Citrulline stimulates muscle protein synthesis in the post-absorptive state in healthy people fed a low-protein diet - A pilot study

Marion Jourdan, K Sreekumaran Nair, Rickey E. Carter, Jill Schimke, G. Charles Ford, Julie Marc, Christian Aussel, Luc Cynober

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

Background & aims: Amino acid (AA) availability is critical to maintain protein homeostasis and reduced protein intake causes a decline in protein synthesis. Citrulline, an amino acid metabolite, has been reported to stimulate muscle protein synthesis in malnourished rats. Methods: To determine whether citrulline stimulates muscle protein synthesis in healthy adults while on a low-protein diet, we studied 8 healthy participants twice in a cross-over study design. Following a 3-days of low-protein intake, either citrulline or a non-essential AA mixture (NEAA) was given orally as small boluses over the course of 8h. [ring-<sup>13</sup>C<inf>6</inf>] phenylalanine and [<sup>15</sup>N] tyrosine were administered as tracers to assess protein metabolism. Fractional synthesis rates (FSR) of muscle proteins were measured using phenylalanine enrichment in muscle tissue fluid as the precursor pool. Results: FSR of mixed muscle protein was higher during the administration of citrulline than during NEAA (NEAA: 0.049±0.005; citrulline: 0.060±0.006; P=0.03), while muscle mitochondrial protein FSR and whole-body protein turnover were not different between the studies. Citrulline administration increased arginine and ornithine plasma concentrations without any effect on glucose, insulin, C-peptide, and IGF-1 levels. Citrulline administration did not promote mitochondria protein synthesis, transcripts, or citrate synthesis. Conclusions: Citrulline ingestion enhances mixed muscle protein synthesis in healthy participants on 3-day low-protein intake. This anabolic action of citrulline appears to be independent of insulin action and may offer potential clinical application in conditions involving low amino acid intake.

Original languageEnglish (US)
Pages (from-to)449-456
Number of pages8
JournalClinical Nutrition
Volume34
Issue number3
DOIs
StatePublished - Jun 1 2015

Keywords

  • Citrulline
  • Muscle
  • Phenylalanine
  • Protein synthesis

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine
  • Nutrition and Dietetics

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