The Kinetics of Amino Acid Absorption and Alteration of Plasma Composition of Free Amino Acids After Intestinal Perfusion of Amino Acid Mixtures

Adibi, Siamak A.; Gray, Seymour J.; Menden, E.

doi:10.1093/ajcn/20.1.24

Cited by 100 publications

(43 citation statements)

References 14 publications

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“…It is pertinent to note that the rises in luminal concentrations of free amino acids after the meal were modest. In situations when the intestinal mucosa is presented with higher concentrations of free amino acids (3,5,(13)(14)(15), there may be changes in intracellular concentrations. DISCUSSION Previous studies have suggested that there is mixing of exogenous and endogenous proteins in the gut lumen.…”

Section: Methodsmentioning

confidence: 99%

“…The plasma studies fail to reveal any evidence of the influx of free amino acids from the gut into the periphery when protein is excluded from the meal. (3,5,(13)(14)(15), the interaction between the amino acids when they are presented to intestinal mucosa (3,13), and the differences in rates of release of amino acids from the protein undergoing enzymatic hydrolysis (18 (18,19).…”

Section: Methodsmentioning

confidence: 99%

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Protein Digestion in Human Intestine as Reflected in Luminal, Mucosal, and Plasma Amino Acid Concentrations after Meals

Adibi¹,

Mercer²

1973

J. Clin. Invest.

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357

162

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A B S T R A C T Normal human volunteers were intubated with either aspiration tubes or a biopsy capsule placed in the small intestine. The subjects were then fed a test meal containing 50 g of purified bovine serum albumin which served as the model dietary protein.Electrophoretic analysis of intestinal fluids showed that for at least 4 h the fed albumin was detectable in jejunal and ileal fluids. On separate occasions, subjects were fed the same meal without the protein. No protein was detected in intestinal fluids when the protein-free meal was fed. After the protein-rich meal, total concentrations of measured free and peptide amino acids rose from 3.21 to 29.29, and 15.94 to 117.97 ,umol/ml, respectively, (P values <0.02) in the jejunum. Similarly, total concentrations of measured free and peptide amino acids rose from 5.45 to 19.74, and 13.59 to 65.39, respectively, (P values < 0.05) in the ileum. In contrast, concentrations of free and peptide amino acids in intestinal fluids did not increase after the protein-free meal. While intracellular concentrations of amino acids in the jejunal mucosa did not show significant changes, plasma concentrations of each individual free amino acid were increased after the protein-rich meal and were either decreased or unaltered after the proteinfree meal. The amino acid composition of the fed protein was reflected in the increases in intraluminal and plasma concentrations of individual amino acids after the protein-rich meal. It is concluded that after the ingestion of a test meal containing a substantial amount of protein which is within the usual range of dietary

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Protein Digestion in Human Intestine as Reflected in Luminal, Mucosal, and Plasma Amino Acid Concentrations after Meals

Adibi¹,

Mercer²

1973

J. Clin. Invest.

Self Cite

357

162

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show abstract

“…Thcy suggest that interactions between amino acids, involving inhibition or stimulation of transport, are important in the absorption of mixtures in vivo (Gitler & Martinez-Rojas, 1964;Holdsworth, 1972). Adibi, Gray & Menden (1967) studied absorption of equimolar mixtures of eighteen amino acids by intestinal perfusion in man, Individual absorption rates varied widely. T h e most rapidly absorbed were methionine, leucine, isoleucine and valine, whereas glycine was absorbed comparatively slowly.…”

Section: Absorption Of Amino Acid Mixturesmentioning

confidence: 99%

Intestinal absorption of amino acids and peptides

Matthews

1972

Proc. Nutr. Soc.

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“…Studies of the intestinal absorption of free amino acids and dipeptides in human intestine (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13) have suggested that mucosal uptake of these substrates is mediated by carrier systems located on the brush border membrane. Furthermore, there appear to be separate carrier systems for free amino acids and dipeptides (6,12).…”

Section: Introductionmentioning

confidence: 99%

Evidence for two different modes of tripeptide disappearance in human intestine. Uptake by peptide carrier systems and hydrolysis by peptide hydrolases.

Adibi¹,

Morse²,

Masilamani³

et al. 1975

J. Clin. Invest.

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A B S T R A C T The intestinal fate of two tripeptides (triglycine and trileucine). which differ markedly in solubility and molecular weight, have been investigated by jejunal perfusion in healthy human volunteers. Rates of glycine or leucine uptake from test solutions containing triglycine or trileucine were greater than from test solutions containing corresponding amounts of free glycine or free leucine, respectively. The rate of glycine uptake from a 100 mM triglycine solution was greater than that from a 150 mM diglycine solution. At each infused load of triglycine (e.g., 1,000 imol/min) the rates (micromoles/minute per 30 cm) of either triglycine disappearance (810±40) or glycine absorption (2,208±+122) were markedly greater than the luminal accumulation rates of either diglycine (56±10) or free glycine (110±18). The luminal accumulation rate of free leucine during infusion of a 5 mM trileucine solution was over threefold greater than that of free glycine during the infusion of a 5 mM triglycine solution. Luminal fluid exhibited no hydrolytic activity against triglycine, but contained some activity against trileucine. Saturation of free amino acid carrier system with a large load of leucine did not affect glycine absorption rate from a triglycine test solution, but isoleucine markedly inhibited the uptake of leucine from a trileucine solution. When the carrier system for dipeptides was saturated with a large amount of glycyl-A preliminary account of this work has been previously published (1974. Gastroenterology. 66: 657) leucine, the disappearance rate of triglycine was considerably reduced while that of trileucine remained unaffected. After addition of glycylleucine to tripeptide solutions, there was a minimal increase in the luminal accumulation of diglycine, while dileucine accumulation was increased by 62-fold.These studies suggest that the modes of intestinal disappearance of the above two tripeptides are different. Triglycine is taken up intact by human jejunum; this uptake is mediated totally or partially by the carrier system which also transports dipeptides. In contrast, trileucine is hydrolyzed to leucine and dileucine mostly on the cell surface and a small fraction is hydrolyzed in the gut lumen; these hydrolytic products are then taken up by the free amino acid and dipeptide carrier systems, respectively.

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The Kinetics of Amino Acid Absorption and Alteration of Plasma Composition of Free Amino Acids After Intestinal Perfusion of Amino Acid Mixtures

Cited by 100 publications

References 14 publications

Protein Digestion in Human Intestine as Reflected in Luminal, Mucosal, and Plasma Amino Acid Concentrations after Meals

Protein Digestion in Human Intestine as Reflected in Luminal, Mucosal, and Plasma Amino Acid Concentrations after Meals

Intestinal absorption of amino acids and peptides

Evidence for two different modes of tripeptide disappearance in human intestine. Uptake by peptide carrier systems and hydrolysis by peptide hydrolases.

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