FIGURE 7.

The TMEM16A antagonists, benzbromarone, niclosamide, and Compound 4 fully relax mouse tracheal rings but have a slow onset of action. The average concentration-response relationship (A–C) and raw wire myograph recordings of force changes over time are shown for benzbromarone (A,D), niclosamide (B,E), and Compound 4 (C,F) for relaxation of mouse tracheal rings pre-contracted with an EC₇₅ concentration of carbachol. The lipophilic compounds benzbromarone (XLogP3 = 5.66), niclosamide (XLogP3 = 5.32), and Cpd 4 (XLogP3 = 4.63) took an extended period of time to achieve steady-state relaxation of the tissue but had efficacy similar to theophylline in fully relaxing the mouse airways. At a 1 μM dose, benzbromarone (D) exhibited a slow onset of action taking between 40–60 min to achieve steady-state relaxation of the tissue, while niclosamide took between 17–35 min at the same dose (E). Cpd 4 also had a slow onset of action taking between 25–45 min at 316 nM to achieve steady-state relaxation (F). In contrast the hydrophilic β-agonist isoproterenol (XLogP3 = –3.49), while only partially relaxing airway rings pre-contracted with an EC₇₅ level of carbachol, acted quickly taking just 2–4 min to bronchodilate the tissue (Supplementary Figure 39). To enable direct comparison of the activity of the molecules, compounds were run in parallel on the same day in separate chambers of the wire myograph. Theophylline was routinely added at the end of the recording to define full bronchodilation and calculate percent relaxation of the tissue. The results shown are from 3 to 5 separate experiments. Mean ± SEM.