Cytochemical localization of Ca++-ATPase, H+,K+-ATPase and Na+,K+-ATPase in acid-secreting parietal cell and non-secreting parietal cell.

Abstract

Ca++-activated adenosine triphosphatase (Ca++-ATPase), ouabain-insensitive, K+-dependent p-nitrophenylphosphatase (K+-NPPase), a component of H+, K+-ATPase system, and ouabain-sensitive K+-NPPase, a component of Na+, K+-ATPase system, were studied in the gastric parietal cells of guinea pigs fed ad libitum and/or starved using the recently improved cytochemical methods introduced by Ando et al. (1981), Fujimoto et al. (1986) and Mayahara et al. (1980), respectively.Ca++-ATPase activity was localized: a) on the exterior side of basal and lateral membranes, b) on the interior side of the membrane covering some tubulovesicles, c) just on the membrane covering Golgi apparatus and d) on the matrix of mitochondria. Ca++-ATPase activity on the mitochondria indicated the varying degrees of the intensity in the Ca++ concentration of the reaction medium and in a secretory state of parietal cell. Ca++-ATPase-positive tubulovesicles were not observed in the typical, acid-secreting, parietal cell. H+, K+-ATPase (ouabain-insensitive K+-NPPase) activity was recognized on the cytoplasmic side of: a) the apical plasma membrane, b) the secretory canalicular membrane, c) the tubulovesicular membrane and d) the lateral apical membrane showing the cell junction in both the acid-secreting and nonsecreting parietal cells. H+, K+-ATPase-negative tubulovesicles were also observed. On the other hand, Na+, K+-ATPase (ouabain-sensitive K+-NPPase) activity was observed on the cytoplasmic side of the basal and lateral membranes in both the acid-secreting and non-secreting parietal cells. Na+, K+-ATPase activity was also recognized on a few tubulovesicles of the non-secreting parietal cell.These findings indicate that: a) the cytochemical properties of the membranes are different between the apical surface, secretory canaliculus, the tubulovesicles and basal-lateral plasma membrane corresponding to the function and b) the tubulovesicles are not uniform in nature.