Volume and protein concentration of epithelial lining liquid in
perfused in situ postnatal sheep lungs.
Stephens, R. H., A. R. Benjamin, and D. V. Walters.
Department of Child Health, St. George's Hospital Medical School,
Cranmer Terrace, London SW17 0RE, UK, Tel. 0181 725 3925,. Fax. 0181
725 2858
APStracts 3:0038A, 1996.
Previous methods of estimating the volume of epithelial lining liquid
(ELL) in the air-filled lung may be said to have suffered from some
theoretical and practical deficiencies. To estimate this volume (VE)
more accurately, a known amount of artificial lung liquid (LL)
containing the impermeant tracer [125I]-albumin was instilled
intraluminally in 56 in situ perfused postnatal sheep lungs (aged 36
hours to 12 weeks) and the rate of change of LL volume was measured
by changes in tracer concentration. Linear regression of LL volume
against time allowed calculation of VE at the time of instillation;
it was found to be 0.37 +/- 0.15 ml.(kg body weight)-1, which is
equivalent to a film of 0.15 +/- 0.06 [mu]m mean depth. The median
ELL protein concentration was 36.8 mg.(ml ELL)-1, ie. 0.60 times the
plasma concentration, which agrees with previously published
estimates, and which is similar to interstitial protein
concentration. We conclude that the ELL volume is very small and that
there is unlikely to be a protein osmotic gradient across the
pulmonary epithelium.
Received 21 March 1995; accepted in final form 3 January 1996.
APS Manuscript Number A309-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 25 January 96