Alveolar lining layer liquid is thin and continuous low-temperature
scanning electron microscopy of subpleural rat lung.
Bastacky, Jacob, Charles Y. C. Lee, Jon Goerke, Homayoon Koushafar,
Deborah Yager, Leah Kenaga, Terence P. Speed, Ya Chen, and John A.
Clements.
Life Sciences Division, Lawrence Berkeley Laboratory, University of
California, Berkeley, California 94720, Cardiovascular Research
Institute and Department of Physiology, University of California, San
Francisco, California 94143, Department of Statistics, University of
California, Berkeley, California 94720, Integrated Microscopy
Resource, University of Wisconsin, Madison, Wisconsin 53706,
Cardiovascular Research Institute and Department of Pediatrics,
University of California, San Francisco, California 94143
APStracts 2:0128A, 1995.
The low-temperature electron microscope, which preserves aqueous
structures as solid water at liquid nitrogen temperature, was used to
image the alveolar lining layer, including surfactant and its aqueous
subphase, of air-filled lungs frozen in anesthetized rats at 15 cm
H2O transpulmonary pressure. Lining layer thickness was measured on
crossfractures of walls of the outermost subpleural alveoli which
could be solidified with metal mirror cryofixation at rates
sufficient to limit ice crystal growth to 10 nm and prevent
appreciable water movement. The thickness of the liquid layer
averaged 0.14 [mu]m over relatively flat portions of alveolar walls;
0.89 [mu]m at alveolar wall junctions, and 0.09 [mu]m over protruding
features (9 rats, 20 walls, 16 junctions, 146 areas); for an area
-weighted average thickness of 0.2 [mu]m. The alveolar lining layer
appears continuous, submerging epithelial cell microvilli and
intercellular junctional ridges; varies from a few nanometers to
several micrometers in thickness; and serves to smooth the alveolar
air-liquid interface in lung inflated to zone 1 or 2 conditions.
Received 19 April 1993; accepted in final form 8 February 1995.
APS Manuscript Number A339-3.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 4 April 1995.