CFTR and cystic fibrosis: Concurrent ASL height and CBF decreases were noted in human 3D airway epithelial cultures following exposure to cigarette smoke Åstrand et al. (2014); Xu et al. (2015) and following the addition of large dextran molecules, low-melting point agarose or endogenous mucus Button et al. (2012). Treatment of human airway epithelial with an ENaC inhibitor prevented the cigarette smoke effect on ASL height and CBF Åstrand et al. (2014). In addition, treatment of cystic fibrosis airway cultures with a CFTR-modifying drug increased both ASL height and CBF Van Goor et al. (2009)