Background Patients with cystic fibrosis (CF) do not respond with increased urinary HCO 3−
excretion after stimulation with secretin and often present with metabolic alkalosis. Methods
By combining RT-PCR, immunohistochemistry, isolated tubule perfusion, in vitro cell studies,
and in vivo studies in different mouse models, we elucidated the mechanism of secretin-
induced urinary HCO 3− excretion. For CF patients and CF mice, we developed a HCO 3-
drinking test to assess the role of the cystic fibrosis transmembrane conductance regulator …