Effects of hyperoxia and beta-adrenergic stimulation on pulmonary surfactant in neonatal rabbits.
To study the effects of hyperoxia and beta-adrenergic stimulation on pulmonary surfactant in the neonatal lung, we measured disaturated phosphatidylcholine (DSPC) and [14C]choline incorporation into DSPC, obtained from alveolar lavage and lung tissue. We used an isolated salt-perfused rabbit lung preparation from neonatal rabbits exposed to room air or greater than 95% oxygen for 3 days. There were four experimental groups: room air, basal condition; room air, beta-adrenergic stimulation; hyperoxia, basal conditions; and hyperoxia, beta-adrenergic stimulation. Hyperoxia caused a significant decrease in lavage and intracellular [14C]DSPC specific activity, and a decrease in intracellular DSPC suggesting depressed surfactant synthesis. Beta-stimulation in room air caused a decrease in lavage DSPC, an increase in DSPC, and [14C]DSPC fraction released, consistent with increased uptake for reutilization. With hyperoxia and beta-stimulation, there is an increase in total DSPC in the lavage; lavage [14C]DSPC specific activity is similar to that of the basal hyperoxia group (i.e., depressed compared with the room air state); intracellular [14C]DSPC specific activity does not differ from basal, hyperoxia, or beta-stimulated, room air groups, all being depressed compared with basal, room air conditions. Intracellular DSPC in the beta-stimulated group is less affected by hyperoxia than the basal groups. It appears that prolonged exposure to hyperoxia is manifested primarily by a decrease in [14C]DSPC specific activity suggesting alterations in surfactant synthesis, though DSPC in the lavage is not altered. Beta-adrenergic stimulation may enhance release of newly synthesized surfactant into the alveoli, and possibly enhances uptake for reutilization. The enhancement of surfactant release seems to be preserved after prolonged hyperoxia.
Polak
M J
MJ
Department of Pediatrics, West Virginia University School of Medicine, Morgantown 26506.
Knight
M E
ME
Andresen
T L
TL
DeSena
C
C
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D008055:Lipids / Q000032:analysis; D010100:Oxygen / Q000494:pharmacology*; D010477:Perfusion; D010713:Phosphatidylcholines / Q000032:analysis; D011663:Pulmonary Surfactants / Q000187:drug effects*; D011817:Rabbits; D051381:Rats
D000318:Adrenergic beta-Agonists; D008055:Lipids; D010713:Phosphatidylcholines; D011663:Pulmonary Surfactants; D010100:Oxygen