Helicobacter pylori, acid and gastrin.

Before the discovery of Helicobacter pylori, duodenal ulcers were thought to be caused by excessive acid secretion. Duodenal ulcer patients have more parietal cells than controls. In addition, they cannot suppress their acid secretion when the gastric lumen is empty or acidic. These changes, plus an increase in the release of gastrin were attributed to a paucity of the inhibitory peptide somatostatin in the gastric mucosa. It has now been established that the paucity of somatostatin and the failure to suppress acid secretion are actually the result of H. pylori infection. In patients without duodenal ulcers H. pylori infection is often associated with decreased acid secretion. This occurs on first infection and also later because H. pylori gastritis predisposes to gastric atrophy.