Finally, to determine its potential for quantitative assessment of therapeutic interventions, we used confocal reflection microscopy to determine effects of low temperature rescue (27 °C) and ion channel modulators including the ENaC blocker benzamil, the Slc12a2 (NKCC1) inhibitor bumetanide and the CFTR modulator dual combination VX-809/VX-770 (lumacaftor/ivacaftor) on ASL height on primary human airway epithelial cultures from CF patients and non-CF controls. Here, SLC12A2 is linked to cystic fibrosis.