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Free access | 10.1172/JCI107608
Pulmonary Division, Veterans Administration Hospital, Washington, D. C. 20422
Department of Medicine, George Washington University Medical Center, Washington, D. C. 20422
Find articles by Massaro, G. in: JCI | PubMed | Google Scholar
Pulmonary Division, Veterans Administration Hospital, Washington, D. C. 20422
Department of Medicine, George Washington University Medical Center, Washington, D. C. 20422
Find articles by Massaro, D. in: JCI | PubMed | Google Scholar
Published March 1, 1974 - More info
We studied the influence of prolonged exposure to hyperoxia (O2 > 98%) on protein synthesis and on the ultrastructure of the granular pneumocyte. To study protein synthesis, as indicated by l-[U-14C]-leucine incorporation into protein, lung slices were incubated with radioactive leucine and a surface-active fraction was obtained by ultracentrifugation of lung homogenates. We found that, following an initial depression in protein synthesis after 48 h of hyperoxia, protein synthesis in rats exposed to oxygen for 96 h rose to greater than control levels. This increase in protein synthesis was noted in whole lung protein and in protein present in the surface-active fraction.
Stereologic ultrastructural analysis of granular pneumocytes revealed that the lamellar bodies occupy the same percentage of cytoplasmic volume in oxygen-exposed and control rats after 96 h; a previous study had shown lamellar bodies of oxygen-exposed rats to occupy less volume than those of control rats after 48 h of exposure at which time protein synthesis was also depressed. After 96 h of exposure there is a greater amount of rough endoplasmic reticulum in the granular pneumocytes of oxygen-exposed rats.
These studies show that after 96 h of hyperoxia the lung has recovered its ability to synthesize protein including protein in the surface-active fraction and that these biochemical changes are associated with consistent ultrastructural alterations in the granular pneumocyte.