Endotoxin Protection against Pulmonary Oxygen Toxicity and Plasma Prostaglandin Levels in the Rat
Exposure of rats to high concentrations of oxygen (> 95%) at 1 ATA pressure (101 kPa) is lethal within three days. Rats treated with a small dose of endotoxin are protected against these lethal effects of hyperoxia. Recently, we found that the lysine salt of acetylsalicylic acid antagonises this protective action of endotoxin. This suggests that prostaglandin metabolism plays an important role in the protective action of endotoxin against pulmonary oxygen toxicity. Therefore, we measured the plasma levels of 6KPGF1∝, a stable degradation product of prostacyclin (PGI2), PGE2 and thromboxane B2, the stable degradation product of thromboxane A2, in rats exposed to air or > 95% oxygen for 48 hours. We compared these with the plasma levels of rats treated with endotoxin (Salmonella typhimurium lipopolysaccharide 1 mg/kg) and exposed to air or > 95% oxygen for 48 hours. We found that exposure of rats to > 95% oxygen for 48 hours leads to a significant rise in the 6KPGF1∝ levels. Rats exposed to > 95% oxygen for 48 hours and treated with endotoxin had significantly higher PGE2 and significantly lower 6KPGF1∝ plasma levels than saline-treated rats exposed to > 95% oxygen for 48 hours.
KeywordsOxygen Toxicity MANN WHITNEY High PGE2 Prostaglandin Metabolism Pulmonary Oxygen Toxicity
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