Colocalization of H-ATPase and H,K-ATPase immunoreactivity in the rat kidney

Urinary acidification in the collecting duct (CD) is via V-type H-ATPase and P-type H,K-ATPase. The localization and polar distribution of H-ATPase in intercalated cells (IC) have been well studied. The localization of H,K-ATPase to IC has been reported, but its intracellular distribution has not been defined. To colocalize these pumps, a murine monoclonal antibody (E11) to the 31-kd subunit of the H-ATPase and a rabbit antiserum (HK alpha N2) to a synthetic peptide based on the N terminus of the hog gastric H,K-ATPase alpha-subunit were used. In immunocytochemical staining of rat kidney, H,K-ATPase was present only in the IC of the CD with the same polar distribution as H-ATPase. The preabsorption of HK alpha N2 with affinity-purified bovine H-ATPase did not affect the H,K-ATPase staining, whereas preabsorption with the immunizing synthetic peptide eliminated immunoreactivity. HK alpha N2 stained only parietal cells in the rat gastric mucosa, whereas preimmune serum and E11 showed no immunoreactivity. On immunoblots of rat gastric mucosal microsomes, HK alpha N2 labeled a single 94-kd band, and this staining disappeared after preabsorption with the immunizing synthetic peptide. HK alpha N2 labeled no bands on immunoblots of affinity-purified bovine H-ATPase. All immunochemistry was negative with preimmune serum.(ABSTRACT TRUNCATED AT 250 WORDS)