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 ol-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 cr-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.