Decrease in human quadriceps muscle protein turnover consequent upon leg immobilization

1987 ◽  
Vol 72 (4) ◽  
pp. 503-509 ◽  
Author(s):  
J. N. A. Gibson ◽  
D. Halliday ◽  
W. L. Morrison ◽  
P. J. Stoward ◽  
G. A. Hornsby ◽  
...  
Keyword(s):  
Protein Turnover ◽  
Muscle Protein ◽  
Fibre Diameter ◽  
Quadriceps Muscle ◽  
Fibre Volume ◽  
Type I ◽  
Protein Breakdown ◽  
Muscle Protein Turnover ◽  
Muscle Protein Breakdown ◽  
Synthetic Rate

1. Quadriceps muscle protein turnover was assessed in the post-absorptive state in six men immediately after the end of unilateral leg immobilization (37 ± 4 days) in a plaster cast after tibial fracture. A primed-constant intravenous infusion of l-[1-13C]leucine was administered over 7 h. Quadriceps needle biopsies, taken bilaterally at the end of the infusion, were analysed for muscle protein leucine enrichment with 13C. 2. Quadriceps muscle protein synthetic rate, calculated from the fractional incorporation of [13C]leucine into protein compared with the average enrichment of blood α-ketoisocaproate, was 0.046 ±0.012%/h in the uninjured leg, but was only 0.034 ±0.007%/h in the quadriceps of the previously fractured leg (P > 0.05, means ± sd). 3. Muscle RNA activity (i.e. protein synthetic rate per RNA) fell from 0.27 ±0.08 μg of protein synthesized h−1 μg−1 of RNA in the control leg to 0.14 ±0.03 μg of protein synthesized h−1 μg−1 of RNA in the immobilized leg (P > 0.02). 4. Immobilization was associated with a significant atrophy of type I muscle fibres (mean diameter 69.5 ±21 μm immobilized, 81.1 ±18 μm control, P > 0.05), but no significant change occurred in type II fibre diameter. Mean quadriceps fibre volume calculated from the values for fibre diameter and percentage of each fibre type, was smaller in the injured leg by 10.6%; this value was near to the calculated difference in muscle thigh volume (calculated from thigh circumference and skin-fold thickness) which was less by 8.3%. 5. From estimated mean daily values for quadriceps protein synthetic rate (1.65 ±0.44%/day in the control legs and 1.22±0.28%/day in the injured legs) and change in fibre volume, mean daily muscle protein breakdown rates were calculated as 1.65%/ day and 1.53%/day respectively, suggesting that muscle protein breakdown was not enhanced and may have fallen. 6. The results suggest a decrease in muscle protein turnover during limb immobilization in man, with the decrement in muscle mass being due mainly to a substantial (25%) depression of muscle protein synthesis.

Exercise training and protein metabolism: influences of contraction, protein intake, and sex-based differences

2009 ◽  
Vol 106 (5) ◽  
pp. 1692-1701 ◽  
Author(s):  
Nicholas A. Burd ◽  
Jason E. Tang ◽  
Daniel R. Moore ◽  
Stuart M. Phillips
Keyword(s):  
Signaling Pathways ◽  
Protein Turnover ◽  
Muscle Hypertrophy ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Protein Breakdown ◽  
Muscle Protein Turnover ◽  
Muscle Protein Breakdown ◽  
Response To Exercise ◽  
Net Protein

Muscle contraction during exercise, whether resistive or endurance in nature, has profound affects on muscle protein turnover that can persist for up to 72 h. It is well established that feeding during the postexercise period is required to bring about a positive net protein balance (muscle protein synthesis − muscle protein breakdown). There is mounting evidence that the timing of ingestion and the protein source during recovery independently regulate the protein synthetic response and influence the extent of muscle hypertrophy. Minor differences in muscle protein turnover appear to exist in young men and women; however, with aging there may be more substantial sex-based differences in response to both feeding and resistance exercise. The recognition of anabolic signaling pathways and molecules are also enhancing our understanding of the regulation of protein turnover following exercise perturbations. In this review we summarize the current understanding of muscle protein turnover in response to exercise and feeding and highlight potential sex-based dimorphisms. Furthermore, we examine the underlying anabolic signaling pathways and molecules that regulate these processes.

