scholarly journals Altered protein kinetics in vivo after single-limb burn injury

1984 ◽  
Vol 223 (3) ◽  
pp. 747-753 ◽  
Author(s):  
R E Shangraw ◽  
J Turinsky
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Turnover ◽  
Burn Injury ◽  
Whole Body ◽  
Liver Protein ◽  
Protein Kinetics ◽  
Tissue Protein ◽  
Systemic Factors ◽  
Control Protein

Recovery from burn injury is associated with stimulated whole-body protein turnover. Since skeletal muscle and liver are the tissues most likely to influence whole-body measurements, we studied protein kinetics in soleus and plantaris muscles as well as liver 3 days after a 3 s burn on one hindlimb of the rat. Muscles from both the burned and unburned limbs of burned rats were compared with those of uninjured controls to distinguish between local and systemic factors involved. The following measurements were performed: (1) fractional growth rate of the tissue protein pool, determined from tissue protein content on days 2, 3 and 4; (2) fractional protein-synthetic rate, measured by [14C]tyrosine constant infusion on day 3; (3) fractional protein-degradation rate, calculated from the difference between the rates of protein synthesis and growth. Protein growth by soleus and plantaris muscles of control rats and unburned limb of burned rats was not paralleled by those in the burned limb, which showed progressive atrophy between 2 and 4 days post-burn (P less than 0.005). Protein synthesis by soleus but not plantaris muscle in the unburned limb of burned rats was enhanced by 62% (P less than 0.04) above control. Protein synthesis by burned-limb soleus and plantaris muscles was elevated by 114% (P less than 0.001) and 67% (P less than 0.02) respectively above control. Protein degradation by both soleus and plantaris muscles in the unburned limb of burned rats did not differ from control. In contrast, that of soleus and plantaris muscles in the burned limb was stimulated by 230% (P less than 0.001) and 164% (P less than 0.001) respectively compared with controls. Protein turnover of soleus muscles in both control and burned rats was more rapid than in corresponding plantaris muscles. Liver protein mass exhibited steady growth in control rats, but remained unchanged in burned animals between 2 and 4 days post-burn. Liver protein synthesis in burned rats was elevated by 56% (P less than 0.01) and protein breakdown was stimulated by 61% (P less than 0.002) above those of controls. The data indicate that both local and systemic factors influence tissue protein turnover in animals recovering from a single-hindlimb scald.

scholarly journals Exercise-related changes in protein turnover in mammalian striated muscle

1991 ◽  
Vol 160 (1) ◽  
pp. 127-148 ◽  
Author(s):  
D. F. Goldspink
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Turnover ◽  
Striated Muscle ◽  
Contractile Activity ◽  
Whole Body ◽  
Phenotypic Properties ◽  
Type Of Exercise ◽  
Passive Stretch

Contractile activity is an important determinant of the size, rate of protein turnover and phenotypic properties of muscle. Animal models that decrease muscle activity invariably accelerate the rate of protein degradation, usually complementing decreases in the rate of protein synthesis. The net effect is muscle atrophy. By contrast, increased activity and/or passive stretch enhance the synthesis of new proteins, whilst protein catabolism may be either decreased or increased. Muscle hypertrophy results. Endurance activities in man and animals usually induce cardiac hypertrophy, and increased fatigue resistance in skeletal muscle. During exercise the whole body and its skeletal musculature exhibit a negative nitrogen balance, and there is general agreement that rates of protein synthesis are decreased. Changes in protein degradation are, however, much less clearly defined. Resistance exercises induce the opposite changes, with the size of the heart remaining unchanged whilst the bulk and strength of skeletal muscle increase. No real consensus currently exists about the nature of the changes in protein turnover with this type of exercise. More carefully designed and executed experiments are required.

scholarly journals Dietary lysine deficiency greatly affects muscle and liver protein turnover in growing chickens

1996 ◽  
Vol 75 (6) ◽  
pp. 853-865 ◽  
Author(s):  
S. Tesseraud ◽  
R. Peresson ◽  
J. Lopes ◽  
A.M. Chagneau
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Pectoralis Major Muscle ◽  
Pectoralis Major ◽  
Translational Efficiency ◽  
Liver Protein ◽  
Deficient Diet ◽  
Principal Mechanism ◽  
Tissue Protein

