AJP - Heart and Circulatory Physiology, Vol 265, Issue 1 198-H204, Copyright © 1993 by American Physiological Society
Effects of hyperoncotic albumin on endothelial barrier properties of rat lung
R. L. Qiao, X. Ying and J. Bhattacharya
Department of Medicine, St. Luke's-Roosevelt Hospital Center, College of Physicians and Surgeons, Columbia University, New York, New York 10019.
We have determined the effect of concentrated albumin on lung endothelial
hydraulic conductivity (Lp) by our split-drop technique. We anesthetized 39
rats (2% halothane and pentobarbital sodium, 30 mg/kg ip; Sprague-Dawley,
500 g), then isolated and blood perfused their lungs. At constant inflation
pressure (5 cmH2O) and stopped blood flow, we viewed subpleural venules
(diameter, 20 microns) by microscopy and video. By micropuncture, we first
microinfused a venule for 6 min with albumin that was either isoncotic (4
g/dl) or hyperoncotic (6 g/dl) with respect to rat plasma. In the same
venule we then injected and split an oil drop with 4 g/dl albumin. From the
rates of movement of the split oil drop at different vascular pressures, we
determined Lp for 4 g/dl albumin. In venules that were previously
microinfused for 6 min with 4 g/dl albumin, Lp for 4 g/dl albumin did not
differ from that of noninfused controls (5.4 +/- 0.8 x 10(-7)
ml.cm-2.s-1.cmH2O-1). However, after a similar microinfusion of 6 g/dl
albumin, the Lp immediately increased more than two times above baseline (P
< 0.01) but returned to baseline after 15 min. Lp for 4 g/dl albumin was
not affected by hyperoncotic preinfusions of either neutral dextran or
immunoglobulin G. We conclude that concentrated albumin caused a reversible
increase of the lung endothelial barrier conductivity.
