title: Effect of hydrogen peroxide on reoxygenation-induced Ca2+ accumulation in rat cardiomyocytes.
abstract: Reactive oxygen species (ROS) contribute to cell damage during reperfusion of the heart. ROS may exert their effects partly by interfering with Ca(2+) homeostasis of the myocardium. The purpose of this study was to investigate the effects of hydrogen peroxide (H(2)O(2)) on Ca(2+) accumulation during reoxygenation of isolated adult rat cardiomyocytes exposed to 1 h of hypoxia and to relate the effects to possible changes in release of lactate dehydrogenase (LDH), free intracellular Ca(2+) ([Ca(2+)](i)) and Mg(2+)([Mg(2+)](i)), and mitochondrial membrane potential (Deltapsim). Cell Ca(2+) was determined by (45)Ca(2+) uptake. Free [Mg(2+)](i) and [Ca(2+)](i) and Deltapsim were measured by flow cytometry. Reoxygenation-induced Ca(2+) accumulation was attenuated by 23 and 34% by 10 and 25 microM H(2)O(2), respectively, added at reoxygenation. H(2)O(2) at 100 and 250 microM increased cell Ca(2+) by 50 and 83%, respectively, whereas 500 microM H(2)O(2) decreased cell Ca(2+) by 20%. H(2)O(2) at (25 microM) reduced LDH release and [Mg(2+)](i) and increased Deltapsim, indicating cell protection, whereas 250 microM H(2)O(2) increased LDH release and [Mg(2+)](i) and decreased Deltapsim, indicating cell damage. Clonazepam (100 microM) attenuated the increase in Ca(2+) accumulation, the elevation of [Ca(2+)](i), and the decrease in Deltapsim induced by 100 and 250 microM H(2)O(2) during reoxygenation. We report for the first time that 25 microM H(2)O(2) attenuates Ca(2+) accumulation, LDH release, and dissipation of Deltapsim during reoxygenation of hypoxic cardiomyocytes, indicating cell protection.
authors.affiliation: Division of Clinical Pharmacology and Toxicology, Clinical Chemistry Department, Ullevaal University Hospital, Oslo, Norway. m.n.sharikabad@ioks.uio.no
authors.forename: Mohammad Nouri
authors.initials: MN
authors.lastname: Sharikabad
authors.forename: Kirsten Margrethe
authors.initials: KM
authors.lastname: Østbye
authors.forename: Odd
authors.initials: O
authors.lastname: Brørs
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002021:Buffers; D002118:Calcium / Q000378:metabolism*; D002998:Clonazepam / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D005609:Free Radicals; D018757:GABA Modulators / Q000494:pharmacology; D006321:Heart / Q000502:physiology; D006706:Homeostasis; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D000860:Hypoxia; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology; D032383:Myocytes, Cardiac / Q000166:cytology*; D010100:Oxygen / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species; D013997:Time Factors
chemical_list: D002021:Buffers; D005609:Free Radicals; D018757:GABA Modulators; D017382:Reactive Oxygen Species; D002998:Clonazepam; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D008274:Magnesium; D010100:Oxygen; D002118:Calcium