Figure 6: Effects of repeated O2, IR and combined challenge on Nitrotyrosine formation, during the late phase post termination of the challenge exposure. Separate cohorts of mice were exposed to 100% O2 for 8 hours only (O2), 0.25 Gy total body ionizing gamma irradiation (IR) only, or a double-hit combination of both challenges (O2+IR) followed by intermittent normoxia (21% pO2) for repeated cycles 3 times a week for 4 weeks. Mice were sacrificed at 20 weeks (chronic). Panels A-D Representative sections from paraffin lung sections stained for nitrotyrosine (brown staining) from untreated (A), O2 (B), IR (C) and O2+IR (D) animals. Sections were counterstained with crystal blue. Panel E Representative western blot validation of NT formation in lung homogenates from the same mouse cohorts as above. Panel F Densitometric analysis with beta actin normalization of the combined levels of all 3 major NT bands for each cohort.
Data is represented as mean fold change from untreated at each respective time point ± SEM. Letter a indicates p< 0.05 for all challenges vs. untreated at each respective time point.