NF-κB Blockade Reduces the O2-Evoked Rise in Na⁺ Conductance in Fetal Alveolar Cells

Electrophoretic mobility shift assays revealed minimal levels of NF-κB activity in rat distal lung epithelial cells cultured at fetal (23 mmHg) or adult alveolar (100 mmHg) P_O2, but revealed significant activation of this transcription factor in cells exposed to a rise in P_O2 mimicking that experienced at birth. This response was entirely abolished by pretreating cells with 5 mM sulfasalazine (SSA). This shift in P_O2 also evoked a rise in apical Na⁺ conductance (G_Na+) that may underlie the O₂-evoked stimulation of Na⁺ transport seen in these cells. Pretreatment with SSA had no effect upon G_Na+ in cells cultured continually at adult or fetal P_O2 but did inhibit the increase in G_Na+ seen in cells that had experienced the rise in P_O2. O₂-evoked activation of NF-κB may thus mediate the increased Na⁺ transport that occurs when the distal lung epithelial cells are exposed to a physiologically-relevant increase in P_O2.