scholarly journals Amino Acid Concentrations and Protein Metabolism of Two Types of Rat Skeletal Muscle in Postprandial State and After Brief Starvation

2017 ◽  
pp. 959-967 ◽  
Author(s):  
M. HOLEČEK ◽  
S. MIČUDA
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Metabolism ◽  
Cathepsin B ◽  
Fed State ◽  
Postprandial State ◽  
Slow Twitch ◽  
Fast Twitch ◽  
Amino Acid Concentrations

We have investigated amino acid concentrations and protein metabolism in musculus extensor digitorum longus (EDL, fast-twitch, white muscle) and musculus soleus (SOL, slow-twitch, red muscle) of rats sacrificed in the fed state or after one day of starvation. Fractional protein synthesis rates (FRPS) were measured using the flooding dose method (L-[3,4,5-3H]phenylalanine). Activities of two major proteolytic systems in muscle (the ubiquitin-proteasome and lysosomal) were examined by measurement of chymotrypsin like activity of proteasome (CTLA), expression of ubiquitin ligases atrogin-1 and muscle-ring-finger-1 (MuRF-1), and cathepsin B and L activities. Intramuscular concentrations of the most of non-essential amino acids, FRPS, CTLA and cathepsin B and L activities were in postprandial state higher in SOL when compared with EDL. The differences in atrogin-1 and MuRF-1 expression were insignificant. Starvation decreased concentrations of a number of amino acids and increased concentrations of valine, leucine, and isoleucine in blood plasma. Starvation also decreased intramuscular concentrations of a number of amino acids differently in EDL and SOL, decreased protein synthesis (by 31 % in SOL and 47 % in EDL), and increased expression of atrogin-1 and MuRF-1 in EDL. The effect of starvation on CTLA and cathepsin B and L activities was insignificant. It is concluded that slow-twitch (red) muscles have higher rates of protein turnover and may adapt better to brief starvation when compared to fast-twitch (white) muscles. This phenomenon may play a role in more pronounced atrophy of white muscles in aging and muscle wasting disorders.

On the Role of Branched-Chain Amino Acids in Protein Turnover of Skeletal Muscle. Studies in vivo with L-Norleucine

1985 ◽  
Vol 40 (5-6) ◽  
pp. 427-437 ◽  
Author(s):  
Klaus-Joachim Schott ◽  
Jochen Gehrmann ◽  
Ulla Potter ◽  
Volker Neuhoff
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Small Intestine ◽  
Amino Acid ◽  
Protein Metabolism ◽  
Protein Turnover ◽  
Protein Concentration ◽  
Amino Acid Concentrations

Abstract 1. The effect of ʟ-norleucine, an isomer of leucine, on protein metabolism in vivo was studied in suckling rats. Rats were injected subcutaneously with various doses of ʟ-norleucine (0.5 and 5.0 μmol/g body wt.) every 12 h from 3 to 15 days post partum. Protein concentration, amino acid concentrations, and incorporation of [3H]tyrosine into protein were analyzed in liver, muscles of thigh and small intestine. Amino acid concentrations and insulin levels in serum were also measured. 2. At 5 days of age, norleucine induced an increase in protein concentration of skeletal muscle with an increased incorporation of [3H]tyrosine into protein indicating an accelerated protein synthesis. Changes in protein metabolism were paralleled by alterations in the amino acid pattern of this tissue. 3. When protein concentration and protein synthesis were increased in skeletal muscle, protein concentration of small intestine was decreased, accompanied by elevated levels of amino acids in tissue. Protein synthesis of small intestine was not altered by the norleucine treatment. The results suggest a close interrelationship between skeletal muscle and small intestine with respect to protein turnover. 4. The effects of norleucine were less pronounced at 10 and 15 days of age, which indicates a metabolic adaptation to the treatment. 5. Alterations in amino acid concentrations of tissue due to changes in protein metabolism were not uniform but tissue-specific. 6. Current concepts for explaining the effects of branched-chain amino acids (BCAA) on protein turnover in skeletal muscle are based on the assumption that the BCAA or leucine alone might become rate-limiting for protein synthesis in muscle under catabolic conditions. The amino acid analogue norleucine, however, cannot replace any of the BCAA in protein. Additionally, norleucine affected protein metabolism in highly anabolic organisms. Therefore, the present thoughts on this issue appear to be incomplete.

