Functional heterogeneity of parietal cells along the pit-gland axis

The gastric epithelium forms numerous short pits continuous with long tubular glands divisible into isthmus, neck, and base regions. Parietal cells are produced in the isthmus and migrate down to the neck and base regions as they mature and age. Stimulation of parietal cells is manifested by translocation of H⁺-K⁺-adenosinetriphosphatase-rich tubulovesicles (TV) from the cytoplasm into the secretory-apical (SA) membrane. In this study we used rabbit isolated gastric glands to examine the physiological responses of parietal cells to graded levels of stimulation. Quantitative morphometry was used to evaluate parietal cell response along the longitudinal axis of the gland. Acid secretion as estimated by [¹⁴C]aminopyrine uptake was well correlated with parallel enzymatic and immunoblot assays for the redistribution of H⁺-K⁺-ATPase from TV to SA membranes. These responses also correlated well with morphological transformations of parietal cells within the isthmus and neck regions of the gastric gland; however, parietal cells in the base of the gland showed very little morphological change in response to any of the stimuli used. The poor responsiveness of basal parietal cells is in agreement with observations of intact mucosa and suggests that older parietal cells may serve some function other than acid secretion.