Effect of exercise and recovery on muscle protein synthesis in human subjects

1990 ◽  
Vol 259 (4) ◽  
pp. E470-E476 ◽  
Author(s):  
F. Carraro ◽  
C. A. Stuart ◽  
W. H. Hartl ◽  
J. Rosenblatt ◽  
R. R. Wolfe
Keyword(s):  
Protein Synthesis ◽  
Aerobic Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Nitrogen Excretion ◽  
Control Group ◽  
Protein Breakdown ◽  
Muscle Protein Breakdown ◽  
Synthetic Rate ◽  
Fractional Synthetic Rate

Previous studies using indirect means to assess the response of protein metabolism to exercise have led to conflicting conclusions. Therefore, in this study we have measured the rate of muscle protein synthesis in normal volunteers at rest, at the end of 4 h of aerobic exercise (40% maximal O2 consumption), and after 4 h of recovery by determining directly the rate of incorporation of 1,2-[13C]leucine into muscle. The rate of muscle protein breakdown was assessed by 3-methylhistidine (3-MH) excretion, and total urinary nitrogen excretion was also measured. There was an insignificant increase in 3-MH excretion in exercise of 37% and a significant increase (P less than 0.05) of 85% during 4 h of recovery from exercise (0.079 +/- 0.008 vs. 0.147 +/- 0.0338 mumol.kg-1.min-1 for rest and recovery from exercise, respectively). Nonetheless, there was no effect of exercise on total nitrogen excretion. Muscle fractional synthetic rate was not different in the exercise vs. the control group at the end of exercise (0.0417 +/- 0.004 vs. 0.0477 +/- 0.010%/h for exercise vs. control), but there was a significant increase in fractional synthetic rate in the exercise group during the recovery period (0.0821 +/- 0.006 vs. 0.0654 +/- 0.012%/h for exercise vs. control, P less than 0.05). Thus we conclude that although aerobic exercise may stimulate muscle protein breakdown, this does not result in a significant depletion of muscle mass because muscle protein synthesis is stimulated in recovery.

Creatine supplementation has no effect on human muscle protein turnover at rest in the postabsorptive or fed states

2003 ◽  
Vol 284 (4) ◽  
pp. E764-E770 ◽  
Author(s):  
Magali Louis ◽  
Jacques R. Poortmans ◽  
Marc Francaux ◽  
Eric Hultman ◽  
Jacques Berré ◽  
...  
Keyword(s):  
Muscle Mass ◽  
Muscle Protein ◽  
Creatine Supplementation ◽  
Quadriceps Muscle ◽  
Protein Breakdown ◽  
Fed State ◽  
Muscle Protein Breakdown ◽  
Before And After ◽  
Total Creatine ◽  
Myofibrillar Protein Synthesis

Dietary creatine supplementation is associated with increases in muscle mass, but the mechanism is unknown. We tested the hypothesis that creatine supplementation enhanced myofibrillar protein synthesis (MPS) and diminished muscle protein breakdown (MPB) in the fed state. Six healthy men (26 ± 7 yr, body mass index 22 ± 4 kg/m2) were studied twice, 2–4 wk apart, before and after ingestion of creatine (21 g/day, 5 days). We carried out two sets of measurements within 5.5 h of both MPS (by incorporation of [1-13C]leucine in quadriceps muscle) and MPB (as dilution of [1-13C]leucine or [2H5]phenylalanine across the forearm); for the first 3 h, the subjects were postabsorptive but thereafter were fed orally (0.3 g maltodextrin and 0.083 g protein · kg body wt−1 · h−1). Creatine supplementation increased muscle total creatine by ∼30% ( P < 0.01). Feeding had significant effects, doubling MPS ( P < 0.001) and depressing MPB by ∼40% ( P < 0.026), but creatine had no effect on turnover in the postabsorptive or fed states. Thus any increase in muscle mass accompanying creatine supplementation must be associated with increased physical activity.