We analysed the respective influences of age and lysine deficiency on skeletal muscle and liver protein turnover. Growing male broilers were fed ad libirum on isoenergetic diets containing 2OO g crude protein/kg which varied in their lysine content (7·7 or 10·1 g/kg). Fractional rates of protein synthesis (FSR) were measured in vivo in the liver and the pectoralis major muscle of 2-, 3- and 4-week-old chickens (flooding dose of l-[143H]phenylalanine). Fractional rates of proteolysis (FBR) were estimated for the same tissues as the difference between synthesis and growth. Over the 2-week period liver FSR and FBR were unchanged, whereas muscle FSR decreased with age. This developmental decline was related to the lower capacity for protein synthesis (Cs) without any modifications of the translational efficiency. Whatever the age, lysine deficiency resulted in significant decreases in body weight, tissue protein content and tissue protein deposition, apparently because of reduced amounts of proteins synthesized. We recorded a difference in the response of the two tissues to lysine deficiency, the pectoralis major being more sensitive than the liver. When comparing birds of the same age, liver FSR and FBR were not modified by the diet, where as muscle FSR, Cs and FBR were higher in chicks fed on a lysinc-deficient diet than in the controls. Conversely, when chicks of similar weights were compared, the main effect of the dietary deficiency was an increase in muscle FBR. The results suggest that lysine deficiency not only delayed chick development so that protein turnover was affected, but also induced greater changes in metabolism. Thus, the principal mechanism whereby muscle mass decreased appeared to be a change in FBR.

scholarly journals Casein and soya-bean protein have different effects on whole body protein turnover at the same nitrogen balance

1994 ◽  
Vol 72 (1) ◽  
pp. 69-81 ◽  
Author(s):  
K. Nielsen ◽  
J. Kondrup ◽  
P. Elsner ◽  
A. Juul ◽  
E. S. Jensen
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Degradation ◽  
Protein Turnover ◽  
Soya Bean ◽  
Whole Body ◽  
Body Protein ◽  
Protein Free Diet ◽  
Hydrolysed Casein ◽  
Bean Protein

The present study examined whether different proteins have different effects on whole-body protein turnover in adult rats. The rats were either starved, given a protein-free but energy-sufficient diet (1 MJ/kg body weight (BW) per d) or a diet containing intact casein, hydrolysed casein, or hydrolysed soya-bean protein at a level of 9.1 g/kg BW per d. The diets, which were isoenergetic with the same carbohydrate: fat ratio, were given as a continuous intragastric infusion for at least 4 d. During the last 19 h 15N-glycine (a primed continuous infusion) was given intragastrically and 15N was recovered from urinary ammonia and urea during isotope steady state for measurement of protein synthesis and protein degradation. Compared with starvation the protein-free diet decreased N excretion by 75%, probably by increasing the rate of reutilization of amino acids from endogenous proteins for protein synthesis. The protein diets produced a positive N balance which was independent of the protein source. Intact and hydrolysed casein increased protein synthesis 2.6- and 2.0-fold respectively, compared with the protein- free diet. Protein degradation increased 1.4- and 1.2-fold respectively. Hydrolysed soya-bean protein did not increase protein synthesis but decreased protein degradation by 35% compared with the protein-free diet. Compared with the hydrolysed soya-bean protein, intact casein resulted in 2.2- and 2.8-fold higher rates of protein synthesis and degradation respectively. These results are not easily explained by known sources of misinterpretation associated with the 15N-glycine method. Hydrolysed casein and hydrolysed soya-bean protein produced similar concentrations of insulin-like growth factor-1, insulin, glucagon, and corticosterone. The difference in amino acid composition between the dietary proteins was reflected in plasma amino acid composition and this is suggested to be responsible for the different effect on protein turnover. Preliminary results from this study have previously been published in abstract form (Nielsen et al. 1991).

scholarly journals A Whole-Grain Diet Improves Whole-Body Protein Turnover Compared to a Macronutrient-Matched Refined-Grain Diet in Adults with Overweight/Obesity

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 1661-1661
Author(s):  
Jacob Mey ◽  
John Kirwan
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Protein Turnover ◽  
Whole Grains ◽  
Whole Body ◽  
Protein Breakdown ◽  
Whole Grain ◽  
Protein Kinetics ◽  
Body Protein ◽  
Fasted State

Abstract Objectives We investigated the effect of consuming a whole-grain diet on whole-body protein metabolism compared to a macronutrient-matched refined-grain diet in adults with overweight/obesity using labelled amino acids (ClinicalTrials.gov Identifier: NCT01411540). Methods We conducted a randomized, controlled crossover trial in 14 adults with overweight/obesity (age: 40 ± 7 yrs, BMI: 33 ± 5 kg/m2) in which isocaloric, macronutrient-matched whole-grain (WG) and refined-grain (RG) diets were fully provided for two 8-week periods (with a 10-week washout period). Diets differed only in the inclusion of whole grains (50 g/1000 kcal). Body composition was measured via DEXA. Whole-body protein kinetics were assessed before and after each diet in the fasted state (13C-Leucine, primed, constant infusion) and over 24 hours (15N-Glycine, bolus). Protein kinetics were normalized to fat-free mass (FFM). Results Both diets resulted in mild weight loss (WG: −2.0 ± 2.5 kg; RG: −2.9 ± 3.3 kg; both P = 0.01 compared to baseline). Fasted-state leucine kinetics revealed greater protein synthesis (WG: 205 ± 61 µmol/kgFFM/hr; RG: 178 ± 36 µmol/kgFFM/hr; P = 0.04) and protein breakdown (WG: 235 ± 68 µmol/kgFFM/hr; RG: 203 ± 40 µmol/kgFFM/hr, P = 0.03) on a WG vs RG diet. This resulted in a more negative fasted-state net balance on a WG diet (WG: −30 ± 8 µmol/kg/hr; RG: −25 ± 6 µmol/kg/hr, P = 0.02). In contrast, 24-hour whole-body protein turnover measured by the end-product method (15N-Glycine), revealed greater protein synthesis (WG: 316 ± 135 mg protein/kgFFM/hr; RG: 250 ± 94 mg protein/kgFFM/hr) with no difference in protein breakdown, yielding a more positive 24-hr net balance on a WG diet (WG: 31 ± 21 mg protein/kgFFM/hr; RG: 10 ± 34 mg protein/kgFFM/hr). Conclusions A whole-grain diet increases whole-body leucine flux and results in a greater 24-hr net protein balance in adults with overweight/obesity compared to a refined-grain diet. This trial suggests whole-grains have an independent effect on protein metabolism and may benefit adults with overweight/obesity. Funding Sources This research was supported by the NIH (UL1 RR024989, T32DK007319 (JPK); T32AT004094 (JTM – trainee)) and an investigator-initiated grant from Nestle (JPK). Nestle Product Technology Center and Cereal Partners Worldwide provided the study meals and foods.

Effects in vivo of decreased plasma and intracellular muscle glutamine concentration on whole-body and hindquarter protein kinetics in rats

1999 ◽  
Vol 96 (6) ◽  
pp. 639-646 ◽  
Author(s):  
Steven W. M. OLDE DAMINK ◽  
Ivo DE BLAAUW ◽  
Nicolaas E. P. DEUTZ ◽  
Peter B. SOETERS
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Whole Body ◽  
Glutamine Supplementation ◽  
Constant Infusion ◽  
Glutamine Concentration ◽  
Protein Kinetics ◽  
Body Protein

Glutamine is considered to be a ‘conditionally’ essential amino acid. During situations of severe stress like sepsis or after trauma there is a fall in plasma glutamine levels, enhanced glutamine turnover and intracellular muscle glutamine depletion. Under these conditions, decreased intramuscular glutamine concentration correlates with reduced rates of protein synthesis. It has therefore been hypothesized that intracellular muscle glutamine levels have a regulatory role in muscle protein turnover rates. Administration of the glutamine synthetase inhibitor methionine sulphoximine (MSO) was used to decrease glutamine levels in male Wistar rats. Immediately after the MSO treatment (t = 0 h), and at t = 6 h and t = 12 h, rats received intraperitoneal injections (10 ml/100 g body weight) with glutamine (200 mM) to test whether this attenuated the fall in plasma and intracellular muscle glutamine. Control animals received alanine and saline after MSO treatment, while saline was also given to a group of normal rats. At t = 18 h rats received a primed constant infusion of l-[2,6-3H]phenylalanine. A three-pool compartment tracer model was used to measure whole-body protein turnover and muscle protein kinetics. Administration of MSO resulted in a 40% decrease in plasma glutamine and a 60% decrease in intracellular muscle glutamine, both of which were successfully attenuated by glutamine infusions. The decreased intracellular muscle glutamine levels had no effect on whole-body protein turnover or muscle protein kinetics. Also, glutamine supplementation did not alter these parameters. Alanine supplementation increased both hindquarter protein synthesis and breakdown but the net balance of phenylalanine remained unchanged. In conclusion, our results show that decreased plasma and muscle glutamine levels have no effect on whole-body protein turnover or muscle protein kinetics. Therefore, it is unlikely that, in vivo, the intracellular muscle concentration of glutamine is a major regulating factor in muscle protein kinetics.

scholarly journals Action and interaction of growth hormone and the β-agonist, clenbuterol, on growth, body composition and protein turnover in dwarf mice

1991 ◽  
Vol 65 (2) ◽  
pp. 115-129 ◽  
Author(s):  
P. C. Bates ◽  
J. M. Pell
Keyword(s):  
Skeletal Muscle ◽  
Growth Hormone ◽  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Tail Length ◽  
Whole Body ◽  
Tissue Protein ◽  
Dwarf Mice

The responses of dwarf mice to dietary administration of clenbuterol (3 mg/kg diet), daily injections of growth hormone (15 μg/mouse per d) or both treatments combined were investigated and their actions, and any interactions, on whole-body growth, composition and protein metabolism, and muscle, liver and heart growth and protein metabolism, were studied at days 0, 4 and 8 of treatment. Growth hormone, with or without clenbuterol, induced an increase in body-weight growth and tail length growth; clenbuterol alone did not affect body-weight or tail length. Both growth hormone and clenbuterol reduced the percentage of whole-body fat and increased the protein:fat ratio. They also increased protein synthesis rates of whole body and muscle, although the magnitude of the increase was greater in response to growth hormone than to clenbuterol. Clenbuterol specifically induced growth of muscle, with a decrease in liver protein content, whereas growth hormone exhibited more general anabolic effects on tissue protein. Previous reports have suggested that effects of clenbuterol on skeletal muscle are mediated, at least in part, via decreased rates of protein degradation; we could find little evidence of any decrease in whole-body or tissue protein degradation and anabolic effects were largely due to increases in protein synthesis rates. However, small increases in muscle protein degradation rate were observed in response to growth hormone. Growth hormone induced a progressive increase in serum insulin-like growth factor-1 concentration, whereas there was no change with clenbuterol administration. Anabolic effects on whole-body and skeletal muscle protein metabolism, therefore, appear to be initially via independent mechanisms but are finally mediated by a common response (increased protein synthesis) in dwarf mice.

Ornithine alpha-ketoglutarate modulates tissue protein metabolism in burn-injured rats.

1997 ◽  
Vol 273 (3) ◽  
pp. E557 ◽  
Author(s):  
J Le Boucher ◽  
C Obled ◽  
M C Farges ◽  
L Cynober
Keyword(s):  
Protein Synthesis ◽  
Burn Injury ◽  
Tissue Level ◽  
Whole Body ◽  
Synthesis Rate ◽  
Total Protein Content ◽  
Tissue Protein ◽  
Male Wistar Rats ◽  
Ad Libitum

Enterally administered ornithine alpha-ketoglutarate (OKG) displays whole body anabolic and anticatabolic properties in trauma situations, especially after burn injury. The aim of this study was to get information about the anabolic effect of OKG at tissue level. Thirty-six male Wistar rats (95 +/- 7 g) were allocated to four groups. Eighteen rats were burned by water (20% body surface area). After a 24-h fast (day 0-day 1), rats were enterally refed for 48 h (day 1-day 3) by use of Osmolite as a low-calorie, low-nitrogen regimen supplemented with either 5 g OKG.kg-1.day-1 (B-OKG) or an equivalent amount of nitrogen in the form of glycine (B-Gly). Nonburned pair-fed controls treated with glycine (C-Gly) and healthy rats fed ad libitum were also studied. On day 3, protein synthesis rates (large dose method), free glutamine concentrations, and total protein content were assessed in tissues. Myofibrillar degradation was assessed by measuring urinary 3-methylhistidine excretion daily from day 0 to day 3. With regard to tissue protein synthesis rates, we demonstrate for the first time that OKG displays anabolic properties in the jejunum [fractional synthesis rate (FSR) in %/day, ad libitum = 101.9 +/- 4.0; C-Gly = 84.7 +/- 3.1, P < 0.01 vs. ad libitum; B-Gly = 84.5 +/- 1.6, P < 0.01 vs. ad libitum; B-OKG = 97.5 +/- 3.2, P < 0.05 vs. C-Gly and B-Gly] as well as in the liver (FSR in %/day, ad libitum = 75.9 +/- 3.7; C-Gly = 53.2 +/- 3.8, P < 0.01 vs. ad libitum; B-Gly = 70.2 +/- 2.0, P < 0.01 vs. C-Gly; B-OKG = 98.7 +/- 4.6, P < 0.01 vs. ad libitum, C-Gly and B-Gly), the latter having previously been observed in vitro. Furthermore, we confirm that OKG inhibits myofibrillar degradation, counteracts the trauma-induced fall of muscle glutamine pool, and induces an increase in glutamine concentration in the jejunum.

scholarly journals The effects of dietary methyl donors on methionine partitioning in the neonatal piglet

2015 ◽  
Vol 40 (11) ◽  
pp. 1218-1218 ◽  
Author(s):  
Jason Lorne Robinson
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Whole Body ◽  
Liver Protein ◽  
Dietary Intakes ◽  
Body Protein ◽  
Methyl Donors ◽  
Neonatal Piglets ◽  
Methionine Cycle ◽  
Critical Nutrients

The metabolism of the indispensable amino acid methionine is critical during development. Methionine is used to synthesize protein for growth and, using the methionine cycle, it is the precursor of >50 critical nutrients and contributes to epigenetic regulation. Therefore, the dietary methionine requirement must factor all the potential roles of methioine. Three major processes summarize the methionine cycle: transmethylation (TM), which transfers methyl groups to nutrient precursors and DNA; transsulfuration (TS), which represents methionine disposal; and remethylation (RM), which resynthesizes methionine using the dietary methyl donors folate and choline (via betaine). Dietary intakes of folate vary drastically, and choline intakes are often below the adequate intakes during pregnancy and in early life, which we hypothesized would influence the methionine requirement. To test our hypothesis, we fed 4- to 8-day-old neonatal piglets a low-methionine diet that was either deficient (MD−) or replete (MS+) in dietary methyl donors. We evaluated how methionine was balanced between the major TM reactions and protein synthesis. The MD− group exhibited marked differences in TM as creatine synthesis was ≈30% less (p < 0.05) and phosphatidylcholine synthesis was ≈60% more (p < 0.05) during MD− feeding. Interestingly, while MD− feeding did not affect liver protein synthesis, the methionine availability and protein synthesis were lower in skeletal muscle of the MD− versus MS+ animals (p < 0.05). Furthermore, whole-body protein turnover was also reduced during MD− feeding (p < 0.05), which is significant as protein turnover is especially critical during infancy. Next, we measured the effect of methyl donors on the rates of TM, TS, and RM. The rates of RM and TM were reduced by ≈75% in the MD− group (p < 0.05), while TS was unchanged. To evaluate the effectiveness of individual methyl donors on RM, we “rescued” a second group of MD− animals with betaine (MD + B), folate (MD + F) or both (MD + FB). The rate of RM and TM increased by ≈2-fold after rescue (p < 0.05) and reduced protein breakdown (p < 0.05). These studies showed that dietary methyl donors affect neonatal methionine metabolism, which should be considered when defining the dietary requirements of methionine during development.

scholarly journals Effect of long-term refeeding on protein metabolism in patients with cirrhosis of the liver

1997 ◽  
Vol 77 (2) ◽  
pp. 197-212 ◽  
Author(s):  
Jens Kondrup ◽  
Klaus Nielsen ◽  
Anders Juul
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Metabolism ◽  
Cirrhosis Of The Liver ◽  
N Balance ◽  
Whole Body ◽  
Protein Requirement ◽  
Protein Utilization ◽  
Igf I

Patients with cirrhosis of the liver require an increased amount of protein to achieve N balance. However, the utilization of protein with increased protein intake, i.e. the slope from regression analysis of N balance v. intake, is highly efficient (Nielsen et al. 1995). In the present study, protein requirement and protein utilization were investigated further by measuring protein synthesis and degradation. In two separate studies, five or six patients with cirrhosis of the liver were refed on a balanced diet for an average of 2 or 4 weeks. Protein and energy intakes were doubled in both studies. Initial and final whole-body protein metabolism was measured in the fed state by primed continous [15N]glycine infusion. Refeeding caused a statistically significant increase of about 30% in protein synthesis in both studies while protein degradation was only slightly affected. The increase in protein synthesis was associated with significant increases in plasma concentrations of total amino acids (25%), leucine (58%), isoleucine (82%), valine (72%), proline (48%) and triiodothyronine (27%) while insulin, growth hormone, insulin-like growth factor (IGF)-I and IGF-binding protein-3 were not changed significantly. The results indicate that the efficient protein utilization is due to increased protein synthesis, rather than decreased protein degradation, and suggest that increases in plasma amino acids may be responsible for the increased protein synthesis. A comparison of the patients who had a normal protein requirement with the patients who had an increased protein requirement suggests that the increased protein requirement is due to a primary increase in protein degradation. It is speculated that this is due to low levels of IGF-I secondary to impaired liver function, since initial plasma concentration of IGF-I was about 25% of control values and remained low during refeeding.

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