The single-biopsy approach in determining protein synthesis in human slow-turning-over tissue: use of flood-primed, continuous infusion of amino acid tracers

Muscle protein synthesis (MPS) rate is determined conventionally by obtaining two or more tissue biopsies during a primed, continuous infusion of a stable isotopically labeled amino acid. The purpose of the present study was to test whether tracer priming given as a flooding dose, thereby securing a...

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Bibliographic Details
Published in:American journal of physiology: endocrinology and metabolism 2014-06, Vol.306 (11), p.E1330-E1339
Main Authors: Holm, Lars, Reitelseder, Søren, Dideriksen, Kasper, Nielsen, Rie H, Bülow, Jacob, Kjaer, Michael
Format: Article
Language:English
Subjects:
Algorithms
Amino acids
Amino Acids - chemistry
Biopsy
Biopsy - methods
Collagen - biosynthesis
Collagen - genetics
Connective Tissue - chemistry
Connective Tissue - metabolism
Data Interpretation, Statistical
Humans
Infusions, Intravenous
Keto Acids - blood
Leucine - analysis
Leucine - metabolism
Male
Muscle Proteins - biosynthesis
Muscle, Skeletal - chemistry
Muscle, Skeletal - metabolism
Myofibrils - metabolism
Phenylalanine - blood
Physiology
Protein Biosynthesis - physiology
Protein synthesis
Protocol
Radioactive Tracers
Tissues
Young Adult
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Summary:Muscle protein synthesis (MPS) rate is determined conventionally by obtaining two or more tissue biopsies during a primed, continuous infusion of a stable isotopically labeled amino acid. The purpose of the present study was to test whether tracer priming given as a flooding dose, thereby securing an instantaneous labeling of the tissue pools of free tracee amino acids, followed by a continuous infusion of the same tracer to maintain tracer isotopic steady state, could be used to determine the MPS rate over a prolonged period of time by obtaining only a single tissue biopsy. We showed that the tracer from the flood prime appeared immediately in the muscle free pool of amino acids and that this abundance could be kept constant by a subsequent continuous infusion of the tracer. When using phenylalanine as tracer, the flood-primed, continuous infusion protocol does not stimulate the MPS rate per se. In conclusion, the flood-primed, continuous infusion protocol using phenylalanine as tracer can validly be used to measure the protein synthesis rate in human in vivo experiments by obtaining only a single tissue biopsy after a prolonged infusion period.
ISSN:0193-1849
1522-1555
DOI:10.1152/ajpendo.00084.2014