Role of prostaglandins in regulating gastric motility.

Muscles of the stomach possess the ability to synthesize several prostaglandins. These compounds function as local regulatory agents by influencing the motor performance of the muscle cells. In the distal stomach the dominant effect of endogenous prostaglandins is to decrease the amplitude of contractions and decrease the ability of the muscles to respond to excitatory stimuli. Prostaglandins also have a chronotropic role in the distal stomach, and they are responsible for the frequency effect of gastrin pentapeptide. In the proximal stomach prostaglandins have an opposite role; they promote tonic contraction. Because of the diverse effects of prostaglandins, they probably have complicated effects on gastric motility. In general, emptying of solids should be retarded by endogenous prostaglandins, whereas emptying of fluids may be facilitated by these compounds. Overproduction of prostaglandins may produce abnormal motility patterns and affect gastric emptying. A case of gastric pseudoobstruction apparently involving prostaglandins is discussed.