Cholecystokinin-like activity in the duodenal lumen of anaesthetized neonatal calves

Cholecystokinin like activity was measured in duodenal perfusates obtained from a 30 cm closed loop of the proximal duodenum in anaesthetized neonatal calves. The concentration and the output of the CCK activity in the duodenal perfusates increased significantly during pectrical stimulation of the vagus nerve, whereas the blood plasma concentration of CCK (external jugular vein and portal vein) remained unchanged and lower than that found in the duodenum. On the other hand, intravenous infusion of CCK raised the blood plasma but not the duodenal CCK concentrations. In conclusion, CCK-like activity is present in the duodenal lumen. The luminal release mechanism is at least partly regulated by the vagus nerves.