title: Effects of Intraduodenal Infusions of L-phenylalanine and L-glutamine on Antropyloroduodenal Motility and Plasma Cholecystokinin in Healthy Men.
abstract: Dietary proteins have potent eating-inhibitory and glucose-lowering effects, which may be mediated via effects of amino acids on gastrointestinal hormone and motor function, although little information is available. We have now evaluated the effects of L-phenylalanine (L-Phe) and L-glutamine (L-Gln) on antropyloroduodenal motility and plasma cholecystokinin (CCK) concen-trations.
  
  
  
  Two double-blind, 3-way cross-over studies were performed, each including 10 healthy, normal-weight men. We determined the antropyloroduodenal motor and plasma CCK responses to 90-minute intraduodenal infusions of L-Phe (study A) or L-Gln (study B), each at 0.15 kcal/min (total 13.5 kcal), or 0.45 kcal/min (total 40.5 kcal), or saline (control), in randomized fashion.
  
  
  
  Intraduodenal L-Phe at 0.45 kcal/min, but not at 0.15 kcal/min, suppressed antral (P < 0.01), and stimulated phasic (P < 0.01), but not tonic, pyloric, or duodenal pressures, while L-Phe at both 0.15 kcal/min and 0.45 kcal/min stimulated plasma CCK. In contrast, L-Gln had no effect on antral, duodenal or pyloric pressures, or plasma CCK.
  
  
  
  Intraduodenal infusions of L-Phe and L-Gln, in doses of 0.15 kcal/min and 0.45 kcal/min for 90 minutes, have different effects on antropyloroduodenal motility and CCK in normal-weight men. The modulation of antral and pyloric pressures and CCK may contribute to the eating-inhibitory effects of oral L-Phe, possibly through the slowing of gastric emptying.
authors.affiliation: Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Robert E
authors.identifier: 0000-0001-7884-5036
authors.initials: RE
authors.lastname: Steinert
authors.affiliation: Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia.
authors.forename: Maria F
authors.identifier: 0000-0002-3498-3274
authors.initials: MF
authors.lastname: Landrock
authors.affiliation: Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia.|NHMRC Center of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia.
authors.forename: Michael
authors.identifier: 0000-0002-3067-7157
authors.initials: M
authors.lastname: Horowitz
authors.affiliation: Discipline of Medicine, The University of Adelaide, Royal Adelaide Hospital, Adelaide, Australia.|NHMRC Center of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia.
authors.forename: Christine
authors.identifier: 0000-0001-6848-0125
authors.initials: C
authors.lastname: Feinle-Bisset
keywords: Amino acids; Eating; Gastrointestinal hormones; Gastrointestinal motility; Humans