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The significance of reutilization of surfactant phosphatidylcholine.

1983; Elsevier BV; Volume: 258; Issue: 7 Linguagem: Inglês

10.1016/s0021-9258(18)32599-7

1083-351X

Harris C. Jacobs, Alan H. Jobe, M. Ikegami, D Conaway,

Biomedical Research and Pathophysiology

To assess the magnitude of reutilization of surfactant phosphatidylcholine, 68 3-day-old rabbits were injected intratracheally with a trace dose of [3H]choline-labeled surfactant mixed with [14C]palmitate-labeled synthetic dipalmitoylphosphatidylcholine.After timed kills we measured the total phosphatidylcholine associated counts/& in whole lung and alveolar wash and the specific activities of phosphatidylcholine in the alveolar wash, lamellar bodies, and microsomes isolated from the lung of each rabbit.Using a modification of the compartment analysis of Skinner et aL (Skinner, S. M., Clark, R. E., Baker, N., and Shipley, R. A. (1959) A m J. PhysioL 196,[238][239][240][241][242][243][244], we found that surfactant phosphatidylcholine was reutilized with greater than 90% efficiency.The turnover time of the alveolar wash phosphatidylcholine was estimated to be 10.1 h and 9.3 h as measured by the 'H and 14C labels, respectively.From the ratios of alveolar wash-associated natural t o synthetic phosphatidylcholine specific activities and from similar ratios obtained in 30 additional rabbits using ['4C]choline-labeled natural surfactant and [3H]cholinelabeled dipalmitoylphosphatidylcholine, we showed that phosphatidylcholine was reutilized intact rather than as component parts.Within 6 h of injection, the synthetic dipalmitoylphosphatidylcholine functioned metabolically as that administered in the form of natural surfactant.