[The motoricity cycle of the small intestine].

The electrical spike activity of the small intestine at the gastroduodenal junction occurs as migrating myoelectric complexes (MMCs), initiated regularly at intervals of 90-100 min. in the adult sheep and of 20-30 min. in the neonate. This ultradian rhythm, generated by the enteric nervous system, may become identical in the adult and in the neonate, by the use of methysergide which interacts with 5-HT myenteric neurones. The results suggest a postnatal development of a serotoninergic inhibitory system, involved in the control of the basic rest-activity cycle of the small intestine.