Reoxygenation of the hypoxic myocardium results in a number of processes, including an O2-dependent increase in total tissue Ca2+ and cell lysis in which mitochondrial electron transport plays a key role. In the present study we have isolated mitochondria from perfused rat hearts subjected to hypoxia and found no change in their respiratory function relative to controls. In contrast, mitochondria isolated immediately after reoxygenation of hypoxic-perfused hearts exhibited a specific and significant decrease in NADH:CoQ reductase (Complex I; EC 1.6.5.3) activity, as measured both polarographically and spectrophotometrically. Isolated cardiomyocytes subjected to a similar protocol of hypoxia/reoxygenation also exhibited a specific decrease in Complex I activity. Myocardial perfusion with media containing Ruthenium Red protected against the reoxygenation-dependent loss of Complex I activity. These observations taken together suggest that mitochondrial Ca2+ uptake on reoxygenation is implicated in the mechanism of the specific loss of Complex I activity.
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February 1991
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Research Article|
February 15 1991
Reoxygenation-dependent decrease in mitochondrial NADH:CoQ reductase (Complex I) activity in the hypoxic/reoxygenated rat heart
L Hardy;
L Hardy
*Biochemistry Department, St. Bartholomew's Hospital Medical College, Charterhouse Square, London ECIM 6BQ, U.K.
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J B Clark;
J B Clark
*Biochemistry Department, St. Bartholomew's Hospital Medical College, Charterhouse Square, London ECIM 6BQ, U.K.
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V M Darley-Usmar;
V M Darley-Usmar
†Biochemical Sciences, The Wellcome Research Laboratories, Beckenham, Kent BR3 3BS, U.K.
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D R Smith;
D R Smith
†Biochemical Sciences, The Wellcome Research Laboratories, Beckenham, Kent BR3 3BS, U.K.
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D Stone
D Stone
†Biochemical Sciences, The Wellcome Research Laboratories, Beckenham, Kent BR3 3BS, U.K.
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Biochem J (1991) 274 (1): 133–137.
Citation
L Hardy, J B Clark, V M Darley-Usmar, D R Smith, D Stone; Reoxygenation-dependent decrease in mitochondrial NADH:CoQ reductase (Complex I) activity in the hypoxic/reoxygenated rat heart. Biochem J 15 February 1991; 274 (1): 133–137. doi: https://doi.org/10.1042/bj2740133
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