The effect of intraluminal tryptophan and phenylalanine on small intestinal motility in the conscious dog.

Abstract

SUMMARY1. The effect of D-and L-isomers of tryptophan and phenylalanine on fasting motor activity of canine jejunum were investigated.2. Only L-tryptophan had any effect on jejunal motility. The concentration of L-tryptophan required to elicit a motor effect in 50 % of animals was estimated at 28 mM.3. 50 mM-L-tryptophan stimulated jejunal motility after a latency of 4-5 + 0-7 min. The pattern of motility was similar to that evoked by feeding but continued for only 41+5 min and failed to disrupt the normal timing of the interdigestive migrating motor complex (m.m.c.). The duration of the subsequent phase II of the complex was, however, significantly reduced.4. Multiple infusion of L-tryptophan also failed to disrupt the timing of the m.m.c. 5. These data are consistent with the hypothesis that specific breakdown components of protein digestion are implicated in the stimulation of postprandial motor activity. The mechanisms involved in the motor response to L-tryptophan are discussed.

Motility changes induced by intraluminal FeSO4 in guinea pig jejunum

“…This is in agreement with our data showing that iron lowers the peristaltic threshold. In contrast, no amino acids tested, including l ‐phenylalanine, have been found to affect the migrating motor complex . In agreement with our data on decanoic acid, intra‐duodenal lipid infusion increases pressure waves in the human duodenum, an effect similar to the lowering of peristaltic threshold.…”

“…In contrast, no amino acids tested, including L-phenylalanine, have been found to affect the migrating motor complex. 45 In agreement with our data on decanoic acid, intra-duodenal lipid infusion increases pressure waves in the human duodenum 46 , an effect similar to the lowering of peristaltic threshold. Taken together, this suggests that iron, fatty acids, and amino acids are handled by different sensory mucosal mechanisms.…”

Different effects of casein and soyabean protein on gastric emptying of protein and small intestinal transit after spontaneous feeding of diets in rats

“…I). Transit velocity of the small intestinal contents is generally determined by intestinal motility, fluid secretion into the lumen, viscosity of the chyme, and some amino acids in the lumen (Bull et al 1985;Bouyssou et ul. 1988).…”

Effects of Intraduodenal Infusions of L-phenylalanine and L-glutamine on Antropyloroduodenal Motility and Plasma Cholecystokinin in Healthy Men

“…This is in line with earlier studies showing that aromatic amino acids modulate upper GI function including biliopancreatic secretion, upper intestinal motility and gastrin and gastric acid secretion. 18,[31][32][33][34][35][36] Whether the different secretory responses are related to different amino acids transport mechanisms or luminal amino acids receptors, however, requires further research. We also evaluated the effect of L-Phe and L-Gln on APD motility.…”