8,11,14-Eicosatetraynoic Acid; D009569:Nitric Oxide; D003571:Cytochalasin B; D004464:Econazole; D009637:Masoprocol; D008825:Miconazole; D019001:Nitric Oxide Synthase; C026411:sorbinil; D006152:Cyclic GMP; D005947:Glucose; D003676:Deferoxamine; D006072:Gossypol; D001920:Bradykinin; D002118:Calcium; D007213:Indomethacin