Effect of hydrogen peroxide on reoxygenation-induced Ca2+ accumulation in rat cardiomyocytes.
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.
Sharikabad
Mohammad Nouri
MN
Division of Clinical Pharmacology and Toxicology, Clinical Chemistry Department, Ullevaal University Hospital, Oslo, Norway. m.n.sharikabad@ioks.uio.no
Østbye
Kirsten Margrethe
KM
Brørs
Odd
O
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
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