title: Cell death during ischemia: relationship to mitochondrial depolarization and ROS generation.
abstract: Ischemia-reperfusion injury induces cell death, but the responsible mechanisms are not understood. This study examined mitochondrial depolarization and cell death during ischemia and reperfusion. Contracting cardiomyocytes were subjected to 60-min ischemia followed by 3-h reperfusion. Mitochondrial membrane potential (DeltaPsi(m)) was assessed with tetramethylrhodamine methyl ester. During ischemia, DeltaPsi(m) decreased to 24 +/- 5.5% of baseline, but no recovery was evident during reperfusion. Cell death assessed by Sytox Green was minimal during ischemia but averaged 66 +/- 7% after 3-h reperfusion. Cyclosporin A, an inhibitor of mitochondrial permeability transition, was not protective. However, pharmacological antioxidants attenuated the fall in DeltaPsi(m) during ischemia and cell death after reperfusion and decreased lipid peroxidation as assessed with C11-BODIPY. Cell death was also attenuated when residual O(2) was scavenged from the perfusate, creating anoxic ischemia. These results suggested that reactive oxygen species (ROS) were important for the decrease in DeltaPsi(m) during ischemia. Finally, 143B-rho(0) osteosarcoma cells lacking a mitochondrial electron transport chain failed to demonstrate a depletion of DeltaPsi(m) during ischemia and were significantly protected against cell death during reperfusion. Collectively, these studies identify a central role for mitochondrial ROS generation during ischemia in the mitochondrial depolarization and subsequent cell death induced by ischemia and reperfusion in this model.
authors.affiliation: Pulmonary and Critical Care Medicine, University of Chicago, Illinois 60637, USA.
authors.forename: Jacques
authors.initials: J
authors.lastname: Levraut
authors.forename: Hirotaro
authors.initials: H
authors.lastname: Iwase
authors.forename: Z-H
authors.initials: ZH
authors.lastname: Shao
authors.forename: Terry L
authors.initials: TL
authors.lastname: Vanden Hoek
authors.forename: Paul T
authors.initials: PT
authors.lastname: Schumacker
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D002642:Chick Embryo; D004579:Electron Transport / Q000502:physiology; D004594:Electrophysiology; D008054:Lipid Peroxides / Q000037:antagonists & inhibitors; D008564:Membrane Potentials; D008929:Mitochondria, Heart / Q000502:physiology*; D017202:Myocardial Ischemia / Q000503:physiopathology*; D015428:Myocardial Reperfusion Injury / Q000503:physiopathology; D018384:Oxidative Stress / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D008054:Lipid Peroxides; D017382:Reactive Oxygen Species