Fig. 2.

Effects of hyperoxia exposure on the expression and distribution of ZO-1, occludin, and claudin-4 in the in vitro pulmonary epithelial barrier model. Alveolar cell monolayers were exposed to normoxia (N) (21 % O₂/5 % CO₂) or hyperoxia (H) (85 % O₂/5 % CO₂) for 0, 24, 48, and 72 h. mRNA (a, b, c, d), protein (e, f, g, h), and distribution (i) of ZO-1, occludin, and claudin-4 were determined using RT-PCR, Western blot, and immunofluorescence staining, respectively. (i) Green indicates ZO-1 and occludin, and red indicates claudin-4 (800× magnification). Values are represented as means ± SD, ^## P < 0.01 for comparison between the H and N groups, ^* P < 0.05 and ^** P < 0.01 for comparison between different time points in the H group