Measurement of muscle protein degradation in live mice by accumulation of bestatin-induced peptides

1997 ◽  
Vol 273 (6) ◽  
pp. E1149-E1157 ◽  
Author(s):  
Violeta Botbol ◽  
Oscar A. Scornik
Keyword(s):  
Protein Degradation ◽  
Protein Turnover ◽  
Skeletal Muscles ◽  
Muscle Protein ◽  
Cellular Proteins ◽  
Protein Breakdown ◽  
Maximum Accumulation ◽  
Muscle Protein Breakdown ◽  
Muscle Protein Degradation ◽  
Acute Changes

Bestatin, an aminopeptidase inhibitor, permits the degradation of cellular proteins to di- and tripeptides but interferes with the further breakdown of these peptides to amino acids. We propose to measure instant rates of protein degradation in skeletal muscles of intact mice by the accumulation of bestatin-induced intermediates. Muscle protein was labeled by injection ofl-[guanidino-14C]arginine; 3 days later, maximum accumulation of intermediates was measured in abdominal wall muscles 10 min after the intravenous injection of 5 mg of bestatin. The peptides were partially purified and hydrolyzed in 6 N HCl, and the radioactivity in peptide-derived arginine was determined, after conversion to14CO2by treatment with arginase and urease. The measurement of bestatin-induced intermediates provides a unique tool for studying acute changes in muscle protein turnover in live mice. We observed a 62% increase in muscle protein breakdown after a 16-h fast, which was reversed by refeeding for 3.5 h, and a 38% increase after 3 days of protein depletion.

scholarly journals Combined in vivo muscle mass, muscle protein synthesis and muscle protein breakdown measurement: a ‘Combined Oral Stable Isotope Assessment of Muscle (COSIAM)’ approach

GeroScience ◽  
2021 ◽  
Author(s):  
Jessica Cegielski ◽  
Daniel J. Wilkinson ◽  
Matthew S. Brook ◽  
Catherine Boereboom ◽  
Bethan E. Phillips ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Stable Isotope ◽  
Muscle Mass ◽  
Protein Turnover ◽  
Skeletal Muscle Mass ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Protein Breakdown ◽  
Muscle Protein Breakdown

AbstractOptimising approaches for measuring skeletal muscle mass and turnover that are widely applicable, minimally invasive and cost effective is crucial in furthering research into sarcopenia and cachexia. Traditional approaches for measurement of muscle protein turnover require infusion of expensive, sterile, isotopically labelled tracers which limits the applicability of these approaches in certain populations (e.g. clinical, frail elderly). To concurrently quantify skeletal muscle mass and muscle protein turnover i.e. muscle protein synthesis (MPS) and muscle protein breakdown (MPB), in elderly human volunteers using stable-isotope labelled tracers i.e. Methyl-[D3]-creatine (D3-Cr), deuterium oxide (D2O), and Methyl-[D3]-3-methylhistidine (D3-3MH), to measure muscle mass, MPS and MPB, respectively. We recruited 10 older males (71 ± 4 y, BMI: 25 ± 4 kg.m2, mean ± SD) into a 4-day study, with DXA and consumption of D2O and D3-Cr tracers on day 1. D3-3MH was consumed on day 3, 24 h prior to returning to the lab. From urine, saliva and blood samples, and a single muscle biopsy (vastus lateralis), we determined muscle mass, MPS and MPB. D3-Cr derived muscle mass was positively correlated to appendicular fat-free mass (AFFM) estimated by DXA (r = 0.69, P = 0.027). Rates of cumulative myofibrillar MPS over 3 days were 0.072%/h (95% CI, 0.064 to 0.081%/h). Whole-body MPB over 6 h was 0.052 (95% CI, 0.038 to 0.067). These rates were similar to previous literature. We demonstrate the potential for D3-Cr to be used alongside D2O and D3-3MH for concurrent measurement of muscle mass, MPS, and MPB using a minimally invasive design, applicable for clinical and frail populations.

