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. Parieta l cells are produced in the isthmus and migrate down to the neck and b ase regions as they mature and age. Stimulation of parietal cells is m anifested by translocation of H+-K+-adenosinetriphosphatase-rich tubul ovesicles (TV) from the cytoplasm into the secretory-apical (SA) membr ane. In this study we used rabbit isolated gastric glands to examine t he physiological responses of parietal cells to graded levels of stimu lation. Quantitative morphometry was used to evaluate parietal cell re sponse along the longitudinal axis of the gland. Acid secretion as est imated by [C-14]aminopyrine uptake was well correlated with parallel e nzymatic and immunoblot assays for the redistribution of H+-K+-ATPase from TV to SA membranes. These responses also correlated well with mor phological transformations of parietal cells within the isthmus and ne ck regions of the gastric gland; however, parietal cells in the base o f 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 o lder parietal cells may serve some function other than acid secretion.