Fig. 4.

HO exposure decreased SPA and SPC, but not SPB and SPD, mRNA levels in TREK-1/TREK-2/TRAAK-deficient lungs. A and B: decreased SPA and SPC mRNA expression, respectively, in triple KO lungs after 72-h HO exposure compared with WT control lungs. MVL alone did not affect SPA or SPC mRNA levels in either mouse type, whereas the combination of HO + MVL decreased SPA and SPC mRNA levels in both WT control and triple KO lungs. In contrast, SPB (C) and SPD (D) mRNA levels were not affected by the above conditions. Data were normalized to the mRNA expression level of each surfactant type in untreated WT control lungs (n = 4–5 mice per group). E, F, and G: representative Western Blot experiments of nuclear factor-1 (NF-1), NKX2.1, and c-jun protein expression in mouse lung homogenates of RA- or HO-treated mice. For a specific treatment condition, tissue lysates from WT control and triple KO lungs were run on the same gel to allow for comparison of protein expression levels between the 2 groups. H, I, and J: semiquantitative densitometry analysis of normalized NF-1, NKX2.1, and c-jun protein expression levels, respectively (n = 4–5 mice per group; *comparison of WT control and triple KO mice within 1 treatment group); #compared with untreated mice; ^compared with untreated triple KO mice.