Pulmonary capillary diameters and recruitment characteristics in
subpleural and interior networks.
Short, Amy C., Michael L. Montoya, Sarah A. Gebb, Robert G. Presson,
Jr., Wiltz W. Wagner, Jr., and Ronald L. Capen.
Biology Department, The Colorado College, Colorado Springs, CO
80903 and Departments of Anesthesia, Physiology/Biophysics, and
Pediatrics, Indiana University School of Medicine, Indianapolis, IN
46202
APStracts 2:0544A, 1995.
In vivo microscopic observations of pulmonary capillaries are limited
to subpleural networks which are less dense than interior networks.
In addition to the density difference, subpleural and interior
capillaries diameters may differ, although there are conflicting data
on this point. We measured the diameters of subpleural and interior
capillaries in rats and dogs. Subpleural diameters were 30% larger in
rats and 20% larger in dogs. To determine whether density and
diameter differences affected capillary recruitment characteristics
of the two networks, we measured subpleural and interior recruitment
by counting the number of red blood cells/10 [mu]m of alveolar wall
in histologic cross sections of rapidly frozen rat lungs. Lung
inflation pressures of 4, 12, and 25 cmH2O created a wide range of
capillary recruitment in different groups of animals. Red blood cell
counts for interior and subpleural capillaries moved in parallel and
progressively increased as inflation pressures were reduced. These
data demon strate that recruitment in subpleural capillaries
accurately reflect recruitment in interior capillaries and validates
in vivo observations of subpleural capillaries in recruitment
studies.
Received 26 July 1995; accepted in final form 6 December 1995.
APS Manuscript Number A819-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 December 95