title: Annexin 7 in the regulation of gastric acid secretion.
abstract: OBJECTIVE
  Glucocorticoids enhance gastric acid secretion and inhibit gastric cyclooxygenase, thus downregulating formation of PGE2, an inhibitor of gastric acid secretion. In erythrocytes, PGE2 formation is inhibited by annexin 7. The present study thus explored whether annexin 7 participates in the regulation of gastric acid secretion.
  
  
  METHODS
  Annexin 7 protein expression was determined by Western blotting, cytosolic pH (pHi) of parietal cells utilizing BCECF-fluorescence, and gastric acid secretion by determination of Na(+)-independent pHi recovery from an ammonium pulse (∆pHi/min). Experiments were performed in isolated glands from gene targeted mice lacking annexin 7 (anx7(-/-)) and in respective wild type animals (anx7(+/+)).
  
  
  RESULTS
  Prior to treatment pHi and ∆pHi/min were similar in isolated gastric glands from anx7(-/-) and from anx7(+/+) mice. Aspirin (100 µM added to the glands 1 hr prior to the experiment) significantly increased ∆pHi/min to similar values in both genotypes. The administration of dexamethasone (10 µg/g BW subcutaneously for 4 consecutive days prior to the experiments) significantly increased ∆pH/min in anx7(+/+) mice but not in anx7(-/-) mice. Following dexamethasone treatment, the luminal pH was significantly lower and the acid content significantly higher in anx7(+/+) mice than in anx7(-/-) mice. An increase of extracellular K(+) concentration to 35 mM (replacing Na(+)/NMDG(+)) significantly increased ∆pHi/min in both genotypes. In neither genotype dexamethasone increased ∆pH/min further in the presence of 35 mM K(+) or presence of aspirin.
  
  
  CONCLUSIONS
  Annexin 7 is required for the stimulation of gastric acid secretion by glucocorticoids.
authors: Department of Physiology, University of Tübingen, Tübingen, Germany.
authors: Venkanna
authors: V
authors: Pasham
authors: Anand
authors: A
authors: Rotte
authors: Sobuj
authors: S
authors: Mia
authors: Ioana
authors: I
authors: Alesutan
authors: Soumya
authors: S
authors: Chatterjee
authors: Zohreh
authors: Z
authors: Hosseinzadeh
authors: Madhuri
authors: M
authors: Bhandaru
authors: Angelika A
authors: AA
authors: Noegel
authors: Florian
authors: F
authors: Lang
mesh_terms: D000818:Animals; D017310:Annexin A7 / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D001241:Aspirin / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D005452:Fluoresceins / Q000737:chemistry; D005744:Gastric Acid / Q000378:metabolism*; D005745:Gastric Acidity Determination / Q000662:veterinary; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D005838:Genotype; D006863:Hydrogen-Ion Concentration; D051379:Mice; D018345:Mice, Knockout; D010295:Parietal Cells, Gastric / Q000187:drug effects / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000737:chemistry / Q000378:metabolism
chemical_list: D017310:Annexin A7; D000893:Anti-Inflammatory Agents; D005452:Fluoresceins; D003907:Dexamethasone; C043829:2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein; D011451:Prostaglandin-Endoperoxide Synthases; D001241:Aspirin; D011188:Potassium