Inhibition of canine interdigestive proximal gastric motility by cholecystokinin octapeptide.

Feeding abolishes cyclic interdigestive motility and decreases intraluminal pressure in autotransplanted pouches of canine proximal stomach. Our aim was to determine whether cholecystokinin might be the hormonal messenger involved. In four conscious dogs with autotransplanted proximal gastric pouches and chronic duodenal electrodes, intrapouch pressure and duodenal myoelectric activity were measured during fasting, while cholecystokinin octapeptide (CCK-OP) was infused intravenously for 4 h at doses 0, 15, 31, 62, 125, and 250 mg . kg-1 . h-1. Each dose was given five times to each animal. Cholecystokinin octapeptide inhibited the interdigestive cycles in both pouch and duodenum and decreased the pressure in the pouch. The threshold for these effects was 31 ng . kg-1 . h-1, and the ED50 was 62 ng . kg-1 . h-1. The dose of 125 ng . kg-1 . h-1 suppressed the cycles nearly completely and decreased mean +/- SE intrapouch pressure from 15.3 +/- 1.1 to 6.3 +/- 2.8 cmH2O . min (P less than 0.001). After the infusions were stopped, cyclic activity and intrapouch pressure returned promptly to control values. We concluded that CCK-OP at "physiological" doses abolished interdigestive cycles and decreased intraluminal pressure in autotransplanted pouches of canine proximal stomach.