FIGURE 1.

Cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction is caused by cigarette smoke exposure in ferrets. a) Representative nasal potential difference (NPD) tracings of ferrets exposed to whole cigarette smoke or room air via a nose-only exposure system for 6 months. Tracings represent mean potential difference (PD) following perfusion with Ringer’s, amiloride (100 μM), chloride-free forskolin (Zero Cl⁻) (20 μM), forskolin (10 μM) and GlyH101 (20 μM). b) Summary data of ferret NPD for ferrets in air control and smoke-exposed cohorts. Data are shown as mean±SEM. Significance was determined by two-way ANOVA with post hoc Tukey. c–e) The effect of smoke exposure on CFTR function in individual ferrets is shown by quantifying mean change in amiloride-sensitive (c), forskolin-stimulated (d) and GlyH101-inhibited (e) PD (n=7, air control and n=7, cigarette smoke, unpaired t-test). f) Temporal change in CFTR function measured by chloride-free forskolin. Data are shown as mean±SEM. Significance was determined by two-way ANOVA with post hoc Sidak; individual replicates at 6 months are shown in d. g) Representative short-circuit current (Isc) measurements of excised trachea from ferrets exposed to air or cigarette smoke (n=11) and treated with forskolin in the setting of amiloride. h) Mean change in Isc upon treatment with forskolin in tissues representing both experimental ferret groups (n=9, air control and n=11, cigarette smoke, Mann–Whitney U test). i) Representative images of immunoblot analysis of CFTR protein in whole-lung lysates of ferrets exposed to smoke or room air for 6 months. j) Summary of mean relative expression of CFTR normalised to the housekeeping protein tubulin (n=11, air control and n=12, cigarette smoke, unpaired t-test). k) Relative expression of ferret CFTR mRNA is shown for whole-lung lysates with and without smoke exposure (n=8 per group, Mann–Whitney U test). NS: not significant; *: p<0.05; **: p<0.01; ***: p<0.001; ****: p<0.0001.