Hyperoxia: Influence on Lung Mechanics and Protein Synthesis

Abstract

A B S T R A C T 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% 02 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-'4C] leucine incorporation into protein, lung slices were incubated with L-[U-J4C] 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 hyperoxia. After 24 h of hyperoxia there were significant decreases (P < 0.05) in L-[U-24C]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.

Hyperoxia: A Stereologic Ultrastructural Examination of Its Influence on Cytoplasmic Components of the Pulmonary Granular Pneumocyte

“…The present work has shown that the size of lamellar bodies of rats exposed to hyperoxia for 48 h are smaller Hyperoxia decreased the incorporation of ["4C]leucine into protein in a surface-active lung fraction (7), to about the same extent as the decrease in lamellar body size. Thus, it would appear that in the face of a hyperoxia-induced decrease in synthesis of secretory protein the "packages" for export are smaller.…”

“…We have shown that incorporation of [14C]leucine into protein of a surface active lung fraction, is decreased after in vivo exposure of rats to hyperoxia (7). These considerations make it reasonable to suspect that the decreased incorporation of [14C]leucine into protein of the surfaceactive lung fraction in rats exposed to hyperoxia might be reflected in alterations in the size, number, or both of these storage sites.…”

“…We used Dublin Sprague-Dawley derived male rats (Flow Research Animals, Inc., Dublin, Va.). They were exposed to greater than 98% 02 or air for 48 h as previously described (7).…”

Adaption to Hyperoxia

“…Received for publication 30 July 1973 and in revised form 12 November 1973. protein synthesis by lung (1). The decrease in the synthesis of protein in a surface-active fraction is greater than the decrease in synthesis of protein in the whole lung homogenate.…”

“…METHODS Animals. We used Dublin-Sprague Dawley-derived male rats (Flow Research Animals Inc., Dublin, Va.) weighing between 100-125 g. They were exposed to oxygen (> 98%o) or compressed air and sacrificed as previouslydescribed (1).…”