Motility of the small intestine: a look ahead

Motility of the gastrointestinal tract has become an important discipline of gastroenterology. In this paper we review important observations made during the early development of this discipline, note the current level of knowledge, and look ahead to some of the questions we believe will be addressed in the near future. Is the slow wave the action potential equivalent of the longitudinal muscle layer? How does the migrating action potential complex interrelate with the migrating myoelectric complex--are they two separate complexes under different control mechanisms? How do the myenteric plexus neurons relate to these complexes? Does the muscularis mucosa control the contraction and relaxation of the villous tips? Is there a finite area in the small intestine that can function as the pacemaker? How important are substances within the lumen in controlling motility? Finally, we emphasize the importance of structure and function of the plexus neurons in motility studies. We also stress the importance of collaboration and a multidisciplinary approach for future understanding of the mechanisms of the small intestine in health and disease.