Figure 5

Hyperoxia exposure alters location and expression of ZO-1 and occludin in alveolar epithelial. Immunostaining and western blot analysis were performed to identify alteration in location and expression of ZO-1 and occludin in alveolar epithelial. A continuous line along the membrane and diffuse in the cytoplasm staining of ZO-1 and occludin was shown in the alveolar epithelium of control rats (A, D). After 3 and 5 days, hyperoxia exposure induced partial breakdown of membrane staining and decreased cytoplasm staining of ZO-1 in the alveolar epithelium (B). The staining intensity of ZO-1 and occludin was dramatically reduced in lung tissues from rats which were exposed to hyperoxia for 7 days (C, E). Bars represent 50 μm. After 7 days of hyperoxia exposure, the expression of ZO-1 and occludin dramatically declined and was virtually undetectable examined by Western blotting. β-actin immunoreactive bands were used to demonstrate equal loading (F, H). Densitometric quantification of ZO-1 and occludin protein levels was expressed as fold increase compared with normoxia for 1 day group (set as 1) (G, I). Values are presented as means ± SD; *P < 0.05, ** P < 0.01 versus normoxia group. The results shown are representative of experiments that were repeated 4 times.