scholarly journals Deletion of the chloride transporter Slc26a9 causes loss of tubulovesicles in parietal cells and impairs acid secretion in the stomach

2008 ◽  
Vol 105 (46) ◽  
pp. 17955-17960 ◽  
Author(s):  
Jie Xu ◽  
Penghong Song ◽  
Marian L. Miller ◽  
Frank Borgese ◽  
Sharon Barone ◽  
...  
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Cultured Cells ◽  
Normal Growth ◽  
Chloride Secretion ◽  
Parietal Cells ◽  
Gastric Glands ◽  
Anion Transporter ◽  
Immunofluorescence Labeling

Slc26a9 is a recently identified anion transporter that is abundantly expressed in gastric epithelial cells. To study its role in stomach physiology, gene targeting was used to prepare mice lacking Slc26a9. Homozygous mutant (Slc26a9−/−) mice appeared healthy and displayed normal growth. Slc26a9 deletion resulted in the loss of gastric acid secretion and a moderate reduction in the number of parietal cells in mutant mice at 5 weeks of age. Immunofluorescence labeling detected the H-K-ATPase exclusively on the apical pole of gastric parietal cells in Slc26a9−/− mice, in contrast to the predominant cytoplasmic localization in Slc26a9+/+ mice. Light microscopy indicated that gastric glands were dilated, and electron micrographs displayed a distinct and striking absence of tubulovesicles in parietal cells and reductions in the numbers of parietal and zymogen cells in Slc26a9−/− stomach. Expression studies indicated that Slc26a9 can function as a chloride conductive pathway in oocytes as well as a Cl−/HCO3− exchanger in cultured cells, and localization studies in parietal cells detected its presence in tubulovesicles. We propose that Slc26a9 plays an essential role in gastric acid secretion via effects on the viability of tubulovesicles/secretory canaliculi and by regulating chloride secretion in parietal cells.

scholarly journals The calcium-sensing receptor acts as a modulator of gastric acid secretion in freshly isolated human gastric glands

2005 ◽  
Vol 289 (6) ◽  
pp. G1084-G1090 ◽  
Author(s):  
Matthias M. Dufner ◽  
Philipp Kirchhoff ◽  
Christine Remy ◽  
Patricia Hafner ◽  
Markus K. Müller ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Divalent Cations ◽  
Parietal Cells ◽  
Trivalent Cation ◽  
Calcium Sensing Receptor ◽  
Gastric Glands ◽  
Calcium Sensing

Gastric acid secretion is activated by two distinct pathways: a neuronal pathway via the vagus nerve and release of acetylcholine and an endocrine pathway involving gastrin and histamine. Recently, we demonstrated that activation of H+-K+-ATPase activity in parietal cells in freshly isolated rat gastric glands is modulated by the calcium-sensing receptor (CaSR). Here, we investigated if the CaSR is functionally expressed in freshly isolated gastric glands from human patients undergoing surgery and if the CaSR is influencing histamine-induced activation of H+-K+-ATPase activity. In tissue samples obtained from patients, immunohistochemistry demonstrated the expression in parietal cells of both subunits of gastric H+-K+-ATPase and the CaSR. Functional experiments using the pH-sensitive dye 2′,7′-bis-(2-carboxyethyl)-5-(and 6)-carboxyfluorescein and measurement of intracellular pH changes allowed us to estimate the activity of H+-K+-ATPase in single freshly isolated human gastric glands. Under control conditions, H+-K+-ATPase activity was stimulated by histamine (100 μM) and inhibited by omeprazole (100 μM). Reduction of the extracellular divalent cation concentration (0 Mg2+, 100 μM Ca2+) inactivated the CaSR and reduced histamine-induced activation of H+-K+-ATPase activity. In contrast, activation of the CaSR with the trivalent cation Gd3+ caused activation of omeprazole-sensitive H+-K+-ATPase activity even in the absence of histamine and under conditions of low extracellular divalent cations. This stimulation was not due to release of histamine from neighbouring enterochromaffin-like cells as the stimulation persisted in the presence of the H2 receptor antagonist cimetidine (100 μM). Furthermore, intracellular calcium measurements with fura-2 and fluo-4 showed that activation of the CaSR by Gd3+ led to a sustained increase in intracellular Ca2+ even under conditions of low extracellular divalent cations. These experiments demonstrate the presence of a functional CaSR in the human stomach and show that this receptor may modulate the activity of acid-secreting H+-K+-ATPase in parietal cells. Furthermore, our results show the viability of freshly isolated human gastric glands and may allow the use of this preparation for experiments investigating the physiological regulation and properties of human gastric glands in vitro.

