Involvement of CFTR in ATP and HCO3‐ secretion in epididymal principal cells

Abstract

Luminal ATP and HCO3− induce apical membrane accumulation of V-ATPase in epididymal clear cells. We hypothesized that CFTR might participate in the regulation of luminal acidification by clear cells, via crosstalk with principal cells through ATP and HCO3− secretion. Using the epididymal principal cell lines, DC2 and PC1, and a luciferase assay, we showed that forskolin (Fsk) and adrenaline increased ATP release from DC2 but not PC1 cells. The CFTR inhibitor, CFTRinh172, reduced basal ATP release in both cell lines and blocked the Fsk-induced ATP-release in DC2 cells. The rate of intracellular pH recovery (dpHi/dt) after alkalinization caused by removal of CO2 and HCO3− was measured with BCECF as an assessment of HCO3− secretion. Fsk significantly increased dpHi/dt in DC2 but not PC1 cells. CFTRinh172 abolished Fsk-induced HCO3− secretion in DC2 cells. These results suggest that CFTR mediates basal levels of ATP and HCO3− secretion in both cell lines, and Fsk-activation in DC2 cells. Data are compatible with the hypothesis that ATP and HCO3−, secreted by principal cells, increase V-ATPase-dependent proton secretion by clear cells, allowing restoration of luminal pH to its resting acidic value. This study provides new insights into the pathogenesis of cystic fibrosis-related male infertility.