scholarly journals Protein turnover of breast muscle in germ-free and conventional chicks

1985 ◽  
Vol 54 (1) ◽  
pp. 131-145 ◽  
Author(s):  
T. Muramatsu ◽  
D. N. Salter ◽  
M. E. Coates
Keyword(s):  
Protein Turnover ◽  
Time Course ◽  
Pectoral Muscle ◽  
Breast Muscle ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Absolute Amount ◽  
Gut Microflora ◽  
Isotopic Equilibrium ◽  
The Absolute

1. The effect of the gut microflora on protein turnover in pectoral muscle (M. pectoralis profundus) was studied by means of dietary infusion of L-[UJ-14C]phenylalanine and of massive dose injection of L-[4-3H]phenylalanine in chicks fed on a semi-purified casein—gelatin (SCG) diet until 19 d of age, and in those subsequently given either a nitrogen-free (NF) diet or NF supplemented with methionine and arginine (MA) for a further 9 d.2. Time-course changes in radioactivity released in expired carbon dioxide during the 8 h infusion period showed that isotopic equilibrium was reached in 4 h with the SCG diet and in 5 h with the MA diet. However, with the protein-deprived chicks given the NF diet, isotopic equilibrium was not achieved since radioactivity in CO2 increased linearly throughout.3. On feeding the NF diet, fractional protein synthesis rate and the absolute amount of protein synthesized in chick breast muscle were reduced. These reductions were partially alleviated by supplementing the NF diet with methionine and arginine.4. The fractional degradation rate of breast muscle was increased in chicks given the NF diet, while the absolute amount of protein degraded was decreased. The addition of methionine and arginine counteracted these changes brought about by protein starvation.5. Generally speaking, the presence of the gut microflora had little, if any, effect on protein turnover rate in chick-breast muscle.

scholarly journals The effect of protein depletion and repletion on muscle-protein turnover in the chick

1981 ◽  
Vol 194 (3) ◽  
pp. 811-819 ◽  
Author(s):  
M L MacDonald ◽  
R W Swick
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Control Diet ◽  
Breast Muscle ◽  
Synthesis Rate ◽  
Protein Depletion ◽  
Protein Mass ◽  
Fractional Rate

Rates of growth and protein turnover in the breast muscle of young chicks were measured in order to assess the roles of protein synthesis and degradation in the regulation of muscle mass. Rates of protein synthesis were measured in vivo by injecting a massive dose of L-[1-14C]valine, and rates of protein degradation were estimated as the difference between the synthesis rate and the growth rate of muscle protein. In chicks fed on a control diet for up to 7 weeks of age, the fractional rate of synthesis decreased from 1 to 2 weeks of age and then changed insignificantly from 2 to 7 weeks of age, whereas DNA activity was constant for 1 to 7 weeks. When 4-week-old chicks were fed on a protein-free diet for 17 days, the total amount of breast-muscle protein synthesized and degraded per day and the amount of protein synthesized per unit of DNA decreased. Protein was lost owing to a greater decrease in the rate of protein synthesis, as a result of the loss of RNA and a lowered RNA activity. When depleted chicks were re-fed the control diet, rapid growth was achieved by a doubling of the fractional synthesis rate by 2 days. Initially, this was a result of increased RNA activity; by 5 days, the RNA/DNA ratio also increased. There was no evidence of a decrease in the fractional degradation rate during re-feeding. These results indicate that dietary-protein depletion and repletion cause changes in breast-muscle protein mass primarily through changes in the rate of protein synthesis.

