Cellular uptake and processing of surfactant lipids and apoprotein SP-A by rat lung.

Published

Journal Article

The intracellular pathways and the kinetics of metabolism of surfactant apoprotein and lipid, which may be recycled from the alveolar space, are largely unknown. We used a lipid-apoprotein complex made from liposomes of pure lipids in a ratio found in mammalian pulmonary surfactant plus surfactant apoprotein (SP-A, Mr = 26,000-36,000) to test some possible relationships in the recycling of these major surfactant components between intrapulmonary compartments. After intratracheal instillation of 80 microliters of an apoprotein-liposome mixture with separate radiolabels in the lipid and the apoprotein, rats were killed at times from 8 min to 4 h later. The lungs were lavaged with saline, and subcellular fractions were isolated on discontinuous sucrose density gradients. Both the [14C]lipid radiolabel and the 125I-apoprotein radiolabel demonstrated a time-dependent increase in radioactivity recovered in a lamellar body-enriched fraction. Uptake of the radiolabels into other subcellular fractions did not exhibit a clear-cut time dependence; more of the protein than the lipid radiolabel was found in the Golgi-rich and microsomal fractions. We conclude that both the lipid and apoprotein portions of lung surfactant are taken up by lung cells and are incorporated into secretory granules of the cells.

Full Text

Duke Authors

Cited Authors

  • Young, SL; Wright, JR; Clements, JA

Published Date

  • March 1989

Published In

Volume / Issue

  • 66 / 3

Start / End Page

  • 1336 - 1342

PubMed ID

  • 2708254

Pubmed Central ID

  • 2708254

International Standard Serial Number (ISSN)

  • 8750-7587

Digital Object Identifier (DOI)

  • 10.1152/jappl.1989.66.3.1336

Language

  • eng

Conference Location

  • United States