Figure 2.

Exposure to O₃ induces a dose- and time-dependent increase in the cytosolic E_GSH in airway epithelial cells. BEAS-2B cells expressing cytosolic roGFP2 were exposed to clean air for 5 min followed by a 0 (air control), 0.15, 0.25, or 0.50 ppm O₃ exposure for 35 min in a stage-top exposure system maintained at 37°C, > 90% relative humidity, and 5% CO₂. Shown are ratiometric values (404/488) calculated from the fluorescence intensity emitted at 510 nm induced by sequential excitation at 404 and 488 nm, plotted relative to the 5-min baseline. Addition of 0.1 mM H₂O₂ at the end of the O₃ exposure produced a maximal response, which was fully reversible with the addition of 10 mM DTT. The data shown were derived from three or more separate experiments monitoring seven or more cells in real time throughout the exposure period.