Hyperoxia: influence on lung mechanics and protein synthesis.
We studied the time-course of the influence of in vivo hyperoxia on lung mechanics and on protein synthesis. After 24 h of exposure to greater than 98% O2 at 1 atm there were no alterations in descending pressure-volume curves (air or saline) of lungs excised from O2-exposed rats compared to control rats. After 48 h of hyperoxia there was a decrease in lung compliance. To study protein synthesis, as indicated by L-[U-(24)C] leucine incorporation into protein, lung slices were incubated with L-[U-(14)C]leucine and surface-active material then obtained by ultracentrifugation of lung homogenates. We measured radioactivity in total protein and in protein in the surface-active fraction. There were no alterations in incorporation after 12 h of hypertoxia. After 24 h of hyperoxia there were significant decreases (P<0.05) in L-[U-(14)C]leucine incorporation into total protein and into protein of the surface-active fraction. After 48 h of hyperoxia incorporation into protein of the surface-active fraction was decreased to a greater extent than incorporation into total protein, 63+/-4% and 75+/-5%, respectively, (P<0.025). These studies show that hyperoxia produces a major decrease in protein synthesis, including synthesis of protein in a surface-active fraction, before the onset of any detectable changes in the static compliance of excised lungs.
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002247:Carbon Isotopes; D004247:DNA / Q000032:analysis; D066298:In Vitro Techniques; D007930:Leucine / Q000378:metabolism; D008168:Lung / Q000032:analysis / Q000187:drug effects* / Q000378:metabolism; D008170:Lung Compliance / Q000187:drug effects; D008297:Male; D010100:Oxygen / Q000494:pharmacology*; D014176:Protein Biosynthesis; D011506:Proteins / Q000032:analysis; D011663:Pulmonary Surfactants / Q000378:metabolism; D012313:RNA / Q000032:analysis; D051381:Rats; D013997:Time Factors; D014364:Tryptophan / Q000494:pharmacology
D002247:Carbon Isotopes; D011506:Proteins; D011663:Pulmonary Surfactants; D012313:RNA; D014364:Tryptophan; D004247:DNA; D007930:Leucine; D010100:Oxygen