Silica directly increases permeability of alveolar epithelial cells.
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.
Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242.
R K
RK
Merchant
M W
MW
Peterson
G W
GW
Hunninghake
D000534:Alum Compounds / Q000494:pharmacology; D000818:Animals; D002463:Cell Membrane Permeability / Q000187:drug effects*; D002478:Cells, Cultured; D003911:Dextrans / Q000378:metabolism / Q000494:pharmacology; D004553:Electric Conductivity; D004848:Epithelium / Q000378:metabolism; D007444:Inulin / Q000378:metabolism; D007700:Kinetics; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008353:Mannitol / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D011650:Pulmonary Alveoli / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012822:Silicon Dioxide / Q000378:metabolism / Q000494:pharmacology*
D000534:Alum Compounds; D003911:Dextrans; C041524:aluminum sulfate; D008353:Mannitol; D012822:Silicon Dioxide; D007444:Inulin; D007770:L-Lactate Dehydrogenase