Journal of Applied Physiology, Vol 57, Issue 4 1039-1044, Copyright © 1984 by American Physiological Society
Pressure effects and uptake of platelet-activating factor in isolated rat lung
J. Lichey, T. Friedrich, J. Franke, S. Nigam, M. Priesnitz and K. Oeff
The aim of this study was, first, to examine pressure effects of
platelet-activating factor (PAF) on pulmonary vasculature and bronchi in
isolated perfused and ventilated rat lungs and, second, to investigate
pulmonary uptake of tritium-labeled PAF injected into the pulmonary artery.
Four different perfusates were used: Krebs-Ringer solution (KRS) and KRS
with 0.2, 2.0, and 4% albumin. In the KRS, perfusion and inflation pressure
increased by 100 and 47%, respectively, after 100 micrograms PAF. By
increasing the albumin concentration, the pressure effects were reduced
significantly (P less than 0.01). These changes were paralleled by
increasing tritium outflow rates (15.9 +/- 3.6, 49.7 +/- 12.5, 78.3 +/-
8.7, 87.8 +/- 2.6%, respectively). Comparable changes in tritium outflow
rates (19.2 +/- 3.9, 38.2 +/- 7.2%) occurred when tracer amounts of labeled
PAF were injected, but, in KRS with 2.0 and 4.0% albumin, tritium outflow
was significantly lower (52.8 +/- 8.0 and 60.8 +/- 11.8%, respectively).
Pressure effects are related to extraction rates. Both pressure effects and
extraction rates depend on binding to the albumin in the perfusion medium
used. PAF might act on smooth muscle tissue of the pulmonary vasculature.
Inflation pressure increases are probably due to concomitant occurrence of
edema.
