title: Effects of exposure to NO2 on dome formation in alveolar epithelial cell monolayers.
abstract: Primary cultured monolayers of rat Type II pneumocytes were used to investigate the effects of NO2 on alveolar epithelial barrier properties. Such monlayers form fluid-filled domes which are thought to result from active solute transport from medium to substratum, with water following passively. Using dome formation as a transport marker, 5-day-old cultures were directly exposed to 30 ppm NO2 in 5% CO2/air at 25 degrees C by cyclically tilting culture plates from side to side such that both halves of the monolayer were exposed during each cycle. Exposures consisted of 10 cycles of 4 min each (2 min per side), for a cell exposure time of 20 min. Control plates were simultaneously exposed to 5% CO2/air under identical conditions. Twenty-four hours after exposure, NO2-exposed monolayers exhibited significant decreases in dome density and individual dome volume as compared to controls. By 48 hr postexposure, differences between NO2-exposed and control values were less but remained significant. Control monolayers were essentially unaffected by exposure to 5% CO2/air. These results show that short-term sublethal exposures to NO2 produce a decrease in dome formation in Type II alveolar epithelial cell monolayers. This finding is most likely due to a decrease in the active transepithelial sodium transport rate and/or an increase in the permeability of cell membranes or tight junctions.
mesh_terms: D000818:Animals; D001826:Body Fluids / Q000378:metabolism; D003584:Cytological Techniques; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009585:Nitrogen Dioxide / Q000494:pharmacology*; D011650:Pulmonary Alveoli / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
chemical_list: D009585:Nitrogen Dioxide