Gastrointestinal hormones.

The chemistry, localisation, release and effects of gastrointestinal hormones and some related peptides are surveyed. Their main presumed physiologic actions are: gastric acid and pepsin secretion are stimulated by gastrin and to a less degree by secretin. Acid secretion is inhibited by bulbo-enterogastrone and GIP. Biliary water and electrolytes are augmented by gastrin, CCK-PZ, secretin and VIP and inhibited by Substance P. Pancreatic bicarbonate and enzyme secretions are stimulated by secretin and CCK-PZ, especially in combination. Lower oesophageal and antral motility and tonus are elevated following gastrin and motilin; the gallbladder and small intestine empty following CCK. Gastrin regulates gastrointestinal, and CCK pancreatic, tissue growth. Somatostatin inhibits all gut hormones. All peptides are vasoactive within the splanchnic area, each one in a specific manner.