Abstract
Eighty-two 3-day-old rabbits were given by intratracheal injection doses of either radiolabeled natural sheep surfactant (NS) or sonicated suspensions of dipalmitoylphosphatidylcholine (DPPC) that contained >4x the endogenous phosphatidylcholine (PC) surfactant pool size. Recoveries of radiolabeled PC, total PC and PC specific activities (cpm/μmol PC) in alveolar washes (AW), lung tissue (L), and the total lung (AW+L) were measured over 72 hrs. More than half of the NS rapidly became L associated, and the labeled PC was linearly and slowly cleared from AW+L (0.28% of the initial injected cpm/hr). The alveolar surfactant pool size continued to increase despite the exogenously administered NS. Sonicated suspensions of DPPC were cleared from the AW+L at 0.71%/hr and only 15% of DPPC became L associated. The administration of large amounts of NS did not decrease the amount of intravenously injected radiolabeled choline, palmitic acid or 32P incorporated into lung PC or the amount of labeled PC secreted to the alveoli. Conclusions: 1) The % of injected PC associated with the L was higher and the rate of clearance from AW+L slower after a large dose of NS compared to an equivalent dose of DPPC. 2) Large doses of natural surfactant did not change endogenous synthetic and secretory rates. 3) Thus, the surfactant pool size apparently was not autoregulated by the animals following the administration of large doses of surfactant.
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Oguchi, K., Ikegami, M., Jacobs, H. et al. CLEARANCE OF LARGE AMOUNTS OF NATURAL SURFACTANT AND DIPALMITOYLPHOSPHATIDYLCHOLINE FROM THE LUNGS OF 3-DAY-OLD RABBITS FOLLOWING TRACHEAL INJECTION. Pediatr Res 18 (Suppl 4), 337 (1984). https://doi.org/10.1203/00006450-198404001-01465
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DOI: https://doi.org/10.1203/00006450-198404001-01465