scholarly journals A comparison of methods for the measurement of protein turnover in vivo

1979 ◽  
Vol 184 (2) ◽  
pp. 473-476 ◽  
Author(s):  
M L MacDonald ◽  
S L Augustine ◽  
T L Burk ◽  
R W Swick
Keyword(s):  
Amino Acids ◽  
Steady State ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Comparison Of Methods ◽  
Ornithine Aminotransferase ◽  
Protein Breakdown ◽  
Muscle Protein Breakdown ◽  
Fractional Rate

Steady-state rates of turnover of two single proteins were measured in vivo by two independent methods. The fractional rate of synthesis of liver ornithine aminotransferase, measured by a continuous infusion of L-[2,6-3H]tyrosine, was 0.42 day-1, whereas in the same animals the fractional rate of degradation measured by loss of radioactivity from amino acids labelled via [14C]bicarbonate was 0.40 day-1. The agreement between methods confirms the reliability of each method for the study of hepatic protein turnover. In contrast, [14C]bicarbonate-labelled amino acids are extensively reutilized in muscle, and are therefore unsuitable for measuring rates of muscle protein breakdown.

Model to assess muscle protein turnover: domain of validity using amino acyl-tRNA vs. surrogate measures of precursor pool

2003 ◽  
Vol 285 (5) ◽  
pp. E1142-E1149 ◽  
Author(s):  
Gianna Toffolo ◽  
Robert Albright ◽  
Michael Joyner ◽  
Niki Dietz ◽  
Claudio Cobelli ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Compartment Model ◽  
Tissue Fluid ◽  
Protein Breakdown ◽  
Muscle Protein Turnover ◽  
Three Compartment Model ◽  
Surrogate Measures ◽  
Domain Of Validity

Current models to measure protein turnover across muscle bed are based on many surrogate measures of amino acyl-tRNA. We measured muscle protein turnover based on tracer-to-tracee ratios of the stable isotopes of leucine, phenylalanine, and ketoisocaproate (KIC) in artery and vein and muscle amino acyl-tRNA and muscle tissue fluid (TF) in 26 healthy subjects. A three-compartment model calculation based on arteriovenous and tRNA measurements was first performed and its domain of validity assessed. The results were then compared with those using simpler approaches based on surrogate measures of tRNA such as those of TF and KIC and a one-compartment model based on arteriovenous amino acids. In 96% of cases, the model using tRNA was applicable, but only in a lower percentage of cases were the results using surrogate measures applicable. Protein breakdown, protein synthesis, and shunting of amino acids from artery to vein were consistently underestimated, and fluxes of amino acid from artery to intracellular compartment and from intracellular compartment to vein were overestimated, when surrogate measures were used. The one-compartment model also underestimated protein breakdown and synthesis. Measurements using tissue fluid gave results closer to those based on tRNA. In conclusion, a three-compartment model using arteriovenous samples and amino acyl-tRNA provides measurements of muscle protein turnover of acceptable precision in 96% of cases. The precision was unacceptable in a substantial percentage of cases, and the accuracy of the estimation of protein fluxes was significantly affected when surrogate measures were used.

Glutamine kinetics and protein turnover in end-stage renal disease

2005 ◽  
Vol 288 (1) ◽  
pp. E37-E46 ◽  
Author(s):  
Dominic S. C. Raj ◽  
Tomas Welbourne ◽  
Elizabeth A. Dominic ◽  
Debra Waters ◽  
Robert Wolfe ◽  
...  
Keyword(s):  
Amino Acid ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Whole Body ◽  
Protein Breakdown ◽  
Protein Catabolism ◽  
Body Protein ◽  
Muscle Protein Breakdown ◽  
Stage Renal Disease ◽  
End Stage

