IN-SITU HYBRIDIZATION OF MESSENGER-RNA FOR THE GASTRIC H-ATPASE IN RAT OXYNTIC MUCOSA(, K+)

The H+, K+-ATPase member of the phosphorylating ion motive ATPases is composed of two subunits, a large alpha-subunit composed of about 1030 amino acids and a smaller beta-subunit consisting of about 290 amino acids. By biochemical and immunological methods both subunits have bee n found in high abundance in the gastric parietal cell. In the present study in situ hybridization was used for localizing and comparing con centrations of the mRNA for the two subunits in the gastric epithelium . For this purpose H-3-labelled probes were preferred. Hybridization w as detected only in the parietal cells. The older parietal cells in th e bottom of the mucosa gave a weaker hybridization signal than the you nger parietal cells closer to the surface. The margin of experimental ulcers, where the parietal cells are of low differentiation, showed ve ry weak, if any, hybridization. The differences observed in hybridizat ion densities may reflect differences in mRNA synthesis or stability. It is conceivable that older parietal cells, as well as parietal cells of low differentiation, produce relatively small amounts of H+, K+-AT Pase.