Impaired gastric acid secretion in gastrin-deficient mice

1998 ◽  
Vol 274 (3) ◽  
pp. G561-G568 ◽  
Author(s):  
Lennart Friis-Hansen ◽  
Frank Sundler ◽  
Ying Li ◽  
Patrick J. Gillespie ◽  
Thomas L. Saunders ◽  
...  
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Histidine Decarboxylase ◽  
Embryonic Stem ◽  
Parietal Cells ◽  
Gastric Glands ◽  
Partial Restoration ◽  
Ecl Cells ◽  
Deficient Mice

To further understand the role of the peptide hormone gastrin in the development and function of the stomach, we have generated gastrin-deficient mice by gene targeting in embryonic stem cells. Mutant mice were viable and fertile, without obvious visible abnormalities. However, gastric function was severely affected by the loss of gastrin. Basal gastric acid secretion was abolished and could not be induced by histamine, carbachol, or gastrin. Histological analysis revealed alterations in the two cell types primarily involved in acid secretion, parietal and enterochromaffin-like (ECL) cells. Parietal cells were reduced in number with an accumulation of immature cells lacking H+-K+-adenosinetriphosphatase (H+-K+-ATPase). ECL cells were positioned closer to the base of the gastric glands, with markedly lower expression of histidine decarboxylase. Gastrin administration for 6 days reversed the effects of the gastrin deficiency, leading to an increase in the number of mature, H+-K+-ATPase-positive parietal cells and a partial restoration of acid secretion. The results show that gastrin is critically important for the function of the acid secretory system.

Identification of a basolateral Cl−/HCO 3 − exchanger specific to gastric parietal cells

2003 ◽  
Vol 284 (6) ◽  
pp. G1093-G1103 ◽  
Author(s):  
Snezana Petrovic ◽  
Xie Ju ◽  
Sharon Barone ◽  
Ursula Seidler ◽  
Seth L. Alper ◽  
...  
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Basolateral Membrane ◽  
Parietal Cells ◽  
Rt Pcr ◽  
Functional Studies ◽  
Distribution Studies ◽  
Immunofluorescence Labeling ◽  
Gastric Parietal Cells

The basolateral Cl−/HCO[Formula: see text] exchanger in parietal cells plays an essential role in gastric acid secretion mediated via the apical gastric H+-K+-ATPase. Here, we report the identification of a new Cl−/HCO[Formula: see text]exchanger, which shows exclusive expression in mouse stomach and kidney, with expression in the stomach limited to the basolateral membrane of gastric parietal cells. Tissue distribution studies by RT-PCR and Northern hybridizations demonstrated the exclusive expression of this transporter, also known as SLC26A7, to stomach and kidney, with the stomach expression significantly more abundant. No expression was detected in the intestine. Cellular distribution studies by RT-PCR and Northern hybridizations demonstrated predominant localization of SLC26A7 in gastric parietal cells. Immunofluorescence labeling localized this exchanger exclusively to the basolateral membrane of gastric parietal cells, and functional studies in oocytes indicated that SLC26A7 is a DIDS-sensitive Cl−/HCO[Formula: see text] exchanger that is active in both acidic and alkaline pHi. On the basis of its unique expression pattern and function, we propose that SLC26A7 is a basolateral Cl−/HCO[Formula: see text] exchanger in gastric parietal cells and plays a major role in gastric acid secretion.

scholarly journals CORRELATION OF THE FINE STRUCTURE OF THE GASTRIC PARIETAL CELL (DOG) WITH FUNCTIONAL ACTIVITY OF THE STOMACH

1961 ◽  
Vol 11 (2) ◽  
pp. 349-363 ◽  
Author(s):  
A. W. Sedar ◽  
M. H. F. Friedman
Keyword(s):  
Fine Structure ◽  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Parietal Cell ◽  
Parietal Cells ◽  
Gastric Glands ◽  
Secretory Cycle ◽  
Thin Sections ◽  
Acid Secreting

The fine structure of the parietal (oxyntic) cell in the gastric glands (corpus of the stomach) of the dog was examined under conditions of active gastric acid secretion and compared with cellular structure in the non-acid-secretory (basal) state. Animals, in both acute and chronic experiments, were equipped with gastric fistulae so that gastric juice could be collected for analysis of total acidity, free acidity, volume, and pH prior to biopsy of the gastric mucosa. The specimens of mucosa were fixed in buffered OsO4 and embedded in n-butyl methacrylate and the thin sections were stained with lead hydroxide before examination in the electron microscope. A majority of parietal cells showed an alteration of fine structure during stimulation of gastric acid secretion by a number of different techniques (electrical vagal stimulation, histamine administration, or insulin injection). The changes in fine structure affected mainly the smooth surfaced vesicular elements and the intracellular canaliculi in the cytoplasm of the cell. The mitochondria also appeared to be involved to some extent. During acid secretion a greater concentration of smooth surface profiles is found adjacent to the walls of the intracellular canaliculi; other parietal cells exhibited a marked decrease in number of smooth surfaced elements. Intracellular canaliculi, always present in non-acid-secreting oxyntic cells, develop more extensively in cells of acid-secreting gastric glands. The surface area of these canaliculi is greatly increased by the elaboration of a large number of closely approximated and elongated microvilli. Still other parietal cells apparently in a different stage of the secretory cycle exhibit non-patent canaliculi lacking prominence; such cells have very few smooth surfaced vesicular elements. These morphological findings correlated with the acid-secretory state of the stomach provide evidence that the parietal cell participates in the process of acid secretion.

Nitric oxide inhibits gastric acid secretion by increasing intraparietal cell levels of cGMP in isolated human gastric glands

2005 ◽  
Vol 289 (6) ◽  
pp. G1061-G1066 ◽  
Author(s):  
Anna Berg ◽  
Stefan Redéen ◽  
Magnus Grenegård ◽  
Ann-Charlott Ericson ◽  
Sven Erik Sjöstrand
Keyword(s):  
Nitric Oxide ◽  
Gastric Mucosa ◽  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Enzymatic Digestion ◽  
Human Gastric Mucosa ◽  
Gastric Glands ◽  
Oxyntic Mucosa ◽  
No Donor

We have previously identified cells containing the enzyme nitric oxide (NO) synthase (NOS) in the human gastric mucosa. Moreover, we have demonstrated that endogenous and exogenous NO has been shown to decrease histamine-stimulated acid secretion in isolated human gastric glands. The present investigation aimed to further determine whether this action of NO was mediated by the activation of guanylyl cyclase (GC) and subsequent production of cGMP. Isolated gastric glands were obtained after enzymatic digestion of biopsies taken from the oxyntic mucosa of healthy volunteers. Acid secretion was assessed by measuring [14C]aminopyrine accumulation, and the concentration of cGMP was determined by radioimmunoassay. In addition, immunohistochemistry was used to examine the localization of cGMP in mucosal preparations after stimulation with the NO donor S-nitroso- N-acetylpenicillamine (SNAP). SNAP (0.1 mM) was shown to decrease acid secretion stimulated by histamine (50 μM); this effect was accompanied by an increase in cGMP production, which was histologically localized to parietal cells. The membrane-permeable cGMP analog dibuturyl-cGMP (db-cGMP; 0.1–1 mM) dose dependently inhibited acid secretion. Additionally, the effect of SNAP was prevented by preincubating the glands with the GC inhibitor 4 H-8-bromo-1,2,4-oxadiazolo[3,4-d]benz[b][1,4]oxazin-1-one (10 μM). We therefore suggest that NO in the human gastric mucosa is of physiological importance in regulating acid secretion. Furthermore, the results show that NO-induced inhibition of gastric acid secretion is a cGMP-dependent mechanism in the parietal cell involving the activation of GC.

scholarly journals Gene expression profiling of gastrin target genes in parietal cells

2006 ◽  
Vol 24 (2) ◽  
pp. 124-132 ◽  
Author(s):  
Renu N. Jain ◽  
Cynthia S. Brunkan ◽  
Catherine S. Chew ◽  
Linda C. Samuelson
Keyword(s):  
Gene Expression ◽  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Parietal Cell ◽  
Target Genes ◽  
Adaptor Protein ◽  
Parietal Cells ◽  
Cell Gene Expression ◽  
Cell Gene

Previous studies demonstrated that mice with a null mutation in the gene encoding the hormone gastrin have impaired gastric acid secretion. Hence, the aim of this study was to evaluate changes in the acid-secreting parietal cell in gastrin-deficient (GAS-KO) mice. Analysis of several transcripts encoding parietal cell proteins involved in gastric acid secretion showed reduced abundance in the GAS-KO stomach, including H+,K+-ATPase α- and β-subunits, KCNQ1 potassium channel, aquaporin-4 water channel, and creatine kinase B, which were reversed by gastrin infusion for 1 wk. Although mRNA and protein levels of LIM and SH3 domain-containing protein-1 (LASP-1) were not greatly changed in the mutant, there was a marked reduction in phosphorylation, consistent with its proposed role as a cAMP signal adaptor protein associated with acid secretion. A more comprehensive analysis of parietal cell gene expression in GAS-KO mice was performed using the Affymetrix U74AV2 chip with RNA from parietal cells purified by flow cytometry to >90%. Comparison of gene expression in GAS-KO and wild-type mice identified 47 transcripts that differed by greater than or equal to twofold, suggesting that gastrin affects parietal cell gene expression in a specific manner. The differentially expressed genes included several genes in signaling pathways, with a substantial number (20%) known to be target genes for Wnt and Myc.

Neuronal nitric oxide synthase: expression in rat parietal cells

2001 ◽  
Vol 280 (2) ◽  
pp. G308-G313 ◽  
Author(s):  
Shyamal Premaratne ◽  
Chun Xue ◽  
John M. McCarty ◽  
Muhammad Zaki ◽  
Robert W. McCuen ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Intracellular Signaling ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Parietal Cells ◽  
Nadph Diaphorase ◽  
Rt Pcr ◽  
Oxyntic Mucosa

Nitric oxide synthases (NOS) are enzymes that catalyze the generation of nitric oxide (NO) from l-arginine and require nicotinamide adenine dinucleotide phosphate (NADPH) as a cofactor. At least three isoforms of NOS have been identified: neuronal NOS (nNOS or NOS I), inducible NOS (iNOS or NOS II), and endothelial NOS (eNOS or NOS II). Recent studies implicate NO in the regulation of gastric acid secretion. The aim of the present study was to localize the cellular distribution and characterize the isoform of NOS present in oxyntic mucosa. Oxyntic mucosal segments from rat stomach were stained by the NADPH-diaphorase reaction and with isoform-specific NOS antibodies. The expression of NOS in isolated, highly enriched (>98%) rat parietal cells was examined by immunohistochemistry, Western blot analysis, and RT-PCR. In oxyntic mucosa, histochemical staining revealed NADPH-diaphorase and nNOS immunoreactivity in cells in the midportion of the glands, which were identified as parietal cells in hematoxylin and eosin-stained step sections. In isolated parietal cells, decisive evidence for nNOS expression was obtained by specific immunohistochemistry, Western blotting, and RT-PCR. Cloning and sequence analysis of the PCR product confirmed it to be nNOS (100% identity). Expression of nNOS in parietal cells suggests that endogenous NO, acting as an intracellular signaling molecule, may participate in the regulation of gastric acid secretion.

scholarly journals Gastric acid secretion in aquaporin-4 knockout mice

2000 ◽  
Vol 279 (2) ◽  
pp. G448-G453 ◽  
Author(s):  
Kasper S. Wang ◽  
Alex R. Komar ◽  
Tonghui Ma ◽  
Ferda Filiz ◽  
Jeff McLeroy ◽  
...  
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Basolateral Membrane ◽  
Water Channel ◽  
Normal Growth ◽  
Fluid Secretion ◽  
Gastric Fluid ◽  
Aquaporin 4 ◽  
Aqp4 Protein

The aquaporin-4 (AQP4) water channel has been proposed to play a role in gastric acid secretion. Immunocytochemistry using anti-AQP4 antibodies showed strong AQP4 protein expression at the basolateral membrane of gastric parietal cells in wild-type (+/+) mice. AQP4 involvement in gastric acid secretion was studied using transgenic null (−/−) mice deficient in AQP4 protein. −/− Mice had grossly normal growth and appearance and showed no differences in gastric morphology by light microscopy. Gastric acid secretion was measured in anesthetized mice in which the stomach was luminally perfused (0.3 ml/min) with 0.9% NaCl containing [14C]polyethylene glycol ([14C]PEG) as a volume marker. Collected effluent was assayed for titratable acid content and [14C]PEG radioactivity. After 45-min baseline perfusion, acid secretion was stimulated by pentagastrin (200 μg · kg−1· h−1 iv) for 1 h or histamine (0.23 mg/kg iv) + intraluminal carbachol (20 mg/l). Baseline gastric acid secretion (means ± SE, n = 25) was 0.06 ± 0.03 and 0.03 ± 0.02 μeq/15 min in +/+ and −/− mice, respectively. Pentagastrin-stimulated acid secretion was 0.59 ± 0.14 and 0.70 ± 0.15 μeq/15 min in +/+ and −/− mice, respectively. Histamine plus carbachol-stimulated acid secretion was 7.0 ± 1.9 and 8.0 ± 1.8 μeq/15 min in +/+ and −/− mice, respectively. In addition, AQP4 deletion did not affect gastric fluid secretion, gastric pH, or fasting serum gastrin concentrations. These results provide direct evidence against a role of AQP4 in gastric acid secretion.

Potassium channel KCNJ15 is required for histamine-stimulated gastric acid secretion

2015 ◽  
Vol 309 (4) ◽  
pp. C264-C270 ◽  
Author(s):  
Jianye Yuan ◽  
Wensheng Liu ◽  
Serhan Karvar ◽  
Susan S. Baker ◽  
Wenjun He ◽  
...  
Keyword(s):  
Acid Secretion ◽  
Gastric Acid Secretion ◽  
Gastric Acid ◽  
Apical Membrane ◽  
Imaging System ◽  
Parietal Cells ◽  
Live Cells ◽  
Protein Levels ◽  
Endogenous Protein ◽  
Luminal Side

Gastric acid secretion is mediated by the K+-dependent proton pump (H+,K+-ATPase), which requires a continuous supply of K+ at the luminal side of the apical membrane. Several K+ channels are implicated in gastric acid secretion. However, the identity of the K+ channel(s) responsible for apical K+ supply is still elusive. Our previous studies have shown the translocation of KCNJ15 from cytoplasmic vesicles to the apical membrane on stimulation, indicating its involvement in gastric acid secretion. In this study, the stimulation associated trafficking of KCNJ15 was observed in a more native context with a live cell imaging system. KCNJ15 molecules in resting live cells were scattered in cytoplasm but exhibited apical localization after stimulation. Furthermore, knocking down KCNJ15 expression with a short hairpin RNA adenoviral construct abolished histamine-stimulated acid secretion in rabbit primary parietal cells. Moreover, KCNJ15, like H+,K+-ATPase, was detected in all of the parietal cells by immunofluorescence staining, whereas only about half of the parietal cells were positive for KCNQ1 under the same condition. Consistently, the endogenous protein levels of KCNJ15, analyzed by Western blotting, were higher than those of KCNQ1 in the gastric mucosa of human, mouse, and rabbit. These results provide evidence for a major role of KCNJ15 in apical K+ supply during stimulated acid secretion.

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