Figure 5.

HTS treatments stimulate active ASL production by airway epithelia. (A) Treatment with the CFTR blocker CFTRinh172 (100 µM) reduced HTS-triggered ASL height increase, and treatment with CFTRinh172, bumetanide (100 µM), and niflumic acid (100 µM) in HCO₃⁻-free saline solution bath reduced HTS-triggered ASL height increase even further (HTS, n = 45 beads from 15 tracheas; HTS + 172, n = 59 beads from 12 tracheas; HTS + Bumet + NA + 172 + HCO₃⁻-free, n = 24 beads from 7 tracheas). (B) In ITS-treated preparations incubation with the ion transport blocker cocktail (CFTRinh172, bumetanide, and niflumic acid in HCO₃⁻-free bath) had a similar effect as CFTRinh172 alone (ITS, n = 49 beads from 14 tracheas; ITS + 172, n = 29 beads from 8 tracheas; ITS + Bumet + NA + 172 + HCO₃⁻-free, n = 18 beads from 7 tracheas). (C) Approximately 50% of the ASL produced by HTS in airways without CFTR function is the result of the osmotic effect. After blocking all ion transport with CFTRinh172, bumetanide, and niflumic acid in HCO₃⁻-free saline, HTS produced ~50% less ASL secretion than that produced by preparations incubated with CFTRinh172 alone (HTS + 172, n = 59 beads from 12 tracheas; HTS + Bumet + NA + 172 + HCO₃⁻-free, n = 24 beads from 7 tracheas; ITS + Bumet + NA + 172 + HCO₃⁻-free, n = 18 beads from 7 tracheas). Data are presented as mean ± SEM and values at 18 min were analyzed with ANOVA and Tukey’s multiple comparison test. Data sets labeled with different letters differ significantly, p < 0.05.