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Background/aims: Prostaglandin E2 (PGE2) plays an important role in the inhibition of gastric acid production and exerts cytoprotective action. The in vitro and in vivo effect of magaldrate, an aluminum containing antacid, on PGE2 synthesis in the gastric mucosa was investigated., Methodology: In the first part of the study, magaldrate was added to a suspension of isolated gastric mucosal cells. In the second part, the antacid gel was applied to the gastric mucosa during gastroscopy and biopsies were taken from the same site 5 and 10 min later., Results: The antacid significantly stimulated PGE2 release from the suspension of isolated gastric cells in vitro. The biopsies obtained after the application of magaldrate showed an increased PGE2 production compared to specimens obtained before., Conclusions: The data suggest that in addition to its neutralizing capacity as an antacid, magaldrate contributes to the cytoprotective activity of the mucosa by stimulating endogenous PGE2 synthesis.

Background/aims: The effect of calcium on colonic prostaglandin E2 synthesis was investigated in 26 healthy volunteers., Material and Methods: Biopsy specimens were obtained by colonoscopy and the mucosal cells were separated biochemically. The cells were incubated in EDTA or CaCl2 containing media for 15 and 30 minutes., Results: The PGE2 synthesis was significantly (p < 0.001) diminished in the calcium free suspension (EDTA) compared to the CaCl2 containing suspension. To increase intracellular Ca2+ concentration, calcium ionophore A 23187 was added for the last 15 minutes. It significantly stimulated the prostaglandin production. In addition, the calcium channel blocker verapamil did not alter the PGE2 synthesis, whereas trifluoperazine, a calmodulin inhibitor, markedly decreased the production rate., Conclusion: Calcium is an important stimulus of prostaglandin synthesis and inhibition of calmodulin by trifluoperazine decreases the arachidonic metabolism. In these regards, colonic tissue shares features with other tissues. However, in contrast to smooth or cardiac muscle, intracellular calcium concentration in colonic mucosa is not affected by verapamil, indicating that colonic calcium channels have a different affinity to this drug.

Background: Eicosanoid mediators play an important role in the pathogenesis of chronic inflammatory bowel disease., Materials and Methods: The synthesis of prostaglandin E2 and leukotriene B4 in biopsied colonic specimens from patients with inflammatory bowel disease was compared with that from healthy controls. In contrast to surgical resection, biopsy by colonoscopy enabled patients with milder disease to be investigated., Results: In subjects with Crohn's disease or ulcerative colitis, the synthesis of PGE2 was significantly (p < 0.05) increased, whereas synthesis of LTB4 remained unaltered. In addition, no differences in PGE2 and LTB4 production were found in different age groups or sex., Conclusion: We conclude that prostaglandin E2, compared to leukotriene B4, is the dominant eicosanoid in moderate inflammatory bowel disease.

Background/aims: Prostaglandin inhibits gastric acid secretion and exerts protective action on the mucosa of the stomach. We studied the synthesis of prostaglandin E2 (PGE2) to determine the role of PGE2 in peptic ulcer disease., Materials and Methods: Mucosal biopsies from 22 persons were obtained and incubated. PGE2 was then determined by radioimmunoassay., Results: Compared to healthy subjects, patients with gastric ulcers or gastritis show diminished accumulation of PGE2 in the incubation medium. Other factors like age, gender, and alcohol consumption were also investigated, however, they do not influence endogenous prostaglandin production. In contrast, PGE2 synthesis was found to be decreased in smokers., Conclusions: Our data indicates a deficiency in endogenous PGE2 synthesis as one cause of gastric ulcerations and offer an explanation of the higher incidence of gastric ulcer disease in subjects with nicotine abuse.