Cholecystokinin Release by Gastric Distension – An Atropine-Sensitive Mechanism

The effect of gastric distension on plasma cholecystokinin (CCK), pancreatic polypeptide (PP) and gastrin concentrations was investigated in healthy volunteers. Fundic and antral distension was achieved by balloons attached to a gastric tube and inflated with 300 and 600 ml and 100 and 200 ml of air for fundic and antral distension, respectively. Gastric juice was continuously aspirated. Fundic distension was additionally studied during a concomitant intravenous infusion of atropine (5 µg/kg/h) or a bolus injection of propranolol (2 mg). Fundic distension with 300 ml caused a significant increase in PP release (+ 17% above basal). Distension with 600 ml significantly stimulated CCK (+ 81 %), gastrin (+ 31 %) and PP output (+ 74%) over 30 min. Atropine completely blocked PP release and almost abolished CCK release, whereas gastrin output was enhanced. Propranolol did not prevent CCK release induced by fundic distension, whereas gastrin and PP responses were diminished. Antral distension did not cause any significant changes in hormone response. In conclusion, we demonstrated a gastric phase of CCK release which is atropine sensitive, but not influenced by propranolol.