Cytosolic Ca2+ movements of endothelial cells exposed to reactive oxygen intermediates: Role of hydroxyl radical‐mediated redox alteration of cell‐membrane Ca2+ channels

• Published in: British journal of pharmacology Vol. 126; no. 6; pp. 1462 - 1470
• Main Authors: Az‐ma, Toshiharu, Saeki, Noboru, Yuge, Osafumi
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.03.1999; Nature Publishing
• Subjects: Animals; anion channel; Aorta; Biological and medical sciences; Blood vessels and receptors; Calcium - metabolism; calcium channel; Calcium Channel Blockers - pharmacology; Calcium Channels - drug effects; Calcium Channels - metabolism; Cell Membrane - drug effects; Cell Membrane - metabolism; Cell Respiration - drug effects; Cells, Cultured; Cyclic N-Oxides - pharmacology; Cytosol - chemistry; cytotoxicity; Dithiothreitol - pharmacology; Endothelial cells; Endothelium, Vascular - cytology; Endothelium, Vascular - metabolism; Free Radical Scavengers - pharmacology; Fundamental and applied biological sciences. Psychology; Haber‐Weiss cycle; hydrogen peroxide; Hydrogen Peroxide - pharmacology; hydroxyl radical; Hydroxyl Radical - pharmacology; intracellular calcium concentration; Iron Chelating Agents - pharmacology; Nickel - pharmacology; Oxidants - pharmacology; Oxidation-Reduction - drug effects; Phenanthrolines - pharmacology; Reactive Oxygen Species - physiology; superoxide anion; Swine; Vertebrates: cardiovascular system; Xanthine - pharmacology; xanthine oxidase; Xanthine Oxidase - pharmacology; Oxidative stress; Endothelial cell; Oxygen; Enzyme; Cytotoxicity; Ionic channel; In vitro; Free radical; Pig; Vertebrata; Mammalia; Calcium ion; Blood vessel; Animal; Xanthine oxidase; Circulatory system; Artiodactyla; Oxidoreductases; Intracellular; Ungulata; Hydroxyl; Cell respiration
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1038/sj.bjp.0702438

The mode of action of reactive oxygen intermediates in cysosolic Ca2+ movements of cultured porcine aortic endothelial cells exposed to xanthine/xanthine oxidase (X/XO) was investigated. Cytosolic Ca2+ movements provoked by X/XO consisted of an initial Ca2+ release from thapsigargin‐sensitive intracellular Ca2+ stores and a sustained Ca2+ influx through cell‐membrane Ca2+ channels. The Ca2+ movements from both sources were inhibited by catalase, cell‐membrane permeable iron chelators (o‐phenanthroline and deferoxamine), a •OH scavenger (5,5‐dimethyl‐1‐pyrroline‐N‐oxide), or an anion channel blocker (disodium 4, 4′‐diisothiocyano‐2, 2′‐stilbenedisulphonic acid), suggesting that •O2− influx through anion channels was responsible for the Ca2+ movements, in which •OH generation catalyzed by intracellular transition metals (i.e., Haber‐Weiss cycle) was involved. After an initial Ca2+ elevation provoked by X/XO, cytosolic Ca2+ concentration decreased to a level higher than basal levels. Removal of X/XO slightly enhanced the Ca2+ decrease. Extracellular addition of sulphydryl (SH)‐reducing agents, dithiothreitol or glutathione, after the removal of X/XO accelerated the decrement. A Ca2+ channel blocker, Ni2+, abolished the sustained increase in Ca2+, suggesting that Ca2+ influx through cell‐membrane Ca2+ channels was extracellularly regulated by the redox state of SH‐groups. The X/XO‐provoked change in cellular respiration was inhibited by Ni2+ or dithiothreitol as well as inhibitors of Haber‐Weiss cycle, suggesting that Ca2+ influx was responsible for •OH‐mediated cytotoxicity. We concluded that intracellular •OH generation was involved in the Ca2+ movements in endothelial cells exposed to X/XO. Cytosolic Ca2+ elevation was partly responsible for the oxidants‐mediated cytotoxicity. British Journal of Pharmacology (1999) 126, 1462–1470; doi:10.1038/sj.bjp.0702438