Hormonal (gastrin, secretin, cholecystokinin) and secretory effects of bombesin and duodenal acidification in dogs.

We have studied the influences of duodenal acidification on the effects of bombesin on gastric and pancreatic secretion and on blood levels of gastrin, secretin, and cholecystokinin (CCK) in six conscious dogs with chronic gastric and pancreatic fistulas. Duodenal acidification suppressed bombesin-stimulated gastric acid output (from 20.1 +/- 4.2 to 8.2 +/- 1.9 mEq/120 min) and gastrin release (from an integrated 2-hour output of 16.0 +/- 1.2 to 11.1 +/- 1.1 ng-min/ml). On the other hand, duodenal acidification augmented bombesin-stimulated secretion of pancreatic bicarbonate (from 0.75 +/- 0.12 to 7.81 +/- 2.0 mEq/120 min) and protein (from 0.57 +/- 0.10 to 1.00 +/- 0.18 gm/120 min). Blood levels of CCK (but not of secretin) were increased with bombesin alone, whereas blood levels of secretin (but not CCK) were increased by duodenal acidification alone. Bombesin plus duodenal acidification resulted in increase of both CCK and secretin. This increase of secretin may be responsible, in part, for suppression of both gastric acid output and gastrin release, as well as for increases in pancreatic secretion of bicarbonate and protein.