Effects of low-dose leucine supplementation on gastrocnemius muscle mitochondrial content and protein turnover in tumor-bearing mice

2019 ◽  
Vol 44 (9) ◽  
pp. 997-1004 ◽  
Author(s):  
Harold W. Lee ◽  
Ella Baker ◽  
Kevin M. Lee ◽  
Aaron M. Persinger ◽  
William Hawkins ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Mitochondrial Biogenesis ◽  
Protein Turnover ◽  
C2c12 Myotubes ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Mitochondrial Content ◽  
Leucine Supplementation ◽  
Tumor Bearing

Many forms of cancer are associated with loss of lean body mass, commonly attributed to decreased protein synthesis and stimulation of proteolytic pathways within the skeletal muscle. Leucine has been shown to improve protein synthesis, insulin signaling, and mitochondrial biogenesis, which are key signaling pathways influenced by tumor signaling. The purpose of this study was to examine the effects of leucine supplementation on mitochondrial biogenesis and protein turnover in tumor-bearing mice. Twenty male C57BL/6 mice were divided into 4 groups (n = 5): Chow, leucine (Leu), Lewis lung carcinoma (LLC) implant, and LLC+Leu. At 9–10 weeks of age, mice were inoculated and supplemented with 5% leucine (w/w) in the diet. C2C12 myotubes were treated with 2.5 mmol/L leucine and 25% LLC conditioned media to further elucidate the direct influence of the tumor and leucine on the muscle. Measures of protein synthesis, mitochondrial biogenesis, and inflammation in the gastrocnemius were assessed via Western blot analysis. Gastrocnemius mass was decreased in LLC+Leu relative to LLC (p = 0.040). Relative protein synthesis rate was decreased in LLC mice (p = 0.001). No change in protein synthesis was observed in myotubes. Phosphorylation of STAT3 was decreased in the Leu group relative to the control in both mice (p = 0.019) and myotubes (p = 0.02), but did not significantly attenuate the inflammatory effect of LLC implantation (p = 0.619). LLC decreased markers of mitochondrial content; however, PGC-1α was increased in LLC+Leu relative to LLC (p = 0.001). While leucine supplementation was unable to preserve protein synthesis or mitochondrial content associated with LLC implantation, it was able to increase mitochondrial biogenesis signaling. Novelty This study provides novel insights on the effect of leucine supplementation on mitochondrial biogenesis and protein turnover in tumor-bearing mice. Leucine increased signaling for mitochondrial biogenesis in the skeletal muscle. Leucine supplementation decreased inflammatory signaling in skeletal muscle.

Regulation of myofibrillar protein turnover during maturation in normal and undernourished rat pups

2000 ◽  
Vol 278 (4) ◽  
pp. R845-R854 ◽  
Author(s):  
Marta L. Fiorotto ◽  
Teresa A. Davis ◽  
Peter J. Reeds
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Myofibrillar Protein ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Myofibrillar Proteins ◽  
Sarcoplasmic Proteins ◽  
Rat Pups ◽  
Sarcoplasmic Protein ◽  
Degradation Rates

The study tested the hypothesis that a higher rate of myofibrillar than sarcoplasmic protein synthesis is responsible for the rapid postdifferentiation accumulation of myofibrils and that an inadequate nutrient intake will compromise primarily myofibrillar protein synthesis. Myofibrillar (total and individual) and sarcoplasmic protein synthesis, accretion, and degradation rates were measured in vivo in well-nourished (C) rat pups at 6, 15, and 28 days of age and compared at 6 and 15 days of age with pups undernourished (UN) from birth. In 6-day-old C pups, a higher myofibrillar than sarcoplasmic protein synthesis rate accounted for the greater deposition of myofibrillar than sarcoplasmic proteins. The fractional synthesis rates of both protein compartments decreased with age, but to a greater degree for myofibrillar proteins (−54 vs. −42%). These decreases in synthesis rates were partially offset by reductions in degradation rates, and from 15 days, myofibrillar and sarcoplasmic proteins were deposited in constant proportion to one another. Undernutrition reduced both myofibrillar and sarcoplasmic protein synthesis rates, and the effect was greater at 6 (−25%) than 15 days (−15%). Decreases in their respective degradation rates minimized the effect of undernutrition on sarcoplasmic protein accretion from 4 to 8 days and on myofibrillar proteins from 13 to 17 days. Although these adaptations in protein turnover reduced overall growth of muscle mass, they mitigated the effects of undernutrition on the normal maturational changes in myofibrillar protein concentration.

