Bioassay of cholecystokinin in the duodenal mucosa.

Cholecystokinin (CCK)-like activities in the duodenal mucosa were measured by bioassay in patients with duodenal ulcer, cholelithiasis and some other gastrointestinal diseases as well as in healthy normal subjects. The mean CCK-like activity of the duodenal mucosa in patients with duodenal ulcer and cholelithiasis was 0.405 Ivy dog units per milligram and 0.376 Ivy dog units per milligram of dry weight of the duodenal mucosa (IDU/mg d.w.), respectively. Both these figures are significantly higher than 0.180 IDU/mg d.w. in normal subjects (p less than 0.005, p less than 0.005, respectively). It can be speculated that the CCK-level of the duodenal mucosa in patients with cholelithiasis may be regulated by a feedback mechanism and CCK in patients with duodenal ulcer may act physiologically for the cure of duodenal ulcer.