Antroduodenal contractions were studied in rat preparations. Augmented duodenal contractions occurred spontaneously in coordination with antral contractions in normal and saline-pretreated preparations. The coordination did not occur when muscle layers and the myenteric plexus were transversely cut at the duodenum just anal to the gastroduodenal junction. In silent preparations, the coordinated contractions were produced by neostigmine or domperidone. When the antroduodenal junctional zone was pretreated with benzalkonium chloride, the augmented duodenal contractions did not occur spontaneously, and even after administration of neostigmine and domperidone although antral contractions occurred spontaneously. In these preparations, there were notably few myenteric neurons in the junctional zone, but the neurons were distributed normally in the areas where motility was recorded. The results suggest that myenteric neurons mediate antroduodenal coordinated contractions and that the coordination is modified by myenteric cholinergic excitatory and dopaminergic inhibitory pathways.</p
