Reactive species mediated injury of human lung epithelial cells after hypoxia-reoxygenation.
This study tested the hypothesis that hypoxia exposure predisposed lung epithelial cells to reactive oxygen species-(ROS) mediated cellular injury. Human lung carcinoma cells (ATCC line H441) having epithelial characteristics (including lamellar bodies, surfactant protein [SP]-A, and SP-B) were cultured in air (air/5% CO(2)) or hypoxia (< 1% O(2)/5% CO(2)) for 0 to 24 hours before imposition of oxidant stress. Cellular manganese superoxide dismutase (MnSOD) activity (units/mg protein) decreased significantly after 24 hours of hypoxia. In normoxic culture after hypoxia, the cells produced increased ROS, detected as dichlorofluorescein (DCF) fluorescence and H(2)O(2) accumulation in medium. Antioxidants N-acetylcysteine (N-Ac) and ebselen inhibited increased DCF fluorescence after hypoxia. To test their ability to tolerate oxidant stress, some cells were incubated with antimycin A (100 microM) and trifluorocarbonylcyanide phenylhydrazone (10 microM) (anti A + FCCP), a mitochondrial complex III inhibitor and respiratory chain uncoupler, which together increase mitochondrial superoxide (O(2)(-)) and H(2)O(2) production. Lung epithelial cells preexposed to hypoxia released more lactate dehydrogenase (LDH) than normoxic controls in response to increased O(2)(-) production. Increased LDH release from hypoxia-preexposed cells treated with anti A + FCCP was inhibited by 1 mM N-Ac. Rotenone and myxothiazole increased DCF oxidation more in hypoxic than in normoxic cells, suggesting that mitochondrial electron transport complex I may have been altered by hypoxia preexposure.
Li
Chuanyu
C
Birmingham DVAMC, Birmingham, Alabama, USA.
Wright
Marcienne M
MM
Jackson
Robert M
RM
D000231:Adenocarcinoma, Papillary; D000255:Adenosine Triphosphate / Q000378:metabolism; D017304:Annexin A5 / Q000032:analysis; D017209:Apoptosis / Q000502:physiology; D002245:Carbon Dioxide / Q000494:pharmacology; D015687:Cell Hypoxia / Q000502:physiology*; D019281:Dimerization; D004847:Epithelial Cells / Q000737:chemistry / Q000378:metabolism*; D004996:Ethidium; D005452:Fluoresceins; D005456:Fluorescent Dyes; D005978:Glutathione / Q000378:metabolism; D019803:Glutathione Disulfide / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008175:Lung Neoplasms; D008928:Mitochondria / Q000378:metabolism; D009336:Necrosis; D018384:Oxidative Stress / Q000502:physiology; D010100:Oxygen / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000502:physiology; D020545:Respiratory Mucosa / Q000166:cytology* / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014475:Uncoupling Agents / Q000494:pharmacology
C110400:2',7'-dichlorodihydrofluorescein diacetate; D017304:Annexin A5; D005452:Fluoresceins; D005456:Fluorescent Dyes; D014475:Uncoupling Agents; D013481:Superoxides; D002245:Carbon Dioxide; C085925:calcein AM; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D013482:Superoxide Dismutase; D004996:Ethidium; D005978:Glutathione; D010100:Oxygen; D019803:Glutathione Disulfide