scholarly journals Effects of dietary amino acid supplementation on measures of whole‐body and muscle protein metabolism in aged horses

2018 ◽  
Vol 103 (1) ◽  
pp. 283-294
Author(s):  
Christine M. Latham ◽  
Ashley L. Wagner ◽  
Kristine L. Urschel
Keyword(s):  
Amino Acid ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Whole Body ◽  
Amino Acid Supplementation ◽  
Acid Supplementation ◽  
Dietary Amino Acid ◽  
Muscle Protein Metabolism

scholarly journals Comprehensive assessment of post-prandial protein handling by the application of intrinsically labelled protein in vivo in human subjects

2021 ◽  
pp. 1-9
Author(s):  
Jorn Trommelen ◽  
Andrew M. Holwerda ◽  
Philippe J. M. Pinckaers ◽  
Luc J. C. van Loon
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Stable Isotope ◽  
Dietary Protein ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Human Subjects ◽  
Whole Body ◽  
Body Protein

All human tissues are in a constant state of remodelling, regulated by the balance between tissue protein synthesis and breakdown rates. It has been well-established that protein ingestion stimulates skeletal muscle and whole-body protein synthesis. Stable isotope-labelled amino acid methodologies are commonly applied to assess the various aspects of protein metabolism in vivo in human subjects. However, to achieve a more comprehensive assessment of post-prandial protein handling in vivo in human subjects, intravenous stable isotope-labelled amino acid infusions can be combined with the ingestion of intrinsically labelled protein and the collection of blood and muscle tissue samples. The combined application of ingesting intrinsically labelled protein with continuous intravenous stable isotope-labelled amino acid infusion allows the simultaneous assessment of protein digestion and amino acid absorption kinetics (e.g. release of dietary protein-derived amino acids into the circulation), whole-body protein metabolism (whole-body protein synthesis, breakdown and oxidation rates and net protein balance) and skeletal muscle metabolism (muscle protein fractional synthesis rates and dietary protein-derived amino acid incorporation into muscle protein). The purpose of this review is to provide an overview of the various aspects of post-prandial protein handling and metabolism with a focus on insights obtained from studies that have applied intrinsically labelled protein under a variety of conditions in different populations.

Leucine as a regulator of whole body and skeletal muscle protein metabolism in humans

1992 ◽  
Vol 263 (5) ◽  
pp. E928-E934 ◽  
Author(s):  
K. S. Nair ◽  
R. G. Schwartz ◽  
S. Welle
Keyword(s):  
Amino Acids ◽  
Protein Degradation ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Plasma Concentrations ◽  
Essential Amino Acids ◽  
Whole Body ◽  
Skeletal Muscle Protein ◽  
Muscle Protein Metabolism

Leucine has been proposed as an in vivo regulator of protein metabolism, although the evidence for this in humans remains inconclusive. To test this hypothesis, we infused either L-leucine (154 +/- 1 mumol.kg-1 x h-1) or saline intravenously in six healthy men in two separate studies. L-Leucine infusion increased plasma concentrations of leucine and alpha-ketoisocaproate from 112 +/- 6 and 38 +/- 3 mumol/l to 480 +/- 27 (P < 0.001) and 94 +/- 13 mumol/l (P < 0.001), respectively, without any significant change in circulating insulin or C peptide levels. Leucine infusion decreased plasma concentrations of several amino acids and decreased whole body valine flux and valine oxidation (using L-[1-13C]valine as a tracer) and phenylalanine flux (using [2H5]-phenylalanine as a tracer). According to arteriovenous differences across the leg, the net balance of phenylalanine, valine, and lysine shifted toward greater retention during leucine infusion, whereas alanine balance did not change. Valine release and phenylalanine release from the leg (estimated from the dilution of respective tracers) decreased, indicating inhibition of protein degradation by leucine infusion. We conclude that leucine decreases protein degradation in humans and that this decreased protein degradation during leucine infusion contributes to the decrease in plasma essential amino acids. This study suggests a potential role for leucine as a regulator of protein metabolism in humans.

scholarly journals Whole body creatine and protein kinetics in healthy men and women: effects of creatine and amino acid supplementation

Amino Acids ◽  
2015 ◽  
Vol 48 (3) ◽  
pp. 677-687 ◽  
Author(s):  
Satish C. Kalhan ◽  
Lourdes Gruca ◽  
Susan Marczewski ◽  
Carole Bennett ◽  
China Kummitha
Keyword(s):  
Amino Acid ◽  
Whole Body ◽  
Amino Acid Supplementation ◽  
Protein Kinetics ◽  
Men And Women ◽  
Healthy Men ◽  
Acid Supplementation

scholarly journals Human Skeletal Muscle Protein Metabolism Responses to Amino Acid Nutrition

2016 ◽  
Vol 7 (4) ◽  
pp. 828S-838S ◽  
Author(s):  
W Kyle Mitchell ◽  
Daniel J Wilkinson ◽  
Bethan E Phillips ◽  
Jonathan N Lund ◽  
Kenneth Smith ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Protein Metabolism ◽  
Human Skeletal Muscle ◽  
Muscle Protein ◽  
Skeletal Muscle Protein ◽  
Muscle Protein Metabolism
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