Figure 3.

CFFT‐004 corrects and potentiates F508del‐CFTR channel gating. (A–D) Representative single‐channel records of wild‐type and F508del‐CFTR in excised inside‐out membrane patches from BHK cells under the indicated experimental conditions. ATP (1 mM) and PKA (75 nM) were continuously present in the intracellular solution. When tested as correctors (cor) or dual‐acting small molecules (cor‐pot), CFFT‐004 (CF4) and C18 were used at 5 μM and either incubated with cells for 24 h at 37°C or added acutely to the intracellular solution. Prior to commencing channel recordings, cells incubated with CFFT‐004 and C18 were thoroughly washed to remove any residual small molecules from the extracellular solution; the maximum period cells were left in drug‐free solution before study did not exceed 30 min. In (C) and (D), the recordings are from the same membrane patches before and after testing CFFT‐004 and C18 as potentiators. Dotted lines indicate the closed channel state, and downward deflections correspond to channel openings. Unless otherwise indicated in this and other figures, membrane patches were voltage‐clamped at −50 mV, there was a large Cl⁻ concentration gradient across the membrane ([Cl⁻]_int, 147 mM; [Cl⁻]_ext, 10 mM) and temperature was 37°C. (E–G) P_o, MBD and IBI of F508del‐CFTR for the indicated conditions. Data are means ± SEM (WT, n = 5; F508del 27°C rescue, n = 18; F508del CFFT‐004 correction, n = 6; F508del CFFT‐004 dual‐action, n = 6; F508del C18 correction, n = 6; F508del C18 dual‐action, n = 6); *, P < 0.05 versus WT‐CFTR; †, P < 0.05 versus F508del‐CFTR 27 °C rescue; ‡, P < 0.05 versus CFFT‐004 correction.