title: Hyperoxia decreases glycolytic capacity, glycolytic reserve and oxidative phosphorylation in MLE-12 cells and inhibits complex I and II function, but not complex IV in isolated mouse lung mitochondria.
abstract: High levels of oxygen (hyperoxia) are frequently used in critical care units and in conditions of respiratory insufficiencies in adults, as well as in infants. However, hyperoxia has been implicated in a number of pulmonary disorders including bronchopulmonary dysplasia (BPD) and adult respiratory distress syndrome (ARDS). Hyperoxia increases the generation of reactive oxygen species (ROS) in the mitochondria that could impair the function of the mitochondrial electron transport chain. We analyzed lung mitochondrial function in hyperoxia using the XF24 analyzer (extracellular flux) and optimized the assay for lung epithelial cells and mitochondria isolated from lungs of mice. Our data show that hyperoxia decreases basal oxygen consumption rate (OCR), spare respiratory capacity, maximal respiration and ATP turnover in MLE-12 cells. There was significant decrease in glycolytic capacity and glycolytic reserve in MLE-12 cells exposed to hyperoxia. Using mitochondria isolated from lungs of mice exposed to hyperoxia or normoxia we have shown that hyperoxia decreased the basal, state 3 and state3 μ (respiration in an uncoupled state) respirations. Further, using substrate or inhibitor of a specific complex we show that the OCR via complex I and II, but not complex IV was decreased, demonstrating that complexes I and II are specific targets of hyperoxia. Further, the activities of complex I (NADH dehydrogenase, NADH-DH) and complex II (succinate dehydrogenase, SDH) were decreased in hyperoxia, but the activity of complex IV (cytochrome oxidase, COX) remains unchanged. Taken together, our study show that hyperoxia impairs glycolytic and mitochondrial energy metabolism in in tact cells, as well as in lungs of mice by selectively inactivating components of electron transport system.
authors.affiliation: Department of Anesthesiology, Texas Tech University Health Sciences Center, Lubbock, Texas, United States of America.
authors.forename: Kumuda C
authors.initials: KC
authors.lastname: Das
mesh_terms: D000818:Animals; D002460:Cell Line; D004579:Electron Transport; D042967:Electron Transport Complex I / Q000378:metabolism*; D042963:Electron Transport Complex II / Q000378:metabolism*; D003576:Electron Transport Complex IV / Q000378:metabolism; D004734:Energy Metabolism; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D006019:Glycolysis; D008168:Lung / Q000166:cytology*; D008297:Male; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D010085:Oxidative Phosphorylation; D010100:Oxygen / Q000378:metabolism*
chemical_list: D042963:Electron Transport Complex II; D003576:Electron Transport Complex IV; D042967:Electron Transport Complex I; D010100:Oxygen
references.citation: Biochim Biophys Acta. 1964 Nov 22;92:233-47
references.pmid: 14249115
references.citation: J Appl Physiol Respir Environ Exerc Physiol. 1979 Jul;47(1):98-103
references.pmid: 224021
references.citation: Free Radic Biol Med. 1988;4(6):345-56
references.pmid: 3384344
references.citation: Am J Physiol Lung Cell Mol Physiol. 2001 Apr;280(4):L779-91
references.pmid: 11238020
references.citation: Proc Natl Acad Sci U S A. 1981 May;78(5):3185-9
references.pmid: 6265940
references.citation: J Biol Chem. 2004 Nov 5;279(45):46580-7
references.pmid: 15328348
references.citation: J Biol Chem. 1993 Dec 15;268(35):26699-703
references.pmid: 8253804
references.citation: J Clin Invest. 1993 Jan;91(1):46-52
references.pmid: 8380815
references.citation: J Cell Biol. 1966 Jul;30(1):45-57
references.pmid: 4226009
references.citation: Proc Natl Acad Sci U S A. 1994 Dec 6;91(25):12248-52
references.pmid: 7991614
references.citation: J Bioenerg Biomembr. 2005 Oct;37(5):327-38
references.pmid: 16341777
references.citation: J Cell Biol. 1971 Jul;50(1):20d-55d
references.pmid: 4327465
references.citation: J Cell Physiol. 1976 Oct;89(2):235-49
references.pmid: 972165
references.citation: J Biol Chem. 1981 Nov 10;256(21):10986-92
references.pmid: 7287745
references.citation: Am J Physiol. 1998 Jan;274(1):L159-64
references.pmid: 9458814
references.citation: Am J Respir Cell Mol Biol. 1999 Sep;21(3):395-402
references.pmid: 10460757
references.citation: Am J Respir Cell Mol Biol. 2009 May;40(5):511-8
references.pmid: 19168698
references.citation: J Pediatr. 1984 Jun;104(6):928-31
references.pmid: 6547171
references.citation: J Biol Chem. 1990 Jul 5;265(19):1118-24
references.pmid: 2358458
references.citation: Biochem J. 2011 Apr 15;435(2):297-312
references.pmid: 21726199
references.citation: J Clin Monit Comput. 2012 Aug;26(4):255-65
references.pmid: 22437884
references.citation: PLoS One. 2011;6(7):e21746
references.pmid: 21799747
references.citation: J Biochem Mol Biol. 2004 Jul 31;37(4):454-9
references.pmid: 15469733
references.citation: Biochim Biophys Acta. 2001 Feb 5;1538(1):90-7
references.pmid: 11341986
references.citation: J Physiol. 2003 Oct 15;552(Pt 2):335-44
references.pmid: 14561818
references.citation: J Biol Chem. 1984 Nov 25;259(22):13791-9
references.pmid: 6094530
references.citation: Am J Physiol. 1998 Mar;274(3):L320-9
references.pmid: 9530166
references.citation: Crit Care. 2007;11(2):126
references.pmid: 17466082
references.citation: Anal Biochem. 1987 Feb 15;161(1):1-15
references.pmid: 3578775