Figure 5.

CF animals have impaired airway mucociliary clearance (MCC) and age-dependent increases in epithelial Na⁺ channel (ENaC) activity. (A) Time-lapse fluorescent photomicrographs of the tracheal MCC assay. The origin of fluorescent bead placement is marked by the arrows, and the distal and proximal ends of each tracheal segment are on the left and right of each photomicrograph, respectively. (B) Quantified MCC rates for seven CF and non-CF matched pairs at 3–8 months of age. *CF animal that was killed due to a rectal prolapse with more mild lung disease. ^†A pair in which the CF animal was found dead in the cage at roughly 3 hours postmortem; MCC on the non-CF animal in this pair was performed at 3 hours after killing to control postmortem influences on MCC. Differences between MCC rates between genotypes were determined using a paired two-way Student’s t test with P value given in the figure. (C) Fold difference (± SEM) in MCC rates between non-CF and CF animals (n = 7). (D) Ussing chamber short-circuit current analysis (I_SC) of tracheal tissue from CF and non-CF animals older than 3 months of age. I_SC was measured after the sequential addition of amiloride (Amil), 4,4′-diisothiocyano-2,2′-stilbene disulphonic acid (DIDS), 1-methyl-3-isobutylxanthine/forskolin (IF), N-(2-Naphthalenyl)-((3,5-dibromo-2,4-dihydroxyphenyl)methylene)glycine hydrazide (GlyH101; GlyH), and bumetanide (Bumet). Quantification of the change in I_SC for each of the indicated drugs is shown (mean ± SEM from n = 7 animals of each genotype). At least two independent tissue samples were evaluated for each animal and the average ∆I_SC for each animal/condition used to calculate the SEM. Significant differences between genotypes by two-tailed Student’s t test are marked (**P < 0.005, *P < 0.05). On average, amiloride-sensitive I_SC was not significantly different between genotypes (P = 0.0654). However, there was a significant age-dependent increase in amiloride-sensitive currents in CF, but not in non-CF, animals (CF, P = 0.0009; non-CF, P = 0.7637 [by Spearman correlation]; see Figure E3). (E) Bacterial titers of lung homogenates from three non-CF and 11 CF animals. (F) Quantification of bacteria taxa found in lung homogenates from 10 CF animals using matrix-assisted laser desorption–ionization time-of-flight mass spectrometry (MALDI-TOF MS) fingerprinting. Only genera are shown; for complete genus and species, see Figure E4A.