Validation of a single biopsy approach and bolus protein feeding to determine myofibrillar protein synthesis in stable isotope tracer studies in humans

被引：59

作者：

Phillips S.M. ^{[1
]}

Burd N.A. ^{[1
]}

West D.W. ^{[1
]}

Rerecich T. ^{[1
]}

Prior T. ^{[1
]}

Baker S.K. ^{[2
]}

机构：

[1] Exercise Metabolism Research Group, Department of Kinesiology, McMaster University, Hamilton, ON

[2] Michael G. DeGroote School of Medicine, Department of Neurology, McMaster University, Hamilton, ON

来源：

Nutrition & Metabolism | / 8卷 / 1期

基金：

加拿大自然科学与工程研究理事会;

关键词：

Whey Protein; Muscle Protein; Muscle Protein Synthesis; Precursor Pool; Tracer Enrichment;

D O I：

10.1186/1743-7075-8-15

中图分类号：

学科分类号：

摘要：

Background: Minimizing the number of muscle biopsies has important methodological implications and minimizes subject discomfort during a stable isotope amino acid infusion. We aimed to determine the reliability of obtaining a single muscle biopsy for the calculation of muscle protein fractional synthetic rate (FSR) as well as the amount of incorporation time necessary to obtain that biopsy after initiating a stable isotope infusion (Study 1). The calculation of muscle protein FSR requires tracer steady-state during the stable isotope infusion. Therefore, a second aim was to examine if steady-state conditions are compromised in the precursor pools (plasma free or muscle intracellular [IC]) after ingestion of a tracer enriched protein drink and after resistance exercise (Study 2). Methods. Sixteen men (23 3 years; BMI = 23.8 2.2 kg/m2, means SD) were randomized to perform Study 1 or Study 2 (n = 8, per study). Subjects received a primed, constant infusion of L-[ring- 13C6]phenylalanine coupled with muscle biopsies of the vastus lateralis to measure rates of myofibrillar protein synthesis (MPS). Subjects in Study 2 were fed 25 g of whey protein immediately after an acute bout of unilateral resistance exercise. Results: There was no difference (P = 0.3) in rates of MPS determined using the steady-state precursor-product equation and determination of tracer incorporation between sequential biopsies 150 min apart or using plasma protein as the baseline enrichment, provided the infusion length was sufficient (230 0.3 min). We also found that adding a modest amount of tracer (4% enriched), calculated based on the measured phenylalanine content of the protein (3.5%) in the drink, did not compromise steady-state conditions (slope of the enrichment curve not different from zero) in the plasma free or, more importantly, the IC pool (both P > 0.05). Conclusions: These data demonstrate that the single biopsy approach yields comparable rates of muscle protein synthesis, provided a longer incorporation time is utilized, to that seen with a traditional two biopsy approach. In addition, we demonstrate that enriching protein-containing drinks with tracer does not disturb isotopic steady-state and thus both are reliable techniques to determine rates of MPS in humans. © 2011 Burd et al; licensee BioMed Central Ltd.

引用

共 28 条

[1]

Rennie M.J., Smith K., Watt P.W., Measurement of human tissue protein synthesis: An optimal approach, The American Journal of Physiology, 266, pp. 5298-307, (1994)

[2]

Wolfe R.R., Chinkes D.L., Isotope Tracers in Metabolic Research: Principles and Practice of Kinetic Analysis, (2005)

[3]

Smith G.I., Villareal D.T., Lambert C.P., Reeds D.N., Mohammed B.S., Mittendorfer B., Timing of the initial muscle biopsy does not affect the measured muscle protein fractional synthesis rate during basal, postabsorptive conditions, J Appl Physiol, 108, pp. 363-368, (2010)

[4]

Burd N.A., Holwerda A.M., Selby K.C., West D.W., Staples A.W., Cain N.E., Cashaback J.G., Potvin J.R., Baker S.K., Phillips S.M., Resistance exercise volume affects myofibrillar protein synthesis and anabolic signalling molecule phosphorylation in young men, The Journal of Physiology, 588, pp. 3119-3130, (2010)

[5]

Burd N.A., West D.W., Staples A.W., Atherton P.J., Baker J.M., Moore D.R., Holwerda A.M., Parise G., Rennie M.J., Baker S.K., Phillips S.M., Low-load high volume resistance exercise stimulates muscle protein synthesis more than high-load low volume resistance exercise in young men, PLoS ONE, 5, (2010)

[6]

West D.W., Kujbida G.W., Moore D.R., Atherton P., Burd N.A., Padzik J.P., De Lisio M., Tang J.E., Parise G., Rennie M.J., Et al., Resistance exercise-induced increases in putative anabolic hormones do not enhance muscle protein synthesis or intracellular signalling in young men, The Journal of Physiology, 587, pp. 5239-5247, (2009)

[7]

Miller B.F., Olesen J.L., Hansen M., Dossing S., Crameri R.M., Welling R.J., Langberg H., Flyvbjerg A., Kjaer M., Babraj J.A., Smith K., Rennie M.J., Coordinated collagen and muscle protein synthesis in human patella tendon and quadriceps muscle after exercise, Journal of Physiology, 567, 3, pp. 1021-1033, (2005)

[8]

Tang J.E., Moore D.R., Kujbida G.W., Tarnopolsky M.A., Phillips S.M., Ingestion of whey hydrolysate, casein, or soy protein isolate: Effects on mixed muscle protein synthesis at rest and following resistance exercise in young men, J Appl Physiol, 107, pp. 987-992, (2009)

[9]

Heys S.D., McNurlan M.A., Park K.G.M., Milne E., Garlick P.J., Baseline measurements for stable isotope studies: An alternative to biopsy, Biomedical and Environmental Mass Spectrometry, 19, 3, pp. 176-178, (1990)

[10]

Moore D.R., Robinson M.J., Fry J.L., Tang J.E., Glover E.I., Wilkinson S.B., Prior T., Tarnopolsky M.A., Phillips S.M., Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men, The American Journal of Clinical Nutrition, 89, pp. 161-168, (2009)

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