Alanine and glutamine constitute the two most important nitrogen carriers released from the muscle. We studied the intracellular amino acid transport kinetics and protein turnover in nine end-stage renal disease (ESRD) patients and eight controls by use of stable isotopes of phenylalanine, alanine, and glutamine. The amino acid transport kinetics and protein turnover were calculated with a three-pool model from the amino acid concentrations and enrichment in the artery, vein, and muscle compartments. Muscle protein breakdown was more than synthesis (nmol·min−1·100 ml leg−1) during hemodialysis (HD) (169.8 ± 20.0 vs. 125.9 ± 21.8, P < 0.05) and in controls (126.9 ± 6.9 vs. 98.4 ± 7.5, P < 0.05), but synthesis and catabolism were comparable pre-HD (100.7 ± 15.7 vs. 103.4 ± 14.8). Whole body protein catabolism decreased by 15% during HD. The intracellular appearance of alanine (399.0 ± 47.1 vs. 243.0 ± 34.689) and glutamine (369.7 ± 40.6 vs. 235.6 ± 27.5) from muscle protein breakdown increased during dialysis (nmol·min−1·100 ml leg−1, P < 0.01). However, the de novo synthesis of alanine (3,468.9 ± 572.2 vs. 3,140.5 ± 467.7) and glutamine (1,751.4 ± 82.6 vs. 1,782.2 ± 86.4) did not change significantly intradialysis (nmol·min−1·100 ml leg−1). Branched-chain amino acid catabolism (191.8 ± 63.4 vs. −59.1 ± 42.9) and nonprotein glutamate disposal (347.0 ± 46.3 vs. 222.3 ± 43.6) increased intradialysis compared with pre-HD (nmol·min−1·100 ml leg−1, P < 0.01). The mRNA levels of glutamine synthase (1.45 ± 0.14 vs. 0.33 ± 0.08, P < 0.001) and branched-chain keto acid dehydrogenase-E2 (3.86 ± 0.48 vs. 2.14 ± 0.27, P < 0.05) in the muscle increased during HD. Thus intracellular concentrations of alanine and glutamine are maintained during HD by augmented release of the amino acids from muscle protein catabolism. Although muscle protein breakdown increased intradialysis, the whole body protein catabolism decreased, suggesting central utilization of amino acids released from skeletal muscle.

Skeletal and cardiac muscle protein turnover during cold acclimation in young rats

2000 ◽  
Vol 278 (3) ◽  
pp. R705-R711 ◽  
Author(s):  
T. A. McAllister ◽  
J. R. Thompson ◽  
S. E. Samuels
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Cardiac Muscle ◽  
Cold Acclimation ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Muscle Protein Turnover ◽  
Protein Mass ◽  
The Absolute

The effect of long-term cold exposure on skeletal and cardiac muscle protein turnover was investigated in young growing animals. Two groups of 36 male 28-day-old rats were maintained at either 5°C (cold) or 25°C (control). Rates of protein synthesis and degradation were measured in vivo on days 5, 10, 15, and 20. Protein mass by day 20 was ∼28% lower in skeletal muscle (gastrocnemius and soleus) and ∼24% higher in heart in cold compared with control rats ( P < 0.05). In skeletal muscle, the fractional rates of protein synthesis ( k syn) and degradation ( k deg) were not significantly different between cold and control rats, although k syn was lower (approximately −26%) in cold rats on day 5; consequent to the lower protein mass, the absolute rates of protein synthesis (approximately −21%; P < 0.05) and degradation (approximately −13%; P < 0.1) were lower in cold compared with control rats. In heart, overall, k syn(approximately +12%; P < 0.1) and k deg(approximately +22%; P < 0.05) were higher in cold compared with control rats; consequently, the absolute rates of synthesis (approximately +44%) and degradation (approximately +54%) were higher in cold compared with control rats ( P < 0.05). Plasma triiodothyronine concentration was higher ( P < 0.05) in cold compared with control rats. These data indicate that long-term cold acclimation in skeletal muscle is associated with the establishment of a new homeostasis in protein turnover with decreased protein mass and normal fractional rates of protein turnover. In heart, unlike skeletal muscle, rates of protein turnover did not appear to immediately return to normal as increased rates of protein turnover were observed beyond day 5. These data also indicate that increased rates of protein turnover in skeletal muscle are unlikely to contribute to increased metabolic heat production during cold acclimation.

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