title: Reperfusion, not simulated ischemia, initiates intrinsic apoptosis injury in chick cardiomyocytes.
abstract: Although ischemia-reperfusion (I/R) can initiate apoptosis, the timing and contribution of the mitochondrial/cytochrome c apoptosis death pathway to I/R injury is unclear. We studied the timing of cytochrome c release during I/R and whether subsequent caspase activation contributes to reperfusion injury in confluent chick cardiomyocytes. One-hour simulated ischemia followed by 3-h reperfusion resulted in significant cell death, with most cell death evident during the reperfusion phase and demonstrating mitochondrial cytochrome c release within 5 min after reperfusion. By contrast, cells exposed to prolonged ischemia for 4 h had only marginally increased cell death and no detectable cytochrome c release into the cytosol. Caspase activation could not be detected after ischemia only, but it significantly increased after reperfusion. Caspase inhibitors benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone, Ac-Asp-Gln-Thr-Asp-H, or benzyloxycarbonyl-Leu-Glu (Ome)-His-Asp-(Ome)-fluoromethyl ketone given only at reperfusion significantly attenuated cell death and resulted in return of contraction. Antixoxidants decreased cytochrome c release, nuclear condensation, and cell death. These results suggest that reperfusion oxidants initiate cytochrome c release within minutes, and apoptosis within hours, significant enough to increase cell death and contractile dysfunction.
authors.affiliation: Sections of Emergency Medicine and Pulmonary/Critical Care, Department of Medicine and Emergency Resuscitation Center, University of Chicago, Illinois 60637, USA.
authors.forename: Terry L
authors.initials: TL
authors.lastname: Vanden Hoek
authors.forename: Yimin
authors.initials: Y
authors.lastname: Qin
authors.forename: Kim
authors.initials: K
authors.lastname: Wojcik
authors.forename: Chang-Qing
authors.initials: CQ
authors.lastname: Li
authors.forename: Zuo-Hui
authors.initials: ZH
authors.lastname: Shao
authors.forename: Travis
authors.initials: T
authors.lastname: Anderson
authors.forename: Lance B
authors.initials: LB
authors.lastname: Becker
authors.forename: Kimm J
authors.initials: KJ
authors.lastname: Hamann
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002467:Cell Nucleus / Q000648:ultrastructure; D002478:Cells, Cultured; D002642:Chick Embryo; D003574:Cytochrome c Group / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006321:Heart / Q000503:physiopathology*; D007511:Ischemia / Q000503:physiopathology; D008840:Microfilament Proteins / Q000737:chemistry / Q000378:metabolism; D032342:Muscle Cells / Q000502:physiology*; D009206:Myocardium / Q000473:pathology* / Q000648:ultrastructure; D015427:Reperfusion Injury / Q000503:physiopathology*; D013997:Time Factors; D013049:Spectrin
chemical_list: D000975:Antioxidants; D002352:Carrier Proteins; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases; D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D008840:Microfilament Proteins; D013049:Spectrin