[Prostaglandins and the resistance of the gastroduodenal mucosa].

The mechanisms responsible for maintaining the integrity of the gastroduodenal mucosa have been explored intensively in recent years. Prostaglandins seem to play a central role in mucosal defence. Important mechanisms by which prostaglandins may produce cytoprotection include regulation of the thickness and the composition of the mucus layer at the epithelial surface; modulation of active bicarbonate secretion by the surface epithelial cells; hydrophobicity of the surface epithelium; rapid cell proliferation and differentiation after mucosal damage; maintenance of interstitial bicarbonate; and the integrity of the microcirculation--in addition to synthesis of mucosal sulphhydryl groups. A defect mucosal defence is considered the most important pathogenetic factor in the majority of patients with peptic ulcer disease, but it is still unclear whether this is due to a deficiency in endogenous prostaglandins. Important risk factors for developing peptic ulcer disease, such as nonsteroidal antiinflammatory drugs and smoking, depress the formation of endogenous prostaglandins. The question of whether the use of direct cytoprotection may be relevant in ulcer therapy has yet not been solved and the rationale for substitution with prostaglandin analogues is to date empirical.