Journal of Applied Physiology, Vol 68, Issue 4 1354-1359, Copyright © 1990 by American Physiological Society
Silica directly increases permeability of alveolar epithelial cells
R. K. Merchant, M. W. Peterson and G. W. Hunninghake
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242.
Alveolar epithelial cell injury and increased alveolar-capillary membrane
permeability are important features of acute silicosis. To determine
whether silica particles contribute directly to this increased
permeability, we measured paracellular permeability of rat alveolar
epithelium after exposure to silica, in vitro, using markers of the
extracellular space. Silica (Minusil) markedly increased permeability in a
dose- and time-dependent manner. This was not the result of cytolytic
injury, because lactate dehydrogenase release from monolayers exposed to
silica was not increased. Pretreatment of the silica with serum, charged
dextrans, or aluminum sulfate blocked the increase in permeability.
Scanning electron microscopy demonstrated adherence of the silica to the
surface of the alveolar epithelial cells. Thus silica can directly increase
permeability of alveolar epithelium.
