Fig. 4. (A ) Determination of NF-κB DNA binding activity. Nuclear elements were extracted from whole lung, previously exposed to acid for 0.5, 1, 2, 4, 6, and 8 h. Electrophoretic mobility shift assay for NF-κB was performed. Specificity for NF-κB was shown by using competitive unlabeled NF-κB oligonucleotides and a p65 antibody. White bar  represents values from control animals, and black bars  represent values from animals after HCl stimulation. Densitometry was performed, and results are expressed as percentage of values obtained from PBS animals (100%). Values are means ± SEM from five different assays. The blot  represents one of five experiments. (B ) Determination of whole lung mRNA of IκBα. Whole lung RNA was extracted, and reverse transcriptase–polymerase chain reaction was performed. Equal loading was shown with 18S bands. White bars  represent values from control animals, and black bars  represent values from animals after HCl stimulation. Densitometry was performed, and results are expressed as percentage of values obtained from PBS animals (100%). Values are means ± SEM from five different assays. The blot represents one of five experiments.