Amino Acid and Protein Metabolism During Differentiation (Sclerotization) of the Myxomycete Physarum flavicomum

1975 ◽  
Vol 53 (8) ◽  
pp. 834-843 ◽  
Author(s):  
Henry R. Henney Jr. ◽  
Glenna Maxey
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Metabolism ◽  
Cellular Proteins ◽  
Transport Systems ◽  
Differentiation Process ◽  
Cell Pool ◽  
Intracellular Amino Acids ◽  
Differentiation Period

Protein synthesized by growing plasmodia of Physarum flavicomum was steadily degraded when the plasmodia were induced to differentiate (form sclerotia). Protein synthesis occurred during the initial one-fifth (9 h) of the 48 h differentiation period, but most of this protein was also degraded shortly after its synthesis. Amino acids were primary catabolites during the differentiation process, and catabolism was extensive, even in the presence of dextrose. Glutamic acid was catabolized at a rate about two and a half or three times greater, respectively, than that observed for valine and arginine. Active transport systems for amino acids appeared to be present and to remain functional in P. flavicomum during differentiation. Amino acids included in the sclerotization media were rapidly accumulated into the cell pool and protein fractions. Intracellular amino acids were actively retained and were not released into the medium during differentiation.Differentiation of this Myxomycete, therefore, is characterized by a change in the metabolism of the sclerotizing plasmodium to an autolytic type, as cellular proteins and amino acids are actively catabolized during the formation of the dormant sclerotia.

Regulation of protein synthesis in lung by amino acids and insulin

1983 ◽  
Vol 245 (5) ◽  
pp. E508-E514
Author(s):  
J. M. Besterman ◽  
C. A. Watkins ◽  
D. E. Rannels
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Rat Plasma ◽  
Colloid Osmotic Pressure ◽  
Atp Depletion ◽  
Concentration Addition ◽  
Amino Acid Availability ◽  
Amino Acid Concentrations

Acute effects of amino acid availability and insulin on protein synthesis were investigated in rat lungs perfused in situ with buffer containing either 4.5% fraction V bovine serum albumin (FrV BSA), 4.5% essentially fatty acid-free (FAF) BSA, or 4.5% dextran to maintain colloid osmotic pressure. In the presence of FrV BSA, protein synthesis was unaffected by perfusion for 1 or 3 h with buffer containing no added amino acids (0X), as compared with amino acids at concentrations one (1X) or five (5X) times those in rat plasma. Regardless of the amino acid concentration, addition of insulin was without effect. Likewise, in lungs perfused for 1 h with either FAF BSA or dextran, protein synthesis was insensitive to amino acid availability or to insulin. After 3 h, however, protein synthesis decreased 34 and 37%, respectively, when these lungs were perfused in the absence of both amino acids and insulin. In both cases, the inhibition was prevented by addition of insulin to the perfusate; addition of the hormone to perfusate containing 1X amino acids or elevating perfusate amino acids to 5X did not affect protein synthesis. The deficit in protein synthesis observed in the absence of both amino acids and insulin was not accompanied by ATP depletion or by lower intracellular concentrations of amino acids. Similarly, the effect of insulin was not associated with a general elevation in intracellular amino acid concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Somatotropin-induced protein anabolism in hindquarters and portal-drained viscera of growing pigs

2003 ◽  
Vol 284 (2) ◽  
pp. E302-E312 ◽  
Author(s):  
Jill A. Bush ◽  
Douglas G. Burrin ◽  
Agus Suryawan ◽  
Pamela M. J. O'Connor ◽  
Hanh V. Nguyen ◽  
...  
Keyword(s):  
Blood Flow ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Degradation ◽  
Protein Metabolism ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Growing Pigs ◽  
Whole Body ◽  
Fed State

