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

Abstract

Activities of the H+, K(+)-ATPase and the Na+, K+, ATPase have been localized in the morphologically heterogeneous oxyntic cell lineage of adult bovine abomasal mucosa, by means of K(+)-dependent paranitrophenylphosphatase (K(+)-pNPPase) histochemistry. At the light- and electron-microscopic level, only members of the mature oxyntic cell population within the oxyntic glandular base exhibit strong enzyme activity. Superficial oxyntic cells of the proximal isthmus and deep pit, arising from the upward migration of precursor cells and commonly supposed to have a high capacity of secreting acid, show weak or no enzyme activity. This is also true of the immature and pre-oxyntic cells of the generative zone. Global enzyme activity varies among the mature glandular oxyntic cell population. Ultracytochemically, strong H+, K(+)-ATPase (ouabain-insensitive K(+)-pNPPase) activity is associated with the apical plasmalemmal and expanded canalicular membrane in contrast to Na+, K(+)-ATPase (ouabain-sensitive K(+)-pNPPase) activity, which is localized on the basolateral plasmalemmal folds. In both cases, histochemical deposition is confined to the cytoplasmic aspect of the membranes. These results suggest a functional zonation and position-dependent heterogeneity of the oxyntic cell lineage related to the bidirectional mode of migration of pre-oxyntic cells during physiological cell renewal. Functional heterogeneity within the mature glandular oxyntic cell population is in accordance with the continuous mode of gastric acid secretion in cattle.