Peroxynitrite is a major trigger of cardiomyocyte apoptosis in vitro and in vivo.
Recent evidence indicates that peroxynitrite represents a major cytotoxic effector in heart diseases, but its mechanisms of action are still not known exactly. Notably, the ability of peroxynitrite to trigger cardiomyocyte apoptosis, a crucial mode of cell death in many cardiac conditions, remains poorly defined. We evaluated apoptotic and necrotic cell death in cultured H9C2 cardiomyocytes, following a brief (20 min) exposure to peroxynitrite (50-500 microM). Peroxynitrite-dependent myocardial toxicity was then investigated in a rat model of myocardial ischemia-reperfusion (MIR), where the effects of peroxynitrite were blocked by the superoxide dismutase mimetics and peroxynitrite scavenger Mn(III)-tetrakis(4-benzoic acid) porphyrin (MnTBAP). In vitro, peroxynitrite killed cardiomyocytes mostly through apoptosis (DNA fragmentation, apoptotic nuclear alterations, caspase-3 activation, and PARP cleavage), but not necrosis (propidium iodide staining and LDH release). In vivo, MIR triggered myocardial oxidative stress (malondialdehyde generation), nitrotyrosine formation, neutrophil accumulation, and the cleavage of caspase-3 and PARP, indicating ongoing myocardial apoptosis. MnTBAP suppressed these alterations, allowing a considerable reduction of myocardial injury. Thus, peroxynitrite triggers apoptosis in cardiomyocytes in vitro and in the myocardium in vivo, through a pathway involving caspase-3 activation and the cleavage of PARP. These results provide important novel information on the mechanisms of myocardial toxicity of peroxynitrite.
Levrand
Sandra
S
Department of Intensive Care Medicine, BH 10-982, University Hospital, 1011 Lausanne, Switzerland.
Vannay-Bouchiche
Christine
C
Pesse
Benoît
B
Pacher
Pal
P
Feihl
François
F
Waeber
Bernard
B
Liaudet
Lucas
L
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects / Q000473:pathology; D002470:Cell Survival / Q000187:drug effects; D006321:Heart / Q000187:drug effects; D008297:Male; D032342:Muscle Cells / Q000166:cytology* / Q000187:drug effects / Q000473:pathology; D017202:Myocardial Ischemia / Q000473:pathology; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000166:cytology* / Q000473:pathology; D030421:Peroxynitrous Acid / Q000633:toxicity*; D011065:Poly(ADP-ribose) Polymerases / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D030421:Peroxynitrous Acid; D011065:Poly(ADP-ribose) Polymerases; D020169:Caspases