Mechanisms of bicarbonate secretion by the duodenum

The duodenal mucosa secretes a bicarbonate containing solution which supports a neutral pH in the unstirred mucous layer adjacent to the epithelium and thereby protects that organ from peptic ulcer disease. This secretion is stimulated primarily by gastric acid entering the duodenal lumen. Bicarbonate production is an active secretory process requiring carbonic anhydrase enzyme and is regulated by neural and hormonal pathways. Present research, as reviewed herein, relates to understanding the regulation of this secretion, the cellular pathways responsible for the generation and export of bicarbonate to the duodenal lumen, and the defects that are present in patients with duodenal ulcers, including those associated with Helicobacter pylori and stress.