Neural control of gastro-intestinal motility; events following receptor activation.

The motility of the mammalian gastro-intestinal tract is regulated by a number of neuronal systems. The postganglionic, intramural parts of these systems are characterized by their neurotransmitters as cholinergic, adrenergic and 'purinergic' nerves, respectively. The transmitter acetylcholine evokes contractions of the smooth muscle cell, whereas both noradrenalin and the transmitter from the 'purinergic' nerves, presumably ATP, induce relaxations of smooth muscles. Agents and actions which influence the neurohumoral transmission and the mechanisms underlying the effects induced by the transmitters in smooth muscle cells are reviewed.