To differentiate the effect of somatotropin (ST) treatment on protein metabolism in the hindquarter (HQ) and portal-drained viscera (PDV), growing swine ( n = 20) treated with ST (0 or 150 μg · kg−1 · day−1) for 7 days were infused intravenously with NaH13CO3 and [2H5]phenylalanine and enterally with [1-13C]phenylalanine while in the fed state. Arterial, portal venous, and vena cava whole blood samples, breath samples, and blood flow measurements were obtained for determination of tissue and whole body phenylalanine kinetics under steady-state conditions. In the fed state, ST treatment decreased whole body phenylalanine flux, oxidation, and protein degradation without altering protein synthesis, resulting in an improvement in whole body net protein balance. Blood flow to the HQ (+80%), but not to the PDV, was increased with ST treatment. In the HQ and PDV, ST increased phenylalanine uptake (+44 and +23%, respectively) and protein synthesis (+43 and +41%, respectively), with no effect on protein degradation. In ST-treated and control pigs, phenylalanine was oxidized in the PDV (34–43% of enteral and arterial sources) but not the HQ. In both treatment groups, dietary (40%) rather than arterial (10%) extraction of phenylalanine predominated in gut amino acid metabolism, whereas localized blood flow influenced HQ amino acid metabolism. The results indicate that ST increases protein anabolism in young, growing swine by increasing protein synthesis in the HQ and PDV, with no effect on protein degradation. Differing results between the whole body and the HQ and PDV suggest that the effect of ST treatment on protein metabolism is tissue specific.

Whole body protein kinetics in women: effect of pregnancy and IDDM during anabolic stimulation

2000 ◽  
Vol 279 (5) ◽  
pp. E978-E988 ◽  
Author(s):  
Paul G. Whittaker ◽  
Choy H. Lee ◽  
Roy Taylor
Keyword(s):  
Amino Acids ◽  
Type 1 Diabetes ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Metabolism ◽  
Whole Body ◽  
Protein Breakdown ◽  
Body Protein ◽  
In Pregnancy

The effects of pregnancy and type 1 diabetes [insulin-dependent diabetes mellitus (IDDM)] on protein metabolism are still uncertain. Therefore, six normal and five IDDM women were studied during and after pregnancy, using [13C]leucine and [2H5]phenylalanine with a hyperinsulinemic-euglycemic clamp and amino acid infusion. Fasting total plasma amino acids were lower in pregnancy in normal but not IDDM women (2,631 ± 427 vs. 2,057 ± 471 and 2,523 ± 430 vs. 2,500 ± 440 μmol/l, respectively). Whole body protein breakdown (leucine) increased in pregnancy [change in normal (ΔN) and IDDM women (ΔD) 0.59 ± 0.40 and 0.48 ± 0.26 g · kg−1 · day−1, both P < 0.001], whereas reductions in protein breakdown due to insulin/amino acids (ΔN −0.57 ± 0.19, ΔD −0.58 ± 0.20 g · kg−1 · day−1, both P < 0.001) were unaffected by pregnancy. Protein breakdown in IDDM women was not higher than normal, and neither pregnancy nor type 1 diabetes altered the insulin sensitivity of amino acid turnover. Nonoxidized leucine disposal (protein synthesis) increased in pregnancy (ΔN 0.67 ± 0.45, ΔD 0.64 ± 0.34 g · kg−1 · day−1, both P < 0.001). Pregnancy reduced the response of phenylalanine hydroxylation to insulin/amino acids in both groups (ΔN −1.14 ± 0.74, ΔD −1.12 ± 0.77 g · kg−1 · day−1, both P < 0.05). These alterations may enable amino acid conservation for protein synthesis and accretion in late pregnancy. Well-controlled type 1 diabetes caused no abnormalities in the regulation of basal or stimulated protein metabolism.

scholarly journals Amino acid-induced stimulation of translation initiation in rat skeletal muscle

1999 ◽  
Vol 277 (6) ◽  
pp. E1077-E1086 ◽  
Author(s):  
Thomas C. Vary ◽  
Leonard S. Jefferson ◽  
Scot R. Kimball
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Translation Initiation ◽  
Amino Acid Supplementation ◽  
Initiation Factors ◽  
Eukaryotic Initiation Factors ◽  
Amino Acid Concentrations ◽  
Stimulation Of

Amino acids stimulate protein synthesis in skeletal muscle by accelerating translation initiation. In the two studies described herein, we examined mechanisms by which amino acids regulate translation initiation in perfused skeletal muscle hindlimb preparation of rats. In the first study, the effects of supraphysiological amino acid concentrations on eukaryotic initiation factors (eIF) 2B and 4E were compared with physiological concentrations of amino acids. Amino acid supplementation stimulated protein synthesis twofold. No changes were observed in eIF2B activity, in the amount of eIF4E associated with the eIF4E-binding protein (4E-BP1), or in the phosphorylation of 4E-BP1. The abundance of eIF4E bound to eIF4G and the extent of phosphorylation of eIF4E were increased by 800 and 20%, respectively. In the second study, we examined the effect of removing leucine on translation initiation when all other amino acids were maintained at supraphysiological concentrations. Removal of leucine from the perfusate decreased the rate of protein synthesis by 40%. The inhibition of protein synthesis was associated with a 40% decrease in eIF2B activity and an 80% fall in the abundance of eIF4E ⋅ eIF4G complex. The fall in eIF4G binding to eIF4E was associated with increased 4E-BP1 bound to eIF4E and a reduced phosphorylation of 4E-BP1. In contrast, the extent of phosphorylation of eIF4E was unaffected. We conclude that formation of the active eIF4E ⋅ eIF4G complex controls protein synthesis in skeletal muscle when the amino acid concentration is above the physiological range, whereas removal of leucine reduces protein synthesis through changes in both eIF2B and eIF4E.

