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Mechanisms of postprandial protein accretion in human skeletal muscle. Insight from leucine and phenylalanine forearm kinetics.
J Clin Invest. 1996 Sep 15; 98(6):1361-72.JCI

Abstract

The relative role of protein synthesis and degradation in determining postprandial net protein deposition in human muscle is not known. To this aim, we studied forearm leucine and phenylalanine turnover by combining the arteriovenous catheterization with tracer infusions, before and following a 4 h administration of a mixed meal in normal volunteers. Forearm amino acid kinetics were assessed in both whole blood and plasma. Fasting forearm protein degradation exceeded synthesis (P < 0.01) using either tracer, indicating net muscle protein loss. The net negative forearm protein balance was quantitatively similar in whole blood and in plasma. After the meal, forearm proteolysis was suppressed (P < 0.05- < 0.03), while forearm protein synthesis was stimulated (P < 0.05- < 0.01). However, stimulation of protein synthesis was greater (P < 0.05- < 0.01) in whole blood (leucine data: +50.4 +/- 7.8 nmol/min x 100 ml of forearm; phenylalanine data: +30.4 +/- 11.6) than in plasma (leucine data: +17.8 +/- 5.6 nmol/min x 100 ml of forearm; phenylalanine data: +5.7 +/- 2.1). Consequently, the increment of net amino acid balance was approximately two to fourfold greater (P < 0.04- < 0.03) in whole blood than in plasma. In conclusion, meal ingestion stimulates forearm protein deposition through both enhanced protein synthesis and inhibited proteolysis. Plasma data underestimate net postprandial forearm protein synthesis, suggesting a key role of red blood cells and/or of blood mass in mediating mealenhanced protein accretion.

Authors+Show Affiliations

Department of Metabolic Diseases, University of Padova, Italy.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

8823301

Citation

Tessari, P, et al. "Mechanisms of Postprandial Protein Accretion in Human Skeletal Muscle. Insight From Leucine and Phenylalanine Forearm Kinetics." The Journal of Clinical Investigation, vol. 98, no. 6, 1996, pp. 1361-72.
Tessari P, Zanetti M, Barazzoni R, et al. Mechanisms of postprandial protein accretion in human skeletal muscle. Insight from leucine and phenylalanine forearm kinetics. J Clin Invest. 1996;98(6):1361-72.
Tessari, P., Zanetti, M., Barazzoni, R., Vettore, M., & Michielan, F. (1996). Mechanisms of postprandial protein accretion in human skeletal muscle. Insight from leucine and phenylalanine forearm kinetics. The Journal of Clinical Investigation, 98(6), 1361-72.
Tessari P, et al. Mechanisms of Postprandial Protein Accretion in Human Skeletal Muscle. Insight From Leucine and Phenylalanine Forearm Kinetics. J Clin Invest. 1996 Sep 15;98(6):1361-72. PubMed PMID: 8823301.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Mechanisms of postprandial protein accretion in human skeletal muscle. Insight from leucine and phenylalanine forearm kinetics. AU - Tessari,P, AU - Zanetti,M, AU - Barazzoni,R, AU - Vettore,M, AU - Michielan,F, PY - 1996/9/15/pubmed PY - 1996/9/15/medline PY - 1996/9/15/entrez SP - 1361 EP - 72 JF - The Journal of clinical investigation JO - J Clin Invest VL - 98 IS - 6 N2 - The relative role of protein synthesis and degradation in determining postprandial net protein deposition in human muscle is not known. To this aim, we studied forearm leucine and phenylalanine turnover by combining the arteriovenous catheterization with tracer infusions, before and following a 4 h administration of a mixed meal in normal volunteers. Forearm amino acid kinetics were assessed in both whole blood and plasma. Fasting forearm protein degradation exceeded synthesis (P < 0.01) using either tracer, indicating net muscle protein loss. The net negative forearm protein balance was quantitatively similar in whole blood and in plasma. After the meal, forearm proteolysis was suppressed (P < 0.05- < 0.03), while forearm protein synthesis was stimulated (P < 0.05- < 0.01). However, stimulation of protein synthesis was greater (P < 0.05- < 0.01) in whole blood (leucine data: +50.4 +/- 7.8 nmol/min x 100 ml of forearm; phenylalanine data: +30.4 +/- 11.6) than in plasma (leucine data: +17.8 +/- 5.6 nmol/min x 100 ml of forearm; phenylalanine data: +5.7 +/- 2.1). Consequently, the increment of net amino acid balance was approximately two to fourfold greater (P < 0.04- < 0.03) in whole blood than in plasma. In conclusion, meal ingestion stimulates forearm protein deposition through both enhanced protein synthesis and inhibited proteolysis. Plasma data underestimate net postprandial forearm protein synthesis, suggesting a key role of red blood cells and/or of blood mass in mediating mealenhanced protein accretion. SN - 0021-9738 UR - https://www.unboundmedicine.com/medline/citation/8823301/Mechanisms_of_postprandial_protein_accretion_in_human_skeletal_muscle__Insight_from_leucine_and_phenylalanine_forearm_kinetics_ L2 - https://doi.org/10.1172/JCI118923 DB - PRIME DP - Unbound Medicine ER -