Human Fibroblast Antioxidant Defense Response to Alteration in Oxygen Tension
Our previous studies have revealed that partial pressures of oxygen (PO2) ranging from 6 through 720 mm Hg modulate growth of human diploid fibroblasts. We have demonstrated that even physiological oxygen concentrations (PO2 6 – 134 mm Hg) modulate the proliferative life span of these cells. Furthermore, proliferatively aged cells that exhibit a decreased growth rate are more sensitive to oxidative stress than are actively growing cells at lower population doubling levels. Inhibition of cell growth by partial pressures of oxygen above PO2 300 mm Hg and the limited proliferative capacity of cells in culture under physiological oxygen concentrations are probably distinct phenomena resulting from different mechanisms. Our studies indicate that fibroblasts contain multiple oxygen-sensitive sites which exhibit differential sensitivity to oxygen; however, total cellular metabolism is not generally inhibited by hyperoxic exposure. Thus, oxygen-induced inhibition of cell growth may result from a relatively selective process.1
KeywordsGlutathione Peroxidase Oxygen Tension Confluent Cell Glutathione Peroxidase Activity Human Diploid Fibroblast
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