Cholecystokinin Octapeptide and Cerulein Inhibit Ovine Duodenal Motility in a Dose- and Region-specific Manner

The aim of this study was to examine the influence of cholecystokinin (CCK)-octapeptide (OP) and its amphibian analogue cerulein infusions on duodenal myoelectric and motor activities, as well as to compare the effects of CCK peptides on duodenal bulb and duodenal motility in non-fasted conscious rams. Five rams underwent implantation of bipolar platinum electrodes to the duodenal bulb, and distal duodenum, as well as a strain gauge force transducer near the duodenal electrode. During continuous myoelectrical and motor recordings, 0.15 M NaCl or CCK peptides were administered intravenously. Infusions of CCK-OP at doses of 5 and 50 ng/kg/min and infusions of cerulein at doses of 0.5 and 1.5 ng/kg/min were applied for 60 min and started 15 min after the onset of the duodenal phase 2b of the migrating motor complex. The higher infusion dose of the CCK-OP in the duodenal bulb triggered the strong inhibitory response within few minutes following the start of infusion while in the duodenum its inhibitory effect was shorter and arrived within 40-50 min following the onset of the infusion. The higher dose of cerulein evoked a reaction similar to CCK-OP response in the duodenal bulb while in the duodenum the clear inhibitory response arrived about 20 min earlier than after CCK-OP. A lower infusion dose of CCK peptides evoked less pronounced effects. It is concluded that CCK-OP inhibits ovine duodenal motility in a dose-and region-specific manner. This effect seems to be physiological.