Detection and localization of H1-K1-ATPase isoforms in human kidney

F763–F768, 2001.—An H1-K1-ATPase contributes to hydro-gen secretion and potassium reabsorption by the rat and rabbit collecting ducts. Transport of these ions appears to be accomplished by one or both of two isoforms of the H1-K1-ATPase, HKa1 and HKa2, because both isoforms are found in the collecting ducts and transport of hydrogen and potassium is attenuated by exposure to inhibitors of these transport proteins. To evaluate whether an H1-K1-ATPase is present in the human kidney, immunohistochemical studies were performed using normal human renal tissue probed with antibodies directed against epitopes of three of the known isoforms of the H1-K1-ATPase, HKa1, HKa2, and HKa4, and the V-type H1-ATPase. Cortical and medullary tissue probed with antibodies against HKa1 showed cytoplasmic staining of intercalated cells that was less intense than that observed i