[Effect of serotonin on the myoelectrical activity of the body of the stomach, the pyloric sphincter and duodenum].

8-10 mg/kg serotonin augmented the AP amplitude in the duodenum and reduced it in the stomach and pyloric sphincter in rabbits, the burst frequency in the duodenum smooth muscles being much higher than in the latters. The amount of APs in each burst increased after serotonin administration in the duodenum and decreased in the stomach and pyloric sphincter, the activating effect of serotonin on the duodenum smooth muscles preceding its inhibitory effect on the latter's smooth muscles. The higher sensitivity to serotonin seems to be due to a higher concentration of endogenous serotonin in the duodenum tissue.