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Aspirin, acetyl salicylic acid, damages gastric mucosal cells. This effect is considered related to its inhibition of prostaglandin synthesis. On the other hand, sodium salicylate has been reported to be cytoprotective against drug damage to gastric mucosa in vivo. One reason for this difference is that salicylic acid, unlike acetyl salicylic acid does not inhibit prostaglandin synthesis by gastric mucosa in vivo. Previous studies on tissue culture cells from our laboratory have required gastric mucosa from fetal rats; this was time consuming and expensive. The purpose of this study was to develop a primary cell culture of adult rat fundic epithelial cells and to test the effect of sodium salicylate on: (1) prostaglandin (PGE2) production, (2) cell viability, (3) reducing cell damage by sodium taurocholate. Gastric epithelial cells were isolated from adult rat stomachs and cultured on collagen gel. Cells reached confluency on day 4 at which stage fibroblasts were rarely seen (less than 1%). Autoradiographic study showed that cultured cells incorporated [3-H] thymidine into nuclei. In histochemical studies, 94% of the cells contained PAS positive granules (mucous cells). Mucous granules were observed in the cytoplasm of the majority of cells by electronmicroscopy. These cells synthesised prostaglandin E2 as determined by radioimmunoassay. Indomethacin 10(-4) M strongly suppressed PGE2 production after 30 minutes while 10(-3) and 10(-4)M sodium salicylate had no effect. Pharmacologic concentrations of 10 mM sodium salicylate had no effect on PGE2 production at 30 minutes and only weakly inhibited production after one hour incubation. Sodium salicylate up to 30 mM had no effect on cell viability, a concentration of 50 mM being necessary to produce significant cell damage. Sodium salicylate 10 mM significantly protected cells against damage induced by 10 mM sodium taurocholate. We conclude: (i) adult rat gastric mucous epithelial cells can be successfully cultured in vitro; (ii) prostaglandin synthesis is inhibited by indomethacin but not by low doses of sodium salicylate; (iii) sodium salicylate does not damage gastric mucosal cells except at very high concentrations; (iv) sodium salicylate protects against damage to cells induced by sodium taurocholate.

Two aspirin tablets in 100 ml fluid will produce microscopical damage to the human stomach. A study was performed to determine whether a small amount of sodium bicarbonate (equivalent to one-third of a teaspoonful of baking soda) could protect against this damage. Sequential gastric biopsy specimens were taken from 15 healthy subjects before, during, and after intragastric instillation of one of the following isotonic solutions: saline; sodium bicarbonate; 600 mg aspirin suspended in sodium bicarbonate; and aspirin suspended in saline. On a separate day the same solutions were instilled, but gastric transmucosal potential differences were monitored. Light microscopy and scanning electron microscopy of the biopsy specimens showed occasional mucous degranulation of mucosal surface cells, but no cell damage during instillation of sodium bicarbonate. Light microscopy studies 10 minutes after aspirin in saline showed damage in 20% of surface cells, with focal areas of cellular disruption and microscopic erosions, but only 3.4% of cells were damaged after aspirin in bicarbonate and there were no erosions. Electron microscopy showed a damaged honeycombed appearance of surface epithelium after aspirin in saline and a normal cobblestone appearance after aspirin in bicarbonate. Aspirin dissolved in bicarbonate failed to induce the usual fall in potential difference.These findings indicate that sodium bicarbonate in amounts equivalent to one-third of a teaspoonful of baking soda protects the gastric mucosa against aspirin-induced damage and prevents the usual fall in potential difference after aspirin.

Endocrine cells of gastric and gut mucosa are commonly thought to be present only within mucosal glands. In a previous report, we described argyrophilic cells in the lamina propria in 40% of surgical gastric specimens, using light microscopy. All these patients had chronic gastritis. Argyrophilia, however, is a non-specific reaction which could occur in other than endocrine cells. The present study was undertaken to describe the ultrastructure of argyrophil cells in the lamina propria. In five patients with chronic gastritis, endoscopic biopsies were taken from the fundic, intermediate, and pyloric areas of the stomach. Single and/or clustered argyophil cells were seen by light microscopy in the lamina propria of the intermediate and pyloric areas. On electron-microscopy, these cells had the following characteristics of endocrine-like cells: they were characterised by numerous electron dense granules in the cytoplasm, 100-300 nm in diameter; the cytoplasm contained poorly-developed rough endoplasmic reticulum and well-developed smooth endoplasmic reticulum with occasional vesicles. Immunostaining gave negative results for various gastrointestinal hormones. These ultrastructural characteristics of lamina propria cells are similar to endocrine cells of the APUD series. We conclude that endocrine-like cells occur in the lamina propria of the human stomach in the presence of chronic gastritis.

Glucagon inhibits gastric acid secretion and increases the negativity of gastric mucosal potential difference (PD) in man. To test the hypothesis that the increased negativity of PD after glucagon in man could be due to decreased parietal cell canalicular membrane area, a quantitative ultrastructural analysis was carried out. Four healthy volunteers with normal gastric mucosa were submitted to biopsy before and 20 minutes after intravenous injection of 2 mg glucagon (G). This time corresponded with the maximal change in PD and a decrease in gastric acid secretion. Canalicular and tubulovesicular membrane area of 80 parietal cells (40 cells before glucagon and 40 cells after glucagon) were quantified by the Loud morphometric method. After glucagon, the oxyntic cell canalicular membrane area was reduced by one-fourth (P less than 0.05), while tubulovesicular membrane area showed an increase (P less than 0.05) at the same time. The decrease in the area of parietal cell canalicular membrane caused by glucagon may in part be responsible for increased negativity of the gastric PD caused by this hormone.