Selenium deficiency potentiates paraquat-induced lipid peroxidation in isolated perfused rat lung.
Glutathione peroxidase (GSHPx), a seleno-enzyme, reduces lipid hydroperoxides while producing oxidized glutathione (GSSG), which can efflux from cells. To study the role of GSHPx in antioxidant defense, isolated lungs from selenium-deficient rats were perfused for 2 h with or without 1 mM paraquat. Perfusate GSSG was measured as an index of GSHPx activity, and malondialdehyde (MDA) as an index of lipid peroxidation. Selenium deficiency decreased lung GSHPx activity 75-80%. During perfusion control lungs showed GSSG efflux of 8.5 +/- 4.5 nmol/h and with paraquat 49.1 +/- 12.1 nmol/h. Selenium-deficient lungs with or without paraquat showed GSSG efflux of 16.4 +/- 5.3 and 13.7 +/- 8.9 nmol/h, respectively. MDA efflux occurred only in paraquat-perfused selenium-deficient lungs (7.8 +/- 2.7 nmol/h). Lung homogenates from this group had lower GSH + GSSG than the other three groups. These results indicate an inverse correlation between GSSG efflux and MDA accumulation from paraquat-perfused lungs and suggest that increased turnover of the GSHPx reaction protects paraquat-perfused lungs from lipid peroxidation.
D000818:Animals; D005978:Glutathione / Q000378:metabolism; D005979:Glutathione Peroxidase / Q000378:metabolism*; D008054:Lipid Peroxides / Q000096:biosynthesis*; D008168:Lung / Q000378:metabolism*; D008315:Malondialdehyde / Q000378:metabolism; D010269:Paraquat / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012643:Selenium / Q000172:deficiency*
D008054:Lipid Peroxides; D008315:Malondialdehyde; D005979:Glutathione Peroxidase; D005978:Glutathione; D012643:Selenium; D010269:Paraquat