5-Hydroxytryptophan modulates postprandial motor patterns of canine proximal small intestine

The aim of the study was to clarify whether 5-hydroxytryptophan (5-HTP) stimulates the postprandial motor pattern of the duodenum in a similar way as that of the adjacent jejunal segment in dogs. Computerized analysis of motor patterns recorded by closely spaced strain gauges focused on the temporal and spatial distribution of the contractions. Results indicate that 5-HTP increased the incidence and the length of the spread of contraction waves after both an acaloric and a nutrient meal in the duodenum as well as in the adjacent jejunal segment. Effects were more pronounced after the nutrient than after the acaloric meal. After the nutrient meal, but not after the acaloric meal, 5-HTP additionally enhanced the number of both duodenal and jejunal contractions per minute and increased the force of duodenal contractions. The acaloric meal induced significant differences in the motor patterns between the duodenum and the adjacent jejunum. 5-HTP abolished these differences owing to a relatively stronger stimulation of duodenal motility. 5-HTP did not affect gastric emptying of both meals. We conclude (i) that 5-HTP is a potent stimulator of propagated contractions both in the duodenum and the adjacent jejunal segment and (ii) that intestinal motor patterns can be regulated independently of gastric emptying.