Human soleus and vastus lateralis muscle protein metabolism with an amino acid infusion

2005 ◽  
Vol 288 (3) ◽  
pp. E479-E485 ◽  
Author(s):  
Chad C. Carroll ◽  
James D. Fluckey ◽  
Rick H. Williams ◽  
Dennis H. Sullivan ◽  
Todd A. Trappe
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Resistance Exercise ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Vastus Lateralis ◽  
Translational Initiation ◽  
Acid Infusion ◽  
Amino Acid Infusion

The calf muscles, compared with the thigh, are less responsive to resistance exercise in ambulatory and bed-rested individuals, apparently due to muscle-specific differences in protein metabolism. We chose to evaluate the efficacy of using amino acids to elevate protein synthesis in the soleus, because amino acids have been shown to have a potent anabolic effect in the vastus lateralis. Mixed muscle protein synthesis in the soleus and vastus lateralis was measured before and after infusion of mixed amino acids in 10 individuals (28 ± 1 yr). Phosphorylation of ribosomal protein p70 S6 kinase (p70S6K; Thr389) and eukaryotic initiation factor 4E-binding protein-1 (4E-BP1; Thr37/46) was also evaluated at rest and after 3 h of amino acid infusion. Basal protein synthesis was similar ( P = 0.126), and amino acids stimulated protein synthesis to a similar extent ( P = 0.004) in the vastus lateralis (0.043 ± 0.011%/h) and soleus (0.032 ± 0.017%/h). Phosphorylation of p70S6K ( P = 0.443) and 4E-BP1 ( P = 0.192) was not increased in either muscle; however, the soleus contained more total ( P = 0.002) and phosphorylated ( P = 0.013) 4E-BP1 than the vastus lateralis. These data support the need for further study of amino acid supplementation as a means to compensate for the reduced effectiveness of calf resistance exercise in ambulatory individuals and those exposed to extended periods of unloading. The greater 4E-BP1 in the soleus suggests that there is a muscle-specific distribution of general translational initiation machinery in human skeletal muscle.

AL Ternate Use of Amino Acid and Glucose Solutions in CAPD

1985 ◽  
Vol 5 (4) ◽  
pp. 215-218 ◽  
Author(s):  
Fritz Bangsgaard Pedersen ◽  
Claus Dragsholt ◽  
Erik Laier ◽  
Jens Jurgen ◽  
Frifelt Aage ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Glycosylated Hemoglobin ◽  
Ammonium Concentration ◽  
Uremic Patient ◽  
Amino Acid Supplementation ◽  
Serum Triglycerides ◽  
Isoleucine Leucine ◽  
Amino Acid Concentrations

For three months we alternately used CAPD solutions based on amino acids or glucose in six patients. At the start, amino acid concentrations in plasma (P) were normal, except that for leucine which was low and citrulline was high. During the study, P-valine, -isoleucine, -leucine, and -serine increased while the concentration of methionine decreased. The increase in the plasma concentration of the three branched-chain amino acids might increase protein synthesis; leucine particularly assists protein synthesis in muscle. However the technical and analytical methods used in this investigation do not permit us to draw such conclusions. Serum concentrations of cholesterol, HDL, LDL, glucose and glycosylated hemoglobin remained unchanged, as did concentrations of albumin, transferrin, and phosphate. The nitrogen load from amino acids did not increase the plasma ammonium concentration, while serum urea increased slightly. Serum triglycerides continued to increase in spite of the amino acid supplementation. Thus the amino acid solution, which was well tolerated, seemed to induce some beneficial alterations in the plasma amino acid concentrations in the uremic patient. The consequence of these changes remains to be evaluated.

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