title: Hormonal and local factors influence antioxidant enzyme activity of rat fetal lung cells in vitro.
abstract: Monolayer cultures of fetal rat mixed lung cells respond to sublethal concentrations (50%) of oxygen by a reduced growth rate. Exposure to 95% O2 causes growth arrest and cell loss. In the presence of serum the addition of dexamethasone (5.5 nM), tri-iodothyronine (5.5 nM), or insulin (5 microU/ml) appeared to increase the cytotoxicity of 95% O2. Under growth-arrested conditions, in the absence of serum or elevated O2 concentrations, all three agents influence cellular antioxidant enzyme activities. Dexamethasone (0.055 nM) increased CuZn superoxide dismutase activity by 72% and glutathione peroxidase activity by 94%. Triiodothyronine (5.5 nM) increased CuZn superoxide dismutase activity 93%. Insulin (5 microU/ml) increased CuZn superoxide dismutase activity 90%, and catalase activity 58%. Dexamethasone, but not tri-iodothyronine or insulin, seems to have a protective effect against subsequent acute hyperoxia under serum-free conditions. Local non-hormonal factors may also influence lung cell responses to acute increases in oxygen concentrations, since cells acutely exposed to 50% or 95% O2 release a transferable factor(s) into their culture medium which increases antioxidant enzyme activities of non-hyperoxic lung cells.
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003907:Dexamethasone / Q000494:pharmacology; D005333:Fetus / Q000378:metabolism*; D006728:Hormones / Q000502:physiology*; D007328:Insulin / Q000494:pharmacology; D008168:Lung / Q000166:cytology / Q000196:embryology* / Q000201:enzymology; D009994:Osmolar Concentration; D010100:Oxygen / Q000494:pharmacology; D051381:Rats / Q000196:embryology; D014284:Triiodothyronine / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D006728:Hormones; D007328:Insulin; D014284:Triiodothyronine; D003907:Dexamethasone; D010100:Oxygen