H2O2 mediates O2 toxicity in cultured fetal rat distal lung epithelial cells.
It is unknown which of the reactive oxygen species is primarily responsible for the cytotoxicity of 95% O2 for rat distal fetal lung epithelial cells in vitro. Incubation of cells with 25 U/ml polyethylene glycol (PEG)-conjugated SOD and 50 U/ml PEG-catalase, but not PEG-SOD or SOD mimics alone, significantly reduced 95% O2-mediated cytotoxicity. Liposome-entrapped catalase, without SOD, also significantly reduced 95% O2-mediated cytotoxicity. Increased formation of lipid hydroperoxides, as assessed by the formation of 8-isoprostane and aldehydes, was attenuated by both 100 microM Trolox, a vitamin E analogue, and by 5 microM U74389G, an amino steroid. Trolox, but not U74389G, prevented an increase in cell-derived H2O2, hydroxyl radical and 95% O2-mediated cytotoxicity. An increase in hydroxyl radical formation, but not cell death, observed in 95% O2, was prevented by 0.1 microM phenanthrolene, a cell permeant iron chelator. DNA extracts of rat distal fetal lung epithelial cells maintained under serum-free conditions had an electrophoretic pattern consistent with some degree of apoptosis. However, no increase in laddering was seen with exposure to 95% O2. These data are consistent with hydrogen peroxide, but not lipid hydroperoxides or hydroxyl radical, being a critical effector of O2-mediated necrotic cell death in distal lung epithelial cells.
Luo
X
X
Hospital for Sick Children Research Institute, Department of Paediatrics, University of Toronto, Ontario, Canada.
Christie
N A
NA
McLaughlin
M A
MA
Belcastro
R
R
Sedlackova
L
L
Cabacungan
J
J
Freeman
B A
BA
Tanswell
A K
AK
D000704:Analysis of Variance; D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects; D002374:Catalase / Q000378:metabolism; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000633:toxicity*; D008168:Lung / Q000187:drug effects* / Q000196:embryology / Q000473:pathology; D009336:Necrosis; D010100:Oxygen / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D013481:Superoxides / Q000378:metabolism
D000975:Antioxidants; D013481:Superoxides; D006861:Hydrogen Peroxide; D002374:Catalase; D010100:Oxygen