Fig. 7. Functional restoration of F508-del. Ussing chamber experiments were performed to evaluate CFTR-mediated Cl^- secretion in parental CFBE41o^- cells or cells stably expressing F508-del (F508del) or wt CFTR after treatment with either ∆27-264- or ∆264-containing AAV2/1 virus. The data show that transcomplementation rescues the function of wt CFTR (A), F508-del (B) and parental cells (C). Original short-circuit current recordings in untreated cells (black line) or after incubation of ∆27-264-, or ∆264- -containing AAV2/1 virus (10 µl, 7 days) in cells kept at 37°C. Corresponding ∆Isc summary data are normalized to untreated CFBE41o^- cells. Data are expressed as the CFTR_inh172-sensitive short-circuit current (∆Isc), calculated by subtracting the Isc after CFTR_inh172 treatment from the peak forskolin-genistein-stimulated Isc. Normalized responses calculated by normalizing the ∆Isc response to the untreated condition. Statistical significance is indicated as follows: ns, no significant difference; *P<0.05; **P<0.01; ***P<0.001 (n=4-5 for each condition) when compared with the control condition. Amiloride (100 µM) was present during the whole duration of each experiment to avoid interference by ENaC-mediated Na⁺ currents.