Fig. 5.

Chloride channel blockers relax an established ACh contraction in human airway smooth muscle. A: representative tracings of tension recordings of human airway smooth muscle (ASM) strips contracted with an ACh EC₅₀ dose. Treatment with compound 13 100 μM or compound 13 in combination with bumetanide 10 μM showed significant relaxation within 30 min, whereas treatment with vehicle or bumetanide 10 μM alone showed no relaxation. B: compound 1 or 13 alone (45.4% ± 6.3, 52.5% ± 8.1) and in combination with bumetanide (8.2% ± 11.1, 41.1% ± 6.7) relaxed an ACh contraction, whereas vehicle or bumetanide treatment alone failed to relax an ACh contraction (calculated as percent of remaining ACh EC₅₀ contraction at 30 min). *P < 0.05, **P < 0.001, ***P < 0.001 compared with vehicle; #P < 0.05 compared with compound 1 alone; n = 8–13.