Journal of Applied Physiology, Vol 50, Issue 6 1358-1361, Copyright © 1981 by American Physiological Society
Lung fluid and protein exchange in the acute sheep preparation
F. L. Minnear, P. S. Barie and A. B. Malik
We examined the effect of left atrial hypertension on lung fluid and
protein exchange in acutely prepared anesthetized sheep. The results were
compared with those reported by Erdmann jet al. (Circ. Res. 37:271-284,
1975) in chronically instrumented conscious sheep. Animals were
anesthetized with halothane and efferent duct of the caudal mediastinal
node was cannulated. Pulmonary microvascular pressure (Pmv) was elevated by
raising left atrial pressure with a left atrial balloon. For every
elevation in Pmv of 1 cmH2O pulmonary lymph flow (Qlym) increased by 0.5
ml/h. Increasing the Pmv resulted in a linear decrease (p less than 0.05)
in the ratio of lymph to plasma protein concentration as a result of a
significant reduction in lymph protein concentration. Transvascular
clearance of lymph proteins increased by 39% with a doubling of Qlym. The
steady-state changes in pulmonary fluid and protein exchange induced by an
increase in Pmv in acutely prepared anesthetized sheep were the same as
those observed by Erdmann et al. in chronically instrumented unanesthetized
sheep, indicating that the acute preparation is equally reactive to
increase in Pmv and that the lung endothelial permeability is not
increased.
