Alveolar cells: incorporation of carbohydrate into protein and evidence for intracellular protein transport

A B S T R A C T Bacterial infection may complicate pulmonary oxygen (02) toxicity, and animals exposed to high 02 concentrations show depressed in vivo pulmonary bacterial inactivation. Therefore, in vitro studies were undertaken to define the mechanism by which 02 alters pulmonary antibacterial activity. Normal and BCG pretreated rabbits were exposed to 100% 02 for 24, 48, and 72-h periods. Pulmonary alveolar macrophages (PAM) were obtained from the experimental animals and from nonoxygen exposed controls by bronchopulmonary lavage. 02 exposure did not alter cell yield or morphology. PAMs were suspended in 10% serum-buffer, and phagocytosis of ["C]Staphylococcus aureus 502A and ["C]Pseudomonas aeruginosa was measured. Comparison of the percent uptake of the "Clabeled S. aureus after a 60-min incubation period demonstrated that normal PAMs exposed to 02 for 48 h showed a statistically significant increase in phagocytosis when compared to their controls (43.5 vs. 29.2%). A similar, but smaller, increase was seen after 24-h 02 exposures. 48 and 72-h 02 exposures produced no significant changes in phagocytosis in PAMs from BCG-stimulated rabbits. Normal PAMs also showed an increased phagocytosis of Ps. aeruginosa after 48-h oxygen exposures. No impairment of in vitro bactericidal activity against either S. aureus 502A or Ps. aeruginosa could be demonstrated in PAMs from normal rabbits exposed to 02 for 48 h. These results indicate that the in vitro phagocytic and bactericidal capacity of the rabbit PAM is relatively resistant to the

Section: Methodsmentioning

confidence: 99%

Effects of oxygen exposure on in vitro function of pulmonary alveolar macrophages.

Murphey¹,

Hyams²,

Fisher³

et al. 1975

“…The tissue proteins and the proteins in the surface-active lung fraction were precipitated with trichloroacetic acid (TCA),1 extracted with lipid solvents and hot TCA, and assayed for radioactivity and protein content as previously described (6,7). The hot TCA-soluble material from the crude extracts was saved for measurement of DNA content relative to the amount of acid-insoluble radioactivity.…”

Section: Introductionmentioning

confidence: 99%

Hyperoxia: Influence on Lung Mechanics and Protein Synthesis

Gacad¹,

Massaro²

1973

Self Cite

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.

“…Carrier albumin was added to the lavage and tissue surface-active fraction and protein was precipitated with trichloroacetic acid (TCA). The precipitated material was extracted with lipid solvents and hot TCA and assayed for radioactivity as previously described (24,25).…”

Section: Methodsmentioning

confidence: 99%

In vivo protein secretion by lung. Evidence for active secretion and interspecies differences.

Massaro¹

1975

A B S T R A C T The present study is an attempt to determine (a) if the lung actively secretes protein into the surface-active fraction of lung lavage returns; (b) if there are interspecies differences in this secretory activity; and (c) if the amount of nonradioactive protein in the lavage surface-active fraction shows interspecies variation.I found that pilocarpine stimulates the release of radioactive protein into the lavage surface-active fraction of rabbits and that this pilocarpine effect is completely blocked by atropine. Inhibition of lung oxygen consumption by iodoacetate is associated with a dosedependent inhibition of the pilocarpine-induced secretion. Microtubules may be involved in this secretory process because colchicine inhibits the pilocarpine effect.Of the radioactive protein in the total surface-active fraction (tissue plus lavage returns), a greater percent appears in the lavage surface-active fraction at 2 and 4 h, after a pulsed injection of [U-'4C]leucine, in the mouse than in the rat, which in turn has a greater amount than the rabbit. There is also a difference in the amount of nonradioactive protein per square meter of alveolar surface area in the lavage surface-active fraction of different species: mouse> rat> rabbit> cat> dog. The amount of nonradioactive protein per square meter of alveolar surface area in the lavage surfaceactive fraction is directly proportional to the species respiratory rate; the log of the nonradioactive protein in the lavage surface-active fraction is inversely proportional to the log of the species alveolar diameter.