Estimated functional diameter of alveolar septal microvessels in
zone i .
Conhaim, Robert L., and Lance A. Rodenkirch.
Department of Surgery, University of Wisconsin-Madison, Madison,
Wisconsin
APStracts 3:0095H, 1996.
To estimate the functional diameter of alveolar septal microvessels in
zone 1, we perfused isolated rat lungs with fluorescent latex
particles of specific diameters (0.24, 0.49, 1.05, 4.0 [mu]m) at
pulmonary artery pressures (Ppulm art) that were either 5 or 10 cmH2O
less than the air inflation pressure (Pinflat, 25 cmH2O). We then
prepared samples for histology. Using a confocal, laser-scanning
fluorescence microscope, we measured latex particle densities within
the septal plane that ranged from 0.08+/-0.04 particles per [mu]m2
(0.24 [mu]m diameter particles) to 0.02+/-0.01 particles per [mu]m2
(1.05 [mu]m diameter particles). We found that 4.0 [mu]m diameter
particles were not able to enter septa at all. Latex particles were
not present in all alveoli. When Ppulm art was 5 cmH2O less than
Pinflat, 32+/-6% of septa contained 0.24 [mu]m diameter particles,
but when Ppulm art was 10 cm less than Pinflat, 5+/-6% of septa
contained these particles. Percentages were smaller for larger
particles. We conclude that when Ppulm art is both 5 and 10 cmH2O
less than Pinflat, the functional diameter of accessible septal
microvessels is greater than 1.05 but less than 4.0 [mu]m.
Furthermore, the number of accessible septa decreases as the
difference between Ppulm art and Pinflat widens.
Received 20 November 1995; accepted in final form 22 February
1996.
APS Manuscript Number H1088-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 20 March 96