[Defence mechanisms of the gastroduodenal mucosa. The significance of epithelial and subepithelial factors for the development of acute and chronic ulceration].

Extra-epithelial, epithelial and sub-epithelial defence mechanisms protect the gastroduodenal mucosa against acid and pepsin. The epithelial mechanisms include epidermal growth factor, surface active phospholipids on the luminal membrane of the epithelial cells, sulfhydryl compounds and rapid epithelial restitution after damage. The sub-epithelial mechanisms include mucosal blood flow supplying the mucosa with bicarbonate needed for neutralization of the acid which penetrates the epithelium and the protective effect of the process of acid secretion. Prostaglandins, which partially protect the gastroduodenal mucosa against damaging agents, stimulate several of the abovementioned defensive factors but the precise mechanism of the action of prostaglandins is still unknown. The results of several experiments support the idea of the defensive factors being of importance in the development of acute and chronic gastroduodenal ulceration. At present, the therapeutic possibilities seem to be restricted and nothing indicates that stimulation of the defensive factors, only, is more effective in the treatment of peptic ulcer than inhibition of aggressive factors as acid and pepsin.