Enhanced calcium signaling and acid secretion in parietal cells isolated from gastrin-deficient mice

Abstract

Gastrin-deficient mice have impaired basal and agonist-stimulated gastric acid secretion. To analyze whether an intrinsic parietal cell defect contributed to the reduced acid secretion, we analyzed parietal cell calcium responses and acid secretory function in vitro. Parietal cells were purified by light-scatter cell sorting and calcium responses to gastrin, histamine, and carbachol were measured in gastrin-deficient and wild-type mice cell preparations. Surprisingly, basal and histamine-induced calcium concentrations were higher in the mutant cell preparations. [14C]aminopyrine uptake analysis in acutely isolated gastric glands revealed that basal acid accumulation was enhanced in gastrin-deficient cell preparations as well as on treatment with carbachol or histamine. These results suggested that an intrinsic parietal cell defect was not responsible for the reduced acid secretion in gastrin-deficient mice. Flow cytometric analysis of dispersed, H+-K+-ATPase-immunostained gastric mucosal preparations revealed a marked increase in parietal cell number in gastrin-deficient mice, which may have accounted for the enhanced in vitro acid secretion detected in this study. Parietal cells were found to be significantly smaller in the mutant cell preparations, suggesting that gastrin stimulation modulates parietal cell morphology.

Parietal cell hyperstimulation and autoimmune gastritis in cholera toxin transgenic mice

“…Dispersed fundic mucosal cells were prepared from Ctox-7 and Ntg mice by pronase digestion as described (17), fixed and permeabilized with the CytoFix/CytoPerm kit (Pharmingen), and cytospun onto slides. Cells were immunostained with a Ctox antibody that had been preabsorbed on paraffin sections from Ntg stomach to reduce nonspecific binding.…”

“…In contrast, histamine binding to the histamine-2 (H 2 ) receptor couples primarily to G s , which activates adenylate cyclase and evokes an increase in cAMP (8,9), although it has been shown in some species, including the mouse, to also increase calcium (10,17). It is not clear what independent roles these signaling pathways have for acid secretion in vivo.…”

Hip1r is expressed in gastric parietal cells and is required for tubulovesicle formation and cell survival in mice

“…Parietal cells from 2-monthold WT and Hip1r-deficient mice were quantified using a BD FACSVantage SE cell sorter as described previously (54). Briefly, gastric corpus was isolated from individual mice, and epithelial cells were dispersed with pronase, fixed, and permeabilized using the Cytofix/Cytoperm Kit (BD Biosciences - Pharmingen).…”

Achlorhydria is associated with gastric microbial overgrowth and development of cancer: Lessons learned from the gastrin knockout mouse

“…Even though the parietal cells in the gastrin KO mice in vivo were inactive and unresponsive to challenge with histamine, gastrin and carbachol (a M3 receptor agonist) [24], isolated parietal cells from the gastrin KO mice are active in vitro [38]. Following stimulation by gastrin, histamine and carbachol, they display increased intracellular calcium concentrations and increased aminopyrine accumulation [38].…”

“…Following stimulation by gastrin, histamine and carbachol, they display increased intracellular calcium concentrations and increased aminopyrine accumulation [38]. They are thus functional in vitro but dormant in vivo, which suggests that in vivo there was an overweight of inhibitory signals in the absence of gastrin.…”