Angiotensin II activates H+‐ATPase in type A intercalated cells in mouse cortical collecting duct

ANG II increases Cl − absorption in the mouse CCD by increasing transcellular transport across type B intercalated cells, through an H + ‐ATPase and Cl − /HCO 3 − exchanger (pendrin)‐dependent mechanism. Thus, we asked if ANG II induces subcellular redistribution of pendrin or the H + ‐ATPase, using quantitative immunogold cytochemistry of mouse CCDs perfused in vitro. ANG II (10 nM) application to the bath did not change the subcellular distribution of pendrin or the H + ‐ATPase in B cells, but increased apical plasma membrane H + ‐ATPase expression 3‐fold in A intercalated cells. To determine if ANG II increases H + ‐ATPase‐mediated H + secretion, J t‐CO2 was measured under identical conditions. Under basal conditions, HCO 3 − secretion was observed (J t‐CO2 = −4.2 ± 2.2 pmol/mm/min), while HCO 3 − absorption (J t‐CO2 = 2.5 ± 1.1 pmol/mm/min, P < 0.05) was observed with ANG II applied to the bath, consistent with apical H + ‐ATPase activation. Finally, application of the H + ‐ATPase inhibitor, bafilomycin, generated a more lumen‐negative transepithelial voltage, V T , in the presence, but not in the absence of ANG II. Conclusions: ANG II increases apical plasma membrane H + ‐ATPase expression and function. Increased H + secretion may increase NaCl absorption by: stimulating apical Cl − /HCO 3 − exchange by reducing luminal HCO 3 − concentration and increasing CO 2 formation and shunting V T generated by ENaC‐mediated Na + absorption.