Prostaglandins and gastrointestinal function.

Much work has been done and much remains to be done in defining the role of the prostaglandins in the physiology and pathophysiology of the gastrointestinal tract. The following statements summarize the current knowledge of the prostaglandins in human gastrointestinal function: 1. Prostaglandins of the E type have been isolated from human gastrointestinal tissue. They are naturally occurring 20 carbon hydroxy fatty acids synthesized and degraded in the same intestinal tissue by a 15-prostaglandin dehydrogenase. 2. Prostaglandins E2 and PGF2alpha have opposing, dose-related effects on the lower esophageal sphincter and lower two thirds of the esophagus. Sphincter pressure is decreased and esophageal contractions are inhibited by PGE2, whereas sphincter pressure is increased and esophageal contractions are induced by PGF2alpha. 3. Basal and stimulated gastric acid secretion is inhibited by PGE and its methyl analogues, but not by PGF, in a dose-related, nonselective manner. Oral administration of PGE methyl analogues may be an effective mode of therapy in peptic ulcer disease. 4. The prostaglandins reduce absorption and induce secretion of electrolytes and water in the jejunum and ileum but not in the colon. This secretory effect has been implicated in certain pathologic conditions. 5. The prostaglandins appear to be vasodilators of the hepatic circulation. Prostaglandin E contracts the gall bladder, relaxes the sphincter of Oddi and inhibits isosmotic fluid transport. 6. Pancreatic secretion and insulin release are inhibited by the prostaglandins in vivo and secretion is stimulated in vitro. The actual role of the prostaglandins in insulin release is not known.