39 Inhibition of CFTR slows forskolin-stimulated mucociliary clearance in ferret trachea

Abstract

Objective Mucus clearance is a primary defense mechanism of the airways. Mucus secretion and clearance are abnormal in diverse organs in humans with CF and in all CF animal models. To better understand the contribution of CFTR to mucociliary clearance (MCC), we asked if CFTR plays a role in ferret tracheal MCC by directly inhibiting CFTR with a selective CFTR inhibitor, CFTRinh172. Methods We measured MCC velocities in ex vivo adult ferret tracheas by following particle movements with time-lapse digital imaging (Jeong et al . 2014 AJP-lung, L83) in the presence or absence of CFTRinh172. Tracheas were mounted side-by side in a chamber that was sealed, 37°C-maintained, and continuously supplied with warmed, humidified 95% O 2 -5% CO 2 gas. Particle movements (MCC) were measured at 20 sec intervals for 30 min: 10 mM forskolin or 0.3 mM carbachol +/– CFTRinh172. Tissue viability was assessed by then stimulating MCC for 30 min with 0.3 mM carbachol plus 10 mM forskolin in the absence of CFTRinh172. Results CFTRinh172 significantly reduced forskolin-induced MCC but did not significantly decrease MCC-stimulated by 0.3 mM carbachol. The MCC increase to carbachol + forskolin given after either agonist alone was not inhibited by prior CFTRinh172 treatment. Conclusion The present study demonstrated an important contribution of CFTR activity to forskolin-stimulated increases in MCC. In the ex vivo ferret trachea, ∼66% inhibition was produced with CFTRinh172 pretreatment. Cholinergically stimulated MCC was reduced only ∼18% by CFTRinh172 (n.s.). MCC was synergistically increased by forskolin + carbachol. Supported by CFF and CFFT.