G542X rats exhibited no CFTR-dependent hyperpolarization following perfusion with chloride-free Ringer’s solution plus forskolin, whereas responses in wild type littermates were typical of other non-CF species (G542X = −0.4 ± 1.5 mV,wild type = −13.4 ± 3.5 mV, P < 0.01, Figures 2A,C) and prior publications (Kaza et al., 2017). This evidence concerns the gene CFTR and cystic fibrosis.