SOD1 mRNA and protein expression. RT-PCR: (A) SOD1 mRNA was similar in FA controls between both lung compartment and age. (B) Neonates had decreased SOD1 mRNA expression in PFP48. (C) Adults had increased airway SOD1 mRNA at PFP48. Data are presented as mean+SEM (n=5-7 rats/group, in each compartment), ‡ significantly different compared to FA in the same compartment. Western blotting: (D) Representative SOD1 blot with actin. (E) Neonatal whole lung SOD1 protein expression was unchanged post exposure. (F) Adult whole lung SOD1 trended upwards at PFP48, but was statistically insignificant. Data are presented as mean+SEM (n=6 rats/group). (G-J) SOD1immunohistochemical detection of SOD1 protein (n=6 rats/group) in neonatal lung tissue was unchanged post exposure. Contrastingly, intense airway and parenchymal SOD1 protein expression was observed in adult PFP48. Scale bars are 50 μm.