Figure 1. Seventy-two-hour albuterol exposure reduces stimulated apical CFTR activity in wtCFTR⁺ CFBE41o- cells and primary human airway epithelial cells (HAECs).

wtCFTR⁺ CFBE41o- cells and HAECs were exposed to albuterol in media for 72 hours, then mounted in Ussing chambers and CFTR function was assessed under voltage clamp conditions. (A) Representative short-circuit current (I_sc) tracings from wtCFTR⁺ CFBE41o- cells chronically exposed to increasing doses of albuterol (amiloride perfusion is not shown for clarity as these cells do not demonstrate significant epithelial sodium channel expression; see ref. 62); aggregate data are presented in C (n = 5 inserts/condition; circles represent total CFTR activity [cAMP + genistein], diamonds represent inhibited CFTR currents [Inh172]). (B) Representative I_sc tracings from control and albuterol-treated (10 μM) primary wtCFTR⁺ HAECs; aggregate data are presented in D (n = 3 inserts/condition). (E) wtCFTR⁺ CFBE41o- cells treated with 10 μM albuterol, studied with and without basolateral permeabilization (basolateral nystatin, 50 μg/ml). Permeabilization does not modify inhibition of stimulated I_sc with albuterol pretreatment (n = 3 inserts/condition). All data were normalized to the control (no albuterol pretreatment) condition. Stimulation protocol was as follows: amiloride (100 μM, not shown for CFBE41o- cells), cAMP (10 μM forskolin/100 μM IBMX; dark gray bars), CFTR potentiator (50 μM genistein; light gray bars), and CFTR inhibition (10 μM Inh172; white bars). All experiments are representative of studies repeated in duplicate or triplicate with similar results. Data presented represent the mean ± SEM. *P < 0.05; ***P < 0.005; ****P < 0.0005; NS, nonsignificant by 2-way ANOVA with Tukey’s multiple comparisons test.