Ultrastructural observations on experimental shock lung
Respiratory Distress Syndrome, Adult
Intercellular junctions in the alveolar epithelium and in the capillary endothelium in the dogs after hemorrhagic shock (mean BP 40 mm Hg for 3 hours) and from control dogs were observed in the electron microscope using the freeze-fracture and etch technique. Following shock, tight junctions (zonulae occludentes) in the alveolar epithelium which were well developed with may strands in control animals showed alterations in substructure. Some desintegration and disappearance of junctional strands in "focal" regions were occasionally observed in the endothelium as well. The increased pulmonary capillary permeability observed physiologically after hemorrhagic shock may be explained by such alterations of endothelial zonulae occludentes.