Measurement of plasma protein synthesis rate in infant pig: an investigation of alternative tracer approaches

1994 ◽  
Vol 267 (1) ◽  
pp. R221-R227 ◽  
Author(s):  
F. Jahoor ◽  
D. G. Burrin ◽  
P. J. Reeds ◽  
M. Frazer
Keyword(s):  
Protein Synthesis ◽  
Plasma Protein ◽  
Apolipoprotein B ◽  
Plasma Proteins ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Isotopic Equilibrium ◽  
Fractional Synthesis

To devise a new method to measure plasma protein synthesis, we tested the hypothesis that, when [U-13C]glucose is used to produce [U-13C]alanine, plasma pyruvate and alanine will be in isotopic equilibrium with the alanine used to synthesize plasma proteins. The incorporation of labeled leucine, lysine, and alanine into very-low-density lipoprotein (VLDL) apolipoprotein B (apoB)-100, albumin, and fibrinogen was measured in seven infant pigs by infusing [U-13C]glucose, [2H3]leucine, and [2H4]lysine. The plateau enrichments of plasma alanine (2.29 +/- 0.29), pyruvate (2.5 +/- 0.33), and apoB-alanine (2.33 +/- 0.25) were not different. The fractional synthesis rates of fibrinogen and albumin calculated using the isotopic enrichments of apoB-bound lysine, leucine, and alanine as the precursor were similar to those based on plasma alanine. These results suggest that the intrahepatic precursor alanine pool and plasma alanine were in isotopic equilibrium. Thus plasma protein synthesis can be measured by infusing [U-13C]glucose and using plasma alanine as precursor.

scholarly journals Rates of protein turnover in vivo and in vitro in ventricular muscle of hearts from fed and starved rats

1984 ◽  
Vol 222 (2) ◽  
pp. 395-400 ◽  
Author(s):  
V R Preedy ◽  
D M Smith ◽  
N F Kearney ◽  
P H Sugden
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Turnover ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Ventricular Muscle ◽  
Degradation Rates ◽  
Perfused Hearts

Starvation of 300 g rats for 3 days decreased ventricular-muscle total protein content and total RNA content by 15 and 22% respectively. Loss of body weight was about 15%. In glucose-perfused working rat hearts in vitro, 3 days of starvation inhibited rates of protein synthesis in ventricles by about 40-50% compared with fed controls. Although the RNA/protein ratio was decreased by about 10%, the major effect of starvation was to decrease the efficiency of protein synthesis (rate of protein synthesis relative to RNA). Insulin stimulated protein synthesis in ventricles of perfused hearts from fed rats by increasing the efficiency of protein synthesis. In vivo, protein-synthesis rates and efficiencies in ventricles from 3-day-starved rats were decreased by about 40% compared with fed controls. Protein-synthesis rates and efficiencies in ventricles from fed rats in vivo were similar to values in vitro when insulin was present in perfusates. In vivo, starvation increased the rate of protein degradation, but decreased it in the glucose-perfused heart in vitro. This contradiction can be rationalized when the effects of insulin are considered. Rates of protein degradation are similar in hearts of fed animals in vivo and in glucose/insulin-perfused hearts. Degradation rates are similar in hearts of starved animals in vivo and in hearts perfused with glucose alone. We conclude that the rates of protein turnover in the anterogradely perfused rat heart in vitro closely approximate to the rates in vivo in absolute terms, and that the effects of starvation in vivo are mirrored in vitro.

scholarly journals Human cells adapt to translational errors by modulating protein synthesis rate and protein turnover

RNA Biology ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 135-149 ◽  
Author(s):  
Ana Sofia Varanda ◽  
Mafalda Santos ◽  
Ana R. Soares ◽  
Rui Vitorino ◽  
Patrícia Oliveira ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Human Cells ◽  
Synthesis Rate ◽  
Protein Synthesis Rate

Protein kinetics in stable heart failure patients

2003 ◽  
Vol 94 (1) ◽  
pp. 295-300 ◽  
Author(s):  
Charles W. Cortes ◽  
Paul D. Thompson ◽  
Niall M. Moyna ◽  
Margaret D. Schluter ◽  
Maria J. Leskiw ◽  
...  
Keyword(s):  
Protein Metabolism ◽  
Protein Turnover ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Bed Rest ◽  
Whole Body ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Body Protein ◽  
Fractional Synthesis

Heart failure (HF) is a slow progressive syndrome characterized by low cardiac output and peripheral metabolic, biochemical, and histological alterations. Protein loss and reduced protein turnover occur with aging, but the consequences of congestive HF (CHF) superimposed on the normal aging response are unknown. This study has two objectives: 1) to determine whether there was a difference between older age-matched controls and those with stable HF (i.e., ischemic pathology) in whole body protein turnover and 2) to determine whether protein metabolism in liver and skeletal muscle protein turnover is impacted by CHF. We measured the whole body protein synthesis rate with a U-15N-labeled algal protein hydrolysate in 10 patients with CHF and in 10 age-matched controls. Muscle fractional synthesis rate of lateral vastus muscle was determined with [U-13C]alanine on muscle biopsies obtained by a standard percutaneous needle biopsy technique. Fractional synthesis rates of five plasma proteins of hepatic origin (fibrinogen, complement C-3, ceruloplasmin, transferrin, and very low-density lipoprotein apoliprotein B-100) were determined by using2H5-labeled l-phenylalanine as tracer. Results showed that whole body protein synthesis rate was reduced in CHF patients (3.09 ± 0.19 vs. 2.25 ± 0.71 g protein · kg−1 · day−1, P < 0.05) as was muscle fractional synthesis rate (3.02 ± 0.58 vs. 1.33 ± 0.71%/day, P < 0.05) and very low-density lipoprotein apoliprotein B-100 (265 ± 25 vs. 197 ± 16%/day, P < 0.05). CHF patients were hyperinsulinemic (9.6 ± 3.1 vs. 47.0 ± 7.8 μU/ml, P < 0.01). The results were compared with those found with bed rest patients. In conclusion, protein turnover is depressed in CHF patients, and both skeletal muscle and liver are impacted. These results are similar to those found with bed rest, which suggests that inactivity is a factor in depressed protein metabolism.

Muscle Protein and Amino Acid Turnover in Rats in Vivo: Effects of Short-Term and Prolonged Starvation

1996 ◽  
Vol 90 (6) ◽  
pp. 457-466 ◽  
Author(s):  
I. De Blaauw ◽  
N. E. P. Deutz ◽  
M. F. Von Meyenfeldt
Keyword(s):  
Body Weight ◽  
Protein Synthesis ◽  
Protein Turnover ◽  
Gastrocnemius Muscle ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Small Animals ◽  
Prolonged Starvation ◽  
Amino Acid Turnover ◽  
Tracer Dilution

1. Protein loss in muscle can be caused by decreased protein synthesis, increased breakdown or both. In small animals the tracer incorporation technique is mostly used to measure protein synthesis, but for degradation measurements in vitro or ex vivo settings are required. In human and large animal studies the arteriovenous dilution technique is used because it enables the measurement of synthesis and breakdown rates simultaneously. The applicability in small animals has not yet been proven. We used a starvation model to compare both techniques. 2. A primed constant infusion of l-[2,6-3H]phenylalanine was given to male Lewis rats after 16, 40, 64 and 112 h starvation. Protein synthesis rates of the gastrocnemius muscle were measured by the incorporation technique and compared with hindquarter protein turnover calculated in a two- and three-compartment arteriovenous dilution model. 3. Whole-body phenylalanine rate of appearance decreased from 456 ± 32 after 16 h to 334 ± 34 (nmol min−1 100 g−1 body weight) after 112 h starvation. Protein synthesis rates of the gastrocnemius muscle measured by the tracer incorporation technique decreased from 3.6 ± 0.4 after 16 h starvation to 2.2 ± 0.3 after 64 h starvation and 1.8 ± 0.4 (%/day) after 112h starvation. Hindquarter protein breakdown, calculated with the tracer dilution model, increased after 112 h starvation from 28 ± 12 to 77 ± 15 nmol min−1 100 g−1 body weight. Using the tracer dilution model, however, the calculated protein synthesis rate across the hindquarter also increased after prolonged starvation (29 ± 7 and 68 ± 16 nmol min−1 100 g−1 body weight after 16 and 112h respectively). In conjunction with this, calculated bidirectional membrane transport rates were also enhanced. Using valine and glutamine as tracers, the enhanced amino acid turnover rates were confirmed. 4. In conclusion, our results show that during short periods of starvation both methods give similar results. After prolonged starvation, however, an opposite change in disappearance rate and protein synthesis rate was observed. Assumptions made to calculate protein turnover using the arteriovenous dilution model may account for the discrepancy and care must be taken with the interpretation when using only one model in anaesthetized small animals.

THYROXINE METABOLISM IN THE RAT: EFFECT OF VARYING DOSES OF EXOGENOUS THYROXINE

1975 ◽  
Vol 78 (4) ◽  
pp. 714-722 ◽  
Author(s):  
Valerie Anne Galton
Keyword(s):  
Body Weight ◽  
Dose Level ◽  
Fold Increase ◽  
Absolute Amount ◽  
Isotopic Equilibrium ◽  
Fractional Rate ◽  
The Absolute ◽  
Peripheral Metabolism

ABSTRACT Experiments were performed to determine quantitatively the peripheral metabolism of exogenous thyroxine T4) in rats brought to isotopic equilibrium with doses of 131I-T4 ranging from 1 to 20 μg/100 g body weight/ day. It was found that, although the absolute amount of T4 either deiodinated and excreted as iodide in urine or excreted as T4 in faeces increased as the dose of T4 increased, the percentage of hormone excreted by either pathway at each dose level was relatively constant. In other words, the fractional rate of deiodination is not greatly influenced by the amount of T4 administered. A 20-fold increase in the dose of T4 resulted in only a 4-fold increase in serum T4 concentration measured 24 h after injection, but serum T4 levels were elevated considerably more than this for several hours between injections. Nevertheless, the highest dose of T4 was not greatly thyrotoxic. The implications of these findings in relation to the possible association between the metabolism and action of T4 are discussed.

Protein metabolism and beta-myosin heavy-chain mRNA in unweighted soleus muscle

1989 ◽  
Vol 257 (2) ◽  
pp. R300-R305 ◽  
Author(s):  
D. B. Thomason ◽  
R. B. Biggs ◽  
F. W. Booth
Keyword(s):  
Protein Synthesis ◽  
Soleus Muscle ◽  
Time Course ◽  
Degradation Rate ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Hindlimb Unweighting ◽  
First Order ◽  
Degradation Rate Constant ◽  
Myofibril Protein

To investigate the relative influence of protein synthetic and degradative control mechanisms in vivo during skeletal muscle atrophy, we measured myofibril and total mixed protein synthesis rates in muscles of rats prevented from hindlimb weight-bearing for 5 h and 7 days. Protein synthesis rates were determined by infusing the animals with [3H]Leu for 5 h and measuring the specific activity of [3H]Leu in the aminoacyl-tRNA precursor and protein product fractions of the muscles. In the soleus muscle, myofibril protein synthesis rates decreased from a control value of 5.9 to 4.6%/day during 5 h of hindlimb unweighting and to 2.4%/day after 7 days of hindlimb unweighting. The relatively more phasic muscles (plantaris, medial gastrocnemius, quadriceps) showed a tendency for increased myofibril protein synthesis rates (117-127% of control) during the first 5 h followed by a decrease (46-62% of control) at 7 days of hindlