Hypoxia/reoxygenation of isolated rat heart mitochondria causes cytochrome c release and oxidative stress; evidence for involvement of mitochondrial nitric oxide synthase.
The objective of the present study was to delineate the molecular mechanisms for mitochondrial contribution to oxidative stress induced by hypoxia and reoxygenation in the heart. The present study introduces a novel model allowing real-time study of mitochondria under hypoxia and reoxygenation, and describes the significance of intramitochondrial calcium homeostasis and mitochondrial nitric oxide synthase (mtNOS) for oxidative stress. The present study shows that incubating isolated rat heart mitochondria under hypoxia followed by reoxygenation, but not hypoxia per se, causes cytochrome c release from the mitochondria, oxidative modification of mitochondrial lipids and proteins, and inactivation of mitochondrial enzymes susceptible to inactivation by peroxynitrite. These alterations were prevented when mtNOS was inhibited or mitochondria were supplemented with antioxidant peroxynitrite scavengers. The present study shows mitochondria independent of other cellular components respond to hypoxia/reoxygenation by elevating intramitochondrial ionized calcium and stimulating mtNOS. The present study proposes a crucial role for heart mitochondrial calcium homeostasis and mtNOS in oxidative stress induced by hypoxia/reoxygenation.
Zenebe
Woineshet J
WJ
Department of Surgery, Davis Heart and Lung Research Institute, and Institute of Mitochondrial Biology, The Ohio State University, 460 West 12th Avenue, Columbus, Ohio 43210, USA.
Nazarewicz
Rafal R
RR
Parihar
Mordhwaj S
MS
Ghafourifar
Pedram
P
D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000502:physiology; D045304:Cytochromes c / Q000378:metabolism*; D006321:Heart / Q000187:drug effects*; D000860:Hypoxia / Q000378:metabolism*; D066298:In Vitro Techniques; D008929:Mitochondria, Heart / Q000201:enzymology*; D008954:Models, Biological; D015428:Myocardial Reperfusion Injury / Q000473:pathology; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D019001:Nitric Oxide Synthase / Q000502:physiology*; D018384:Oxidative Stress; D010100:Oxygen / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D045304:Cytochromes c; D019001:Nitric Oxide Synthase; D010100:Oxygen; D002118:Calcium