Morphological changes in isolated perfused dog lungs after acute hydrostatic edema.

Abstract

Morphometric data from stable (nonedematous) isolated dog lungs, perfused with nearly cell-free perfusates, were compared to similar stereological evaluations of isolated dog lungs after induction of severe acute hydrostatic edema. In the edematous lungs, capillary surface and volume densities were substantially increased. Alveolar surface density was also increased. Thicknesses of the endothelial and type I epithelial cellular compartments of the air-blood barrier were unchanged. Thickness of the interstitial compartmemt of the air-blood barrier was substantially increased and this, in turn, caused an overall increase in mean thickness of the barrier. Volume densities of the nonparenchymal connective tissue spaces surrounding the extra-alveolar vessels and airways were also increased. In both the endothelial and type I epithelial cells cytoplasmic volume densities of pinocytotic vesicles were increased. In addition, the number of vesicles opening onto the luminal and albuminal cellular surfaces increased signficantly. Transendothelial vesicular passage may contribute to interstitial edema formation, and transepithelial vesicular transport may contribute to alveolar flooding in isolated perfused dog lungs.