Effects of hyperoncotic albumin on endothelial barrier properties of rat lung
Qiao, R.L.; Ying, X.; Bhattacharya, J.
American Journal of Physiology 265(1 Pt 2): H198-H204
1993
ISSN/ISBN: 0002-9513 PMID: 7688190 Document Number: 422235
We have determined the effect of concentrated albumin on lung endothelial hydraulic conductivity (L-p) 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 cmH-2O) and stopped blood flow, we viewed subpleural venules (diameter, 20 mu-m) 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 L-p for 4 g/dl albumin. In venules that were previously microinfused for 6 min with 4 g/dl albumin, L-p for 4 g/dl albumin did not differ from that of noninfused controls (5.4 +- 0.8 times 10-7 ml cntdot cm-2 cntdot s-1 cntdot cmH-20-1). However, after a similar microinfusion of 6 g/dl albumin, the L-p immediately increased more than two times above baseline (P lt 0.01) but returned to baseline after 15 min. L-p 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.