LUNG LESIONS IN EXPERIMENTAL HYDROSTATIC PULMONARY-EDEMA - AN ELECTRON-MICROSCOPIC AND MORPHOMETRIC STUDY

Distinct barrier lesions and an apical-basal distribution of alveolar edema fluid in either moderate or high elevated pressure edema lungs h ave been found in previous studies. In the present study, quantitative measurements were obtained by using electron microscopy and morphomet ry of extravascular lung water and barrier lesions, on the relations b etween interstitial and alveolar edema fluid as well as between extrav ascular lung water and barrier lesions. The study further addressed th e question of whether 6% bovine serum albumin (BSA) perfusion could in duce lung ultrastructure alterations. It was found that interstitial f luid distribution is similar to that of alveolar edema fluid. Epitheli al blebs are also distributed with an apical-basal gradient, and are a lways submerged in alveolar edema fluid. Perfusion with 6% bovine seru m albumin, does not induce any lung ultrastructure alterations. The re sults indicate that endothelium and epithelium play a different role i n controlling fluid movement between capillary and extravascular space s and thus in preventing the formation of interstitial and alveolar ed ema. Because the interaction of cells and tissue must be taken into ac count, simple physiological models of pulmonary fluid exchange may not be adequate to explain pulmonary edema formation.