Effects of in vitro ozone exposure on peroxidative damage, membrane leakage, and taurine content of rat alveolar macrophages

Abstract

Rat alveolar macrophages (AM) were isolated by pulmonary lavage, allowed to adhere to a tissue culture flask, and then exposed to 0.45 ± 0.05 ppm ozone. After exposures ranging from 0 to 60 min, the medium was decanted and cells were harvested. Cells were assayed for oxidant damage and media analyzed for leakage of intracellular components. Increasing length of exposure to ozone resulted in a decreased number of adherent AM and decreased cell viability. Resting and zymosan-stimulated chemiluminescence increased immediately after ozone exposure and reached a maximum at 15–30 min, then declined to initial levels after 60 min of ozone exposure. Lipid peroxidation and leakage of protein and K + ions increased with increasing length of exposure to ozone, while leakage of reduced and oxidized glutathione increased through 30 min, then declined (reduced) or leveled off (oxidized). Activity of the Na + K + ATPase decreased with time while intracellular taurine concentration exhibited an initial rise, peaked at 30 min, and then returned to the untreated level. Leakage of taurine into the medium increased with time of exposure, suggesting that exposure of AM to ozone results in a shift from bound to free intracellular taurine. These data indicate that in vitro exposure of AM to ozone results in a time-dependent alteration of cell function, membrane integrity, and viability.