Second-, minute- and hour-metronomes of intestinal pacemakers.

1. Movements of the gastrointestinal tract are required for the digestion of food and the expulsion of waste products. 2. The present paper will discuss the nature of electrical rhythms underlying some intestinal motility patterns. 3. The rhythms are generated by pacemakers with cycle rates appropriate to controlling individual contractions, motor patternings or switching between different motor programmes. 4. Electrical rhythms are discussed with periods of the order of seconds, minutes and hours. 5. Particular discussion is centred on rhythms recorded from the small and large intestine of the mouse.