SLC26A4 and cystic fibrosis: Based on the critical role of SCTR in activating pendrin-mediated HCO3- secretion in kidney B-intercalated (B-IC) cells in response to oral base (e.g., HCO3-) loading, recent studies suggest that loss of SCTR in CF impairs the appropriate increase of renal base excretion during acute base loading and that SCTR is necessary for rapid correction of metabolic alkalosis (5, 36).