ität, Me

apical Cl channels. One of these channels, the cystic number of studies indicate that phenotypes with increased activity of alternate Cl channels such as the hemiIntroduction Transepithelial chloride flux by polarized epithelia controls a variety of physiological processes, such as intestinal and pancreatic secretion and renal functions.1 For example,Cl secretion regulates thefluidbalanceof the intestinal lumen,2 and is a driving force for the hydration of airway epithelia.3 Given this key role in physiological functions, defects inCl transport can result in life-threatening diseases, such as diarrhea and cystic fibrosis (CF).4 Transepithelial Cl secretion is gated through multiple fibrosis transmembrane regulator (CFTR) can be trig-gered by elevating cAMP levels, and consequently PKA-dependent phosphorylation.5 The vast majority o