Expression of gastric and colonic H(+)-K(+)-ATPase in the rat kidney.

Enzymatic and microperfusion studies have indicated that an ATP-dependent H+/K+ exchange process is present in the collecting duct of the mammalian kidney. Immunochemical staining has also provided evidence for expression of a gastric-type H(+)-K+ adenosine triphosphatase (H(+)-K(+)-ATPase). Rat kidney mRNA was probed with use of the polymerase chain reaction (PCR) to determine the presence of an H(+)-K(+)-ATPase. cDNA made with mRNA isolated from the kidneys of rats maintained on a low-K diet was used as template in PCR reactions with primers encompassing the cDNA sequence of the alpha-subunit of the gastric H(+)-K(+)-ATPase and the 5' and 3' ends of the colonic H(+)-K(+)-ATPase. The resulting products, 300-700 bp in size, hybridized with probes directed against either the gastric or colonic sequences of the H(+)-K(+)-ATPase. Sequencing of the individual PCR products showed identity with the appropriate regions of the alpha-subunits of the gastric H(+)-K(+)-ATPase and colonic H(+)-K(+)-ATPase. These data indicate that the rat kidney expresses mRNAs encoding both gastric and colonic H(+)-K(+)-ATPases.