H+-K+-ATPase in rabbit cortical collecting duct B-type intercalated cell

The role of H+-K+-adenosinetriphosphatase (H+-K+-ATPase) in the cortical collecting duct (CCD) B-type intercalated cell (B cell) is unclear. This study examined whether H+-K+-ATPase contributes to B cell intracellular pH (pH(i)) regulation and, if so, whether it is present at the apical or basolateral membrane. B cell Na+-independent pH(i) recovery from an acid load was only partially inhibited by peritubular N-ethylmaleimide (NEM). Complete inhibition required combining peritubular NEM either with luminal Sch-28080 or with luminal K+ removal. In contrast, neither peritubular Sch-28080 nor peritubular K+ removal altered pH(i) regulation. Tomato lectin, which binds to the gastric H+-K+-ATPase beta-subunit, labeled the B cell apical membrane. We conclude that the rabbit CCD B cell possesses an apical H+-K+-ATPase that plays an important role in pH(i) recovery from an in vitro acid load.