Fig. 3.

The presence of ${\mathrm{HCO}}_3^{-}$ increases phosphorylation and sensitizes cystic fibrosis transmembrane conductance regulator (CFTR) to genistein. A, bottom: blot of phosphorylated CFTR from cells incubated in 10 μM adenosine (Ado), 28.5 mM ${\mathrm{HCO}}_3^{-}$ (BR), 28.5 mM ${\mathrm{HCO}}_3^{-}$ + 20 mM ${\mathrm{HSO}}_3^{-}$ (BR + BS), 0 ${\mathrm{HCO}}_3^{-}$ (BF), 0 ${\mathrm{HCO}}_3^{-}$ + 20 mM ${\mathrm{HSO}}_3^{-}$ (BF + BS), or 10 μM forskolin (FSK). A, top: relative CFTR phosphorylation from blot. B: ○, %increase in CFTR phosphorylation after incubation in varying [${\mathrm{HCO}}_3^{-}$] relative to 0 ${\mathrm{HCO}}_3^{-}$; ●, increase in apical Cl⁻ permeability relative to 0 ${\mathrm{HCO}}_3^{-}$. Data points are means ± SE; nos. in parentheses indicate the no. of trials. C: effect of 5 μM genistein (Gen) on ${\mathrm{HCO}}_3^{-}$-activated Cl⁻ permeability in 0.3 mM AMP-CP-treated cells. Breaks in trace indicate periods of wash in Cl⁻-free solution. D: summary data for C. *Significantly different from BF (n = 10, P < 0.05). ^#Increment over BF is significantly greater than the sum of the increased rates over BF due to BF + Gen plus BR (indicated by dashed line in BR + Gen bar) (n = 10, P < 0.05).