Nutritional and endocrinological manipulation of lean deposition in forage-fed steers

The effect of supplementing grass silage with fishmeal on growth, muscle composition and the rate of muscle protein synthesis was investigated in young Friesian steers with and without oestradiol implants. The effect of the β-adrenergic agonist cimaterol was simultaneously investigated in animals fed on silage alone. Treatments lasted for 9 or 10 weeks. Fishmeal supplementation significantly increased animal growth rates (P < 0.001) and the weights of three dissected muscles (P < 0.001) compared with the silage-fed controls. These effects were further enhanced in animals also implanted with oestradiol. Muscle weights expressed as a proportion of body-weight were increased by fishmeal, suggesting that protein deposition had been enhanced. No further increase in the proportional muscle weights was obtained with oestradiol. Muscle dry matter content tended to be increased in both implanted and non-implanted animals receiving fishmeal compared with controls, but the proportions of protein, fat and ash were relatively constant. The intramuscular lipid composition was slightly altered by fishmeal. Muscle protein fractional synthetic rates (FSR), measured by continuous infusion of [3H]tyrosine, were increased by fishmeal in all three muscles of both implanted and non-implanted animals. There were no differences, however, due to oestradiol, over non-implanted fishmeal animals. This suggests that oestradiol may increase muscle accretion by reducing protein degradation rate. Cimaterol significantly increased longissimus dorsi (P < 0.05) and vastus lateralis (P < 0.01) muscle weights but had no effect on semitendinosus muscle weight or live-weight gain. The proportion of protein was increased (P <0.001) and the fat content reduced (P < 0.05) in all three muscles but intramuscular lipid composition was not markedly affected. Whilst methylhistidine: creatinine excretion was reduced by cimaterol, FSR were increased in the I. dorsi and v. lateralis muscles suggesting β-agonists have effects on both protein synthesis and protein degradation.

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Activation of mTORC1 signaling and protein synthesis in human muscle following blood flow restriction exercise is inhibited by rapamycin

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00600.2013 ◽

2014 ◽

Vol 306 (10) ◽

pp. E1198-E1204 ◽

Cited By ~ 52

Author(s):

David M. Gundermann ◽

Dillon K. Walker ◽

Paul T. Reidy ◽

Michael S. Borack ◽

Jared M. Dickinson ◽

...

Keyword(s):

Blood Flow ◽

Protein Synthesis ◽

Time Course ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Vastus Lateralis ◽

Human Muscle ◽

Leg Extension ◽

Or Groups ◽

Mtorc1 Signaling

Restriction of blood flow to a contracting muscle during low-intensity resistance exercise (BFR exercise) stimulates mTORC1 signaling and protein synthesis in human muscle within 3 h postexercise. However, there is a lack of mechanistic data to provide a direct link between mTORC1 activation and protein synthesis in human skeletal muscle following BFR exercise. Therefore, the primary purpose of this study was to determine whether mTORC1 signaling is necessary for stimulating muscle protein synthesis after BFR exercise. A secondary aim was to describe the 24-h time course response in muscle protein synthesis and breakdown following BFR exercise. Sixteen healthy young men were randomized to one of two groups. Both the control (CON) and rapamycin (RAP) groups completed BFR exercise; however, RAP was administered 16 mg of the mTOR inhibitor rapamycin 1 h prior to BFR exercise. BFR exercise consisted of four sets of leg extension exercise at 20% of 1 RM. Muscle biopsies were collected from the vastus lateralis before exercise and at 3, 6, and 24 h after BFR exercise. Mixed-muscle protein fractional synthetic rate increased by 42% at 3 h postexercise and 69% at 24 h postexercise in CON, whereas this increase was inhibited in the RAP group. Phosphorylation of mTOR (Ser2448) and S6K1 (Thr389) was also increased in CON but inhibited in RAP. Mixed-muscle protein breakdown was not significantly different across time or groups. We conclude that activation of mTORC1 signaling and protein synthesis in human muscle following BFR exercise is inhibited in the presence of rapamycin.

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Comparison of protein synthesis and degradation in incubated and perfused muscle

Biochemical Journal ◽

10.1042/bj2120649 ◽

1983 ◽

Vol 212 (3) ◽

pp. 649-653 ◽

Cited By ~ 35

Author(s):

A S Clark ◽

W E Mitch

Keyword(s):

Protein Synthesis ◽

Protein Degradation ◽

Insulin Treatment ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Muscle Protein Degradation ◽

Protein Synthesis And Degradation ◽

Synthesis And Degradation

Rates of muscle protein synthesis and degradation measured in the perfused hindquarter were compared with those in incubated epitrochlearis muscles. With fed or starved mature rats, results without insulin treatment were identical. With insulin treatment, protein synthesis in perfused hindquarters was greater, though protein degradation was the same. Thus rates of muscle protein degradation estimated by these two methods in vitro correspond closely.

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Resistance exercise acutely increases MHC and mixed muscle protein synthesis rates in 78–84 and 23–32 yr olds

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.2000.278.4.e620 ◽

2000 ◽

Vol 278 (4) ◽

pp. E620-E626 ◽

Cited By ~ 171

Author(s):

Debbie L. Hasten ◽

Jina Pak-Loduca ◽

Kathleen A. Obert ◽

Kevin E. Yarasheski

Keyword(s):

Protein Synthesis ◽

Resistance Exercise ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Vastus Lateralis ◽

Weight Lifting ◽

Synthesis Rate ◽

Vastus Lateralis Muscle ◽

Short Term ◽

Mixed Protein

We determined whether short-term weight-lifting exercise increases the synthesis rate of the major contractile proteins, myosin heavy chain (MHC), actin, and mixed muscle proteins in nonfrail elders and younger women and men. Fractional synthesis rates of mixed, MHC, and actin proteins were determined in seven healthy sedentary 23- to 32-yr-old and seven healthy 78- to 84-yr-old participants in paired studies done before and at the end of a 2-wk weight-lifting program. The in vivo rate of incorporation of 1-[13C]leucine into vastus lateralis MHC, actin, and mixed proteins was determined using a 14-h constant intravenous infusion of 1-[13C]leucine. Before exercise, the mixed and MHC fractional synthetic rates were lower in the older than in the younger participants ( P ≤ 0.04). Baseline actin protein synthesis rates were similar in the two groups ( P = not significant). Over a 2-wk period, participants completed ten 1- to 1.5-h weight-lifting exercise sessions: 2–3 sets per day of 9 exercises, 8–12 repetitions per set, at 60–90% of maximum voluntary muscle strength. At the end of exercise, MHC and mixed protein synthetic rates increased in the younger (88 and 121%) and older participants (105 and 182%; P < 0.001 vs. baseline). These findings indicate that MHC and mixed protein synthesis rates are reduced more than actin in advanced age. Similar to that of 23–32 yr olds, the vastus lateralis muscle in 78–84 yr olds retains the capacity to increase MHC and mixed protein synthesis rates in response to short-term resistance exercise.

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Resistance exercise load does not determine training-mediated hypertrophic gains in young men

Journal of Applied Physiology ◽

10.1152/japplphysiol.00307.2012 ◽

2012 ◽

Vol 113 (1) ◽

pp. 71-77 ◽

Cited By ~ 319

Author(s):

Cameron J. Mitchell ◽

Tyler A. Churchward-Venne ◽

Daniel W. D. West ◽

Nicholas A. Burd ◽

Leigh Breen ◽

...

Keyword(s):

Protein Synthesis ◽

Resistance Exercise ◽

Acute Exercise ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Vastus Lateralis ◽

Muscle Volume ◽

Maximal Strength ◽

Heavy Load ◽

Exercise Load

We have reported that the acute postexercise increases in muscle protein synthesis rates, with differing nutritional support, are predictive of longer-term training-induced muscle hypertrophy. Here, we aimed to test whether the same was true with acute exercise-mediated changes in muscle protein synthesis. Eighteen men (21 ± 1 yr, 22.6 ± 2.1 kg/m2; means ± SE) had their legs randomly assigned to two of three training conditions that differed in contraction intensity [% of maximal strength (1 repetition maximum)] or contraction volume (1 or 3 sets of repetitions): 30%-3, 80%-1, and 80%-3. Subjects trained each leg with their assigned regime for a period of 10 wk, 3 times/wk. We made pre- and posttraining measures of strength, muscle volume by magnetic resonance (MR) scans, as well as pre- and posttraining biopsies of the vastus lateralis, and a single postexercise (1 h) biopsy following the first bout of exercise, to measure signaling proteins. Training-induced increases in MR-measured muscle volume were significant ( P < 0.01), with no difference between groups: 30%-3 = 6.8 ± 1.8%, 80%-1 = 3.2 ± 0.8%, and 80%-3= 7.2 ± 1.9%, P = 0.18. Isotonic maximal strength gains were not different between 80%-1 and 80%-3, but were greater than 30%-3 ( P = 0.04), whereas training-induced isometric strength gains were significant but not different between conditions ( P = 0.92). Biopsies taken 1 h following the initial resistance exercise bout showed increased phosphorylation ( P < 0.05) of p70S6K only in the 80%-1 and 80%-3 conditions. There was no correlation between phosphorylation of any signaling protein and hypertrophy. In accordance with our previous acute measurements of muscle protein synthetic rates a lower load lifted to failure resulted in similar hypertrophy as a heavy load lifted to failure.

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Effect of an Amino Acid, Protein, and Carbohydrate Mixture on Net Muscle Protein Balance after Resistance Exercise

International Journal of Sport Nutrition and Exercise Metabolism ◽

10.1123/ijsnem.14.3.255 ◽

2004 ◽

Vol 14 (3) ◽

pp. 255-271 ◽

Cited By ~ 69

Author(s):

Elisabet Børsheim ◽

Asle Aarsland ◽

Robert R. Wolfe

Keyword(s):

Protein Synthesis ◽

Resistance Exercise ◽

Whey Protein ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Vastus Lateralis ◽

Area Under The Curve ◽

Constant Infusion ◽

Delayed Response ◽

Protein Balance

This study tests the hypotheses that (a) a mixture of whey protein, amino acids (AA), and carbohydrates (CHO) stimulates net muscle protein synthesis to a greater extent than isoenergetic CHO alone after resistance exercise; and (b) that the stimulatory effect of a protein, AA, and CHO mixture will last beyond the 1 st hour after intake. Eight subjects participated in 2 trials. In one (PAAC), they ingested 77.4 g CHO, 17.5 g whey protein, and 4.9 g AA 1 hr after resistance exercise. In the other (CON), 100 g CHO was ingested instead. They received a primed constant infusion of L-[2H5]-phenylalanine, and samples from femoral artery and vein, and biopsies from vastus lateralis were obtained. The area under the curve for net uptake of phenylalanine into muscle above pre-drink value was 128 ±42 mg • leg-1 (PAAC) versus 32 ± 10 mg - leg-1 (CON) for the 3 hr after the drink (p = .04). The net protein balance response to the mixture consisted of two components, one rapid immediate response, and a smaller delayed response about 90 min after drink, whereas in CON only a small delayed response was seen. We conclude that after resistance exercise, a mixture of whey protein, AA, and CHO stimulated muscle protein synthesis to a greater extent than isoenergetic CHO alone. Further, compared to previously reported findings, the addition of protein to an AA + CHO mixture seems to extend the anabolic effect.

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Does habitual dietary intake influence myofiber hypertrophy in response to resistance training? A cluster analysis

Applied Physiology Nutrition and Metabolism ◽

10.1139/h09-038 ◽

2009 ◽

Vol 34 (4) ◽

pp. 632-639 ◽

Cited By ~ 21

Author(s):

Anna E. Thalacker-Mercer ◽

John K. Petrella ◽

Marcas M. Bamman

Keyword(s):

Cluster Analysis ◽

Protein Synthesis ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Vastus Lateralis ◽

Muscle Growth ◽

Daily Intake ◽

Dietary Recommendations ◽

Extrinsic Factors ◽

Cross Sectional

Although resistance exercise training (RT) is a common intervention to stimulate muscle protein synthesis and increase skeletal muscle mass, the optimal daily protein and total energy intakes sufficient to support RT-mediated muscle growth are as yet unclear. Further, the efficacy of RT varies widely among adults of all ages and whether this is attributable to interindividual differences in nutrition is not known. To determine if self-selected daily intake of macronutrients and specific components of dietary protein and fat are predictive of the magnitude of RT-mediated muscle growth, detailed 4-day dietary records were analyzed on 60 subjects previously clustered (K-means cluster analysis) as non-, modest, and extreme responders (non, n = 16; mod, n = 29; xtr, n = 15), based on the magnitudes of change in vastus lateralis myofiber cross-sectional area following a 16-week, 3-day-per-week, high-intensity RT. Despite the marked contrast between 60% myofiber hypertrophy in xtr and zero growth in non, we found no differences among response clusters in daily intakes of energy (mean ± SEM: non 102 ± 8; mod 111 ± 6; xtr 109 ± 5 kJ·kg–1·day–1), protein (non 0.97 ± 0.08; mod 1.07 ± 0.07; xtr 1.05 ± 0.06 g·kg–1·day–1), carbohydrate (non 3.02 ± 0.24; mod 3.18 ± 0.20; xtr 3.14 ± 0.17 g·kg–1·day–1), and fat (non 0.95 ± 0.09; mod 1.05 ± 0.08; xtr 1.03 ± 0.08 g·kg–1·day–1), which generally met or exceeded dietary recommendations. There were no cluster differences in intakes of branched chain amino acids known to stimulate muscle protein synthesis. Using the novel K-means clustering approach, we conclude from this preliminary study that protein and energy intakes were sufficient to facilitate modest and extreme muscle growth during RT and intrinsic or extrinsic factors other than nutrient ingestion apparently impaired the anabolic response in nonresponders.

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Artificial gravity maintains skeletal muscle protein synthesis during 21 days of simulated microgravity

Journal of Applied Physiology ◽

10.1152/japplphysiol.91137.2008 ◽

2009 ◽

Vol 107 (1) ◽

pp. 34-38 ◽

Cited By ~ 60

Author(s):

T. B. Symons ◽

M. Sheffield-Moore ◽

D. L. Chinkes ◽

A. A. Ferrando ◽

D. Paddon-Jones

Keyword(s):

Skeletal Muscle ◽

Protein Synthesis ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Vastus Lateralis ◽

Bed Rest ◽

Artificial Gravity ◽

Skeletal Muscle Protein ◽

Longitudinal Loading ◽

Breakdown Rates

We sought to determine the effects of longitudinal loading (artificial gravity) on skeletal muscle protein kinetics in 15 healthy young males after 21 days of 6° head-down tilt bed rest [experimental treatment (Exp) group: n = 8, 31 ± 1 yr; control (Con) group; n = 7, 28 ± 1 yr, means ± SE]. On days 1 and 21 of bed rest, postabsorptive venous blood samples and muscle biopsies (vastus lateralis and soleus) were obtained during a 1-h pulse bolus infusion protocol (0 min, l-[ ring-13C6]phenylalanine, 35 μmol/kg; 30 min, l-[ ring-15N]phenylalanine, 35 μmol/kg). Outcome measures included mixed muscle fractional synthesis (FSR) and breakdown rates (FBR). The Exp group experienced 1 h of longitudinal loading (2.5G at the feet) via a short-radius centrifuge during each day of bed rest. Mixed muscle FSR in the Con group was reduced by 48.5% ( day 1, 0.081 ± 0.000%/h vs. day 21, 0.042 ± 0.000%/h; P = 0.001) in vastus lateralis after 21 days of bed rest, whereas the Exp group maintained their rate of protein synthesis. A similar but nonsignificant change in FSR was noted for the soleus muscle (Exp, −7%; Con, −22%). No changes in muscle protein breakdown were observed. In conclusion, 1 h of daily exposure to artificial gravity maintained the rate of protein synthesis of the vastus lateralis and may represent an effective adjunct countermeasure to combat the loss of muscle mass and functional during extended spaceflight.

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A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00488.2005 ◽

2006 ◽

Vol 291 (2) ◽

pp. E381-E387 ◽

Cited By ~ 505

Author(s):

Christos S. Katsanos ◽

Hisamine Kobayashi ◽

Melinda Sheffield-Moore ◽

Asle Aarsland ◽

Robert R. Wolfe

Keyword(s):

Protein Synthesis ◽

Amino Acid ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Vastus Lateralis ◽

The Elderly ◽

Essential Amino Acids ◽

Vastus Lateralis Muscle ◽

Young Subjects ◽

Stimulation Of

This study was designed to evaluate the effects of enriching an essential amino acid (EAA) mixture with leucine on muscle protein metabolism in elderly and young individuals. Four (2 elderly and 2 young) groups were studied before and after ingestion of 6.7 g of EAAs. EAAs were based on the composition of whey protein [26% leucine (26% Leu)] or were enriched in leucine [41% leucine (41% Leu)]. A primed, continuous infusion of l-[ ring-2H5]phenylalanine was used together with vastus lateralis muscle biopsies and leg arteriovenous blood samples for the determinations of fractional synthetic rate (FSR) and balance of muscle protein. FSR increased following amino acid ingestion in both the 26% (basal: 0.048 ± 0.005%/h; post-EAA: 0.063 ± 0.007%/h) and the 41% (basal: 0.036 ± 0.004%/h; post-EAA: 0.051 ± 0.007%/h) Leu young groups ( P < 0.05). In contrast, in the elderly, FSR did not increase following ingestion of 26% Leu EAA (basal: 0.044 ± 0.003%/h; post-EAA: 0.049 ± 0.006%/h; P > 0.05) but did increase following ingestion of 41% Leu EAA (basal: 0.038 ± 0.007%/h; post-EAA: 0.056 ± 0.008%/h; P < 0.05). Similar to the FSR responses, the mean response of muscle phenylalanine net balance, a reflection of muscle protein balance, was improved ( P < 0.05) in all groups, with the exception of the 26% Leu elderly group. We conclude that increasing the proportion of leucine in a mixture of EAA can reverse an attenuated response of muscle protein synthesis in elderly but does not result in further stimulation of muscle protein synthesis in young subjects.

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Effects of Fortetropin on the Rate of Muscle Protein Synthesis in Older Men and Women: A Randomized, Double-Blinded, Placebo-Controlled Study

The Journals of Gerontology Series A ◽

10.1093/gerona/glaa162 ◽

2020 ◽

Vol 76 (1) ◽

pp. 108-114

Author(s):

William Evans ◽

Mahalakshmi Shankaran ◽

Edna Nyangau ◽

Tyler Field ◽

Hussein Mohammed ◽

...

Keyword(s):

Protein Synthesis ◽

Muscle Mass ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Vastus Lateralis ◽

Egg Yolk ◽

Older Men ◽

Controlled Study ◽

Lipid Complex ◽

Gene Ontologies

Abstract Background Fortetropin is a proteo-lipid complex made from fertilized egg yolk and, in young men, has been shown to increase lean body mass. Methods The purpose of this study was to examine the effects of 21 days of Fortetropin supplementation on the fractional synthetic rate (FSR) of muscle protein in 10 healthy, older men and 10 women (66.4 ± 4.5 y). We used 2H2O labeling to measure FSR of multiple muscle protein ontologies. D3-creatine dilution was used to determine muscle mass at baseline. Subjects ingested 70% 2H2O for 21 day and saliva samples were collected to determine body 2H2O enrichment. A microbiopsy was obtained from the m. vastus lateralis on Day 21. Subjects were randomly assigned to Fortetropin (19.8 g/d) or placebo (cheese powder, 19.8 g/d). Results Restricting kinetic data to proteins with ≥2 peptides measured in at least 4 subjects per group resulted in 117 proteins meeting these criteria. The mean FSR for a majority of proteins in several muscle gene ontologies was higher in the Fortetropin group compared to placebo (32/38 myofibril proteins, 33/44 sarcoplasmic proteins, and 12/17 mitochondrial proteins) and this proportion was significantly different between groups using a binomial test and were independent of sex or baseline muscle mass. Conclusions The overall magnitude of the difference in muscle protein FSR of Fortetropin from placebo was 18%, with multiple gene ontologies affected. While these results should be confirmed in larger cohorts, they suggest that Fortetropin supplementation is effective for promoting muscle protein synthesis in older people.

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