Electron Microscopic Alterations at the Alveolar Level in Pulmonary Edema

Abstract

The electron microscopic alterations of the alveolar septum in advanced hemodynamin and alloxan-induced pulmonary edema were compared. Pulmonary edema was produced in anesthetized dogs by means of increased lefy atrial pressure and hemodilution and by allocan administration. Sections of pulmonary tissue from these dogs and similarly anesthetized controls were processed for and examined by light and electron microscopy. In the hemodynamic form of edema the interstitial fluid collects only in the collagen-containing portions of the septum. The endothelium, epithelium, their respective basement membranes and large portions of the air-blood barrier are unaffected. Alloxaninduced edema, in contrast, is characterized by degeneration of both endothelium and epithelium and by the appearance of fibrin within the alveoli. The hemodynamic type of pulmonary edema appears to result from an accentuation of the normal process of fluid exchange within the lung. Allocan-induced edema, on the other hand, is a pathologic process. The functional implications of these results are discussed.

Morphological Characteristics of a Rat Model of Reexpansion Pulmonary Edema

“…In addition, the alveolar wall exhibited fissures perpendicular to its several layers, although the integrity of these layers was otherwise maintained ( Figure 5). These changes in pulmonary tissue structure completely differ from those reported by Cottrell et al [11] for other edema types (which were caused by alloxan or static hydraulic lung pressure). This discrepancy suggests that although pulmonary edemas might appear to have similar features, electron microscopic observation may yield very different findings, due to differences in pathogenesis.…”

“…The present in vivo microscopic observations showed slower blood flow in capillaries of some areas used electron microscopic observation to investigate pulmonary edema induced by causes other than lung reexpansion. Cottrell et al [11] used electron microscopy to observe edema caused by static hydraulic lung pressure and reported that such edema only developed on alveolar walls in areas where collagen-fiber tissues were present (with no changes at the blood-air barrier). The same group analyzed electron microscopic images of alloxan-induced edema, which showed clasmatosis in the epithelium and endothelium but no edema in the alveolar septum [11].…”

“…Cottrell et al [11] used electron microscopy to observe edema caused by static hydraulic lung pressure and reported that such edema only developed on alveolar walls in areas where collagen-fiber tissues were present (with no changes at the blood-air barrier). The same group analyzed electron microscopic images of alloxan-induced edema, which showed clasmatosis in the epithelium and endothelium but no edema in the alveolar septum [11]. The present experimental group exhibited almost no changes in vascular endothelial cells or in the distance between cells (Figures 3 and 4), but pores measuring 0.01-0.1 μm in diameter were present in alveolar epithelial cells.…”

Biochemical and Morphological Alterations in Xylazine-Induced Pulmonary Edema*,†

“…Endothelial injury is evident as early as 0.5 hr after administration of xylazine and becomes more pronounced by 12 hr. These changes are similar to those caused by known edemagenic agents such as alloxan and a-naphthylthiourea, which cause increased permeability PE (11,12).…”

Increased Sheep Lung Vascular Permeability Caused by Pseudomonas Bacteremia

“…The increase in lymph flow in the Pseudomonas experiments was 10-fold or less and lymph-plasma globulin ratios tended to fall from base line. It has been suggested that for some increased permeability states, the diameter of the larger pores simply increases (26,38). As illustrated by Fig.…”