Gallbladder motility in sheep: effects of cholecystokinin and related peptides

Gallbladder motility was recorded as tonic and small amplitude (rhythmic) contractions in conscious sheep fitted with miniaturized strain-gauge force transducers located in the corpus and fundus. Nichrome wire electrodes were chronically implanted in the gastroduodenal area. Both tonic and superimposed rhythmic gallbladder contractions were increased during feeding. They decreased during the periodic phases of antroduodenal quiescence. The excitatory effects on gallbladder and antroduodenal motility were mimicked by pilocarpine and blocked by atropine. Cholecystokinin (CCK-OP) and caerulein elicited motor responses of the gallbladder in a dose-related manner without antroduodenal stimulation. In contrast, pentagastrin induced gallbladder motor responses with concomitant stimulation of the antroduodenal area. The results suggest that feeding may act to trigger gallbladder motor activity through a mechanism related to the increased antroduodenal activity. Direct effects of CCK-OP and caerulein confirm that gallbladder motor function is also mediated through specific receptor sites.