[Relations between gastrointestinal interdigestive motility and secretion]

Abstract

The motility of the upper gastrointestinal tract in the interdigestive state shows a cycling pattern called Migrating Motor Complex (MMC) and is composed by phases I, II and III. Gastric, biliary and pancreatic secretion show cyclical fluctuations during fasting closely associated with the motor activity. The motor and secretory interdigestive activity is regulated by a complex interplay of nerval and humoral mechanisms. Among them, motilin, a gastrointestinal hormone mainly secreted from the duodenum, is supposed to play a central role in the initiation of phase III. Gastric acid secretion, directly or by means of motilin release, may modulate the duration of the MMC and the propagation of phase III in the small intestine. Pancreatic secretion does not initiate phase III but may exert a control on gastric interdigestive motility probably by means of pancreatic polypeptide release. Biliary interdigestive secretion seems to play a little or no role in the control of these phenomena. The coordination of motor and secretory events is likely to be under control of the duodenum.