Cholecystokinin, a hormone released from endocrine cells of the upper small intestine in
response to amino acids and fatty acids in chyme, has potent effects on gut smooth muscle
contractility. Depending on the region of the gut, the effect of cholecystokinin may be
neurally mediated, direct, or both. Neurally-mediated effects may be relaxant or contractile
depending on the transmitter released by cholecystokinin. Based on mimicry by infusion of
cholecystokinin to post-prandial levels and the ability of specific cholecystokinin receptor …