Journal of Applied Physiology, Vol 56, Issue 3 691-699, Copyright © 1984 by American Physiological Society
Failure of myocardial ischemia to increase pulmonary microvascular permeability in dogs
J. C. Parker, L. Campbell, S. Gilchrist, G. Longenecker and A. E. Taylor
Increased extravascular lung water has been reported following periods of
myocardial ischemia. To determine whether increased pulmonary microvascular
permeability was produced by ischemia, total protein lymph-to-plasma
concentration ratios (CL/CP) were obtained at mechanically increased left
atrial pressures (Pla) before and after ligation of the left anterior
descending coronary artery in dogs. Pulmonary and systemic vascular
pressures and cardiac output were monitored and lymph flow was measured
from an afferent tracheobronchial lymphatic. Osmotic reflection
coefficients (sigma) for total protein were estimated using CL/CP = 1-sigma
at high filtration rates, and permeability-surface area (PSf) products were
fit to the data. The postischemic lung lymph data best fit average values
of sigma = 0.68 and PSf = 0.073 ml X min-1 X 100 g-1 wet weight. There were
no significant differences in lymph protein or water clearances between the
pre- and postischemic increased Pla states or for myocardial ischemia
compared with control values for the experimental preparation. Levels of
6-ketoprostaglandin F1 alpha, a degradation product of prostacyclin,
increased by 10- to 14-fold above preischemic values in pulmonary lymph,
and there was a significant increase in pulmonary vascular resistance
during ischemia. Extravascular lung water was not increased above that
attributed to the increased Pla alone. These data indicate no significant
increase in pulmonary microvascular permeability to plasma proteins during
myocardial ischemia.
