Tracheal CFTR assay by Ussing Chamber measurement

Chloride ion transport by CFTR channels in rat tracheal explants was estimated in short-circuit current (Isc) units with modified Ussing chambers (Physiologic Instruments, San Diego, CA) under voltage clamp conditions as previously reported [^{6, 7}]. Rat tracheal segments were bathed in identical Ringer’s solution with 95% O₂: 5% CO₂ before sequentially adding apical Amiloride (100μM), apical low chloride Ringers, apical and basal forskolin (20μM), and apical CFTR-inh172 (10μM) (cells) or GlyH101 (10 μM) (trachea). Acquire and Analyze software was used to collect Ussing Chamber data monitoring epithelial ion transport Isc changes upon adding pharmacologic agents known to modulate CFTR activity.