Figure 5. Luminal Cl⁻ removal abolished the augmentation of FSK-induced by F508del-CFTR membrane expression in duodenal mucosa.

Replacement of Cl⁻ in the luminal bath by gluconate caused a slight decrease in the basal in each genotype (A), and reduced the in the F508del mucosa to the values seen in the CFTR KO mucosa (A and C). These data suggest that FSK (10⁻⁵ m) elicits a robust independently of luminal Cl⁻/HCO₃⁻ exchange in WT mucosa, whereas the augmentation of FSK-induced by F508del expression requires luminal Cl⁻/HCO₃⁻ exchange. Basal I_sc (B) and R_t (E) increased significantly in all three genotypes after Cl⁻ replacement by gluconate, and the I_sc response to FSK (D) was not different from that seen in the presence of luminal Cl⁻ (Fig. 2). ***P < 0.001, *P < 0.05; ns, no statistical difference; n= 5–9.