Redistribution of gastric K⁺‐NPPase in vertebrate oxyntic cells in relation to hydrochloric acid secretion: A cytochemical study

Abstract

Gastric K+-NPPase represents a partial reaction of the (K+-H+)ATPase system, which is considered to be the proton pump in mammalian parietal cells. In the present paper, K+-NPPase activity was cytochemically studied by the method of Mayahara et al. (1980) in gastric glands of birds, amphibia, and mammals, either in the resting state induced by cimetidine or after stimulation of HCl secretion by histamine. The gastric K+-NPPase cytochemical reaction was localized only in oxyntic cells of the gastric mucosa in the three species tested. The subcellular distribution of the K+-NPPase reaction product drastically changes with the secretory state of HCl. In resting cells, the K+-NPPase staining is associated with the membranes of the endocellular tubular system while in HCl-secreting cells, it is associated with the plasma membrane of the elaborate secretory surface characteristic of this functional state. The above results demonstrate that the same enzymatic activity, which is associated with the gastric proton pump, is present in both membranous systems of the oxyntic cell secretory pole. This fact supports the proposal that the tubular system represents a membrane reserve that inserts the proton pump into the luminal plasma membrane in vertebrate oxyntic cells under the action of HCl secretagogues.

Heterogeneity and migration-related zonation of K + -ATPase activities in the oxyntic cell lineage of adult cattle

“…Exclusively luminal (apical and canalicular) and tubulo-vesicular membranes may exhibit enzyme activity of equal intensity (Fujimoto et al 1986) or the latter compartment may show weaker reactivity than the former (Ogawa et al 1987;Kobayashi and Seguchi 1990). Additionally, enzyme activities are thought to be bound to the basolateral plasma membrane (Koenig 1984;Pouyet et al 1992). …”

“…This is also the case for the closely related Na + ,K + -ATPase (Skou and Esmann 1992), which catalyzes active exchange of cellular sodium for extracellular potassium, thereby contributing to cationic homeostasis and controlling cellular function. Studies localizing these K + -transporting ATPases in the mammalian oxyntic cell type have been performed with enzyme-histochemical and immunocytochemical techniques (Rubin and Aliasgharpour 1976;Saccomani et al 1979;Firth and Stranks 1981;Smolka et al 1983;Coulton and Firth 1983;Koenig 1984;Ogawa et al 1987;Fujimoto et al 1986;Kobayashi and Seguchi 1990;Pouyet et al 1992;Jöns et al 1994;Karam and Forte 1994). In contrast to immunocytochemistry, which identifies the sites of enzyme expression, enzyme-histochemical procedures offer the opportunity to reveal actual catalytic activities.…”

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

“…There have been some attempts to localize H+, K+-ATPase activity on gastric parietal cell ultracytochemically using ATP or NPP as a substrate (24,38). However, they did not go so far as to distinguish H+, K+-ATPase activity from Nat, K+-ATPase activity and therefore to grasp the localization of each ATPase activity exactly.…”

“…Although there is much biochemical evidence showing the properties of Ca++-ATPase, H+, K+-ATPase and Na+, K+-ATPase in the gastric parietal cell, cytochemical studies of these enzymes have been restricted and have not reached to grasp the localization sufficiently (11,24,38). In order to elucidate the physiology of the parietal cell, it is necessary to demonstrate the cytochemical localization of these ATPases which control the movement of important ions on both the acidsecreting parietal cell and the non-secreting parietal cell.…”

An Immuno- and Enzyme Cytochemical Study of the H+-K+ ATPase in Human Parietal Cells after Administration of Tetragastrin and Omeprazole.

“…All of these are K+-dependent, and gastric K+-stimulated p-nitrophenylphosphatase (K+-pNPPase) is correlative to H+-K+ ATPase activity (LJUNGSTROM et al, 1984;KOENIG, 1984;RAY and NANDI,1986). To determine the activity of H+-K+ ATPase, FUJIMOTO et al (1986) devised a cytochemical method for demonstration of H+-K+ ATPase in ouabain-insensitive, K+-pNPPase with a lead based method, derived from the method for measuring Na+-K+ ATPase activity (MAYAHARA et al, 1980).…”