Motilin is a potent agonist for gastrointestinal smooth muscle contraction and has been proposed to regulate the onset of phase III of the migrating motor complex (MMC) in dogs and humans. In the dog, but not in the human, Motilin also contracts the gallbladder and sphincter of Oddi and induces pancreatic secretion. Motilin activates L-type Ca2+ channel (IcaL) in canine jejunal circular smooth muscle cells through a G protein-coupled mechanism. At 1 μM, Motilin increases IcaL in canine jejunal circular smooth muscle cells by 43±20[1].
