Incorporation of biotinylated SP-A into rat lung surfactant layer, type II cells, and clara cells.

Journal Article (Journal Article)

The goal of this study was to compare the functions of Clara and type II cells during alveolar clearance and recycling of surfactant protein (SP) A, a secretory product of both cell types. We examined the incorporation of instilled biotinylated SP-A (bSP-A) into rat lung type II and Clara cells as a measure of clearance and recycling of the protein. Ultrastructural localization of bSP-A was accomplished by an electron-microscopic immunogold technique at 7, 30, and 120 min after intratracheal instillation. Localization of bSP-A was quantitatively evaluated within extracellular surfactant components (lipid-rich forms: myelin figures, vesicles, and tubular myelin; and lipid-poor hypophase) and in compartments of type II and Clara cells. bSP-A was incorporated into myelinic and vesicular forms of extracellular surfactant, but tubular myelin and hypophase had little bSP-A. Lamellar bodies of type II cells demonstrated a significant time-dependent increase in their incorporation of bSP-A. There was a concentration of bSP-A in the secretory granules and mitochondria of Clara cells, but no Clara cell compartment showed a pattern of time-dependent change in immunolabeling. Our immunolabeling data demonstrated a time-dependent movement of exogenous SP-A from extracellular components into type II cells and their secretory granules. Clara cells did not demonstrate a time-dependent incorporation of bSP-A into their secretory granules during the period of this study. If Clara cells recycle SP-A, they must reach a steady state very quickly or very slowly.

Full Text

Duke Authors

Cited Authors

  • Savov, J; Wright, JR; Young, SL

Published Date

  • July 2000

Published In

Volume / Issue

  • 279 / 1

Start / End Page

  • L118 - L126

PubMed ID

  • 10893210

International Standard Serial Number (ISSN)

  • 1040-0605

Digital Object Identifier (DOI)

  • 10.1152/ajplung.2000.279.1.L118


  • eng

Conference Location

  • United States