SOD2 mRNA and protein expression. RT-PCR: (A) SOD2 mRNA expression is higher in adults, and highest in the adult parenchyma. (B) No exposure effects on SOD2 mRNA were observed in neonates. (C) Adult SOD2 mRNA was decreased in PFP48. Data are presented as mean+SEM (n=5-7 rats/group, in each compartment), * significantly different compared to neonates in the same compartment, † significantly different compared to airways in the same age, ‡ significantly different compared to FA in the same compartment. Western blotting: (D) Scan of representative SOD2 and actin blots. (E) Neonatal whole lung SOD2 protein expression was unchanged with exposure, and (F) adult whole lung SOD2 protein trended upwards at PFP2, but was statistically insignificant. (G-J) Immunohistochemical localization of SOD2 in lung (n=6 rats/group). SOD2 protein was more abundant in adults compared to neonates, but no exposure specific differences were observed. Scale bar is 50 μm.