Endotoxin treatment protects vitamin E-deficient rats from pulmonary O2 toxicity.
Endotoxin treatment in normal rats has a marked protective effect against O2 toxicity (J. Appl. Physiol.: Respirat. Environ. Exercise Physiol. 47: 577-581, 1979 and 51: 577-583, 1981), and endotoxin's protective action is associated with stimulation of the lung's enzymatic antioxidant defense system (superoxide dismutase, catalase, glutathione peroxidase, and glucose-6-phosphate dehydrogenase). Vitamin E-deficient animals are especially sensitive to hyperoxidant stresses, including pulmonary O2 toxicity. In these studies we tested whether endotoxin could reverse the increased susceptibility of vitamin E-deficient rats to hyperoxic challenge. We found that untreated vitamin E-deficient rats do succumb more readily to O2 toxicity [0/11 alive at 72 h in greater than 95% O2, lethal time for 50% of the animals (LT50) = 50 h] than rats fed a regular diet (4/14 alive, LT50 = 69 h). In contrast, 15 of 16 vitamin E-deficient rats treated with endotoxin survived the same O2 exposures (P less than 0.001) and showed significantly reduced pulmonary edema compared with the other groups. The endotoxin-treated vitamin E-deficient group was also the only one to demonstrate significant elevations of all the antioxidant enzymes during O2 exposure, suggesting that the antioxidant enzyme defenses of the lung have a more primary and important role in prevention of O2-induced lung injury than the lipid-associated antioxidant, vitamin E.
D000818:Animals; D004198:Disease Susceptibility; D004731:Endotoxins / Q000627:therapeutic use*; D008168:Lung / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D009026:Mortality; D010088:Oxidoreductases / Q000032:analysis; D010100:Oxygen / Q000633:toxicity*; D011654:Pulmonary Edema / Q000150:complications; D051381:Rats; D011919:Rats, Inbred Strains; D012486:Salmonella typhimurium; D014811:Vitamin E Deficiency / Q000150:complications*
D004731:Endotoxins; D010088:Oxidoreductases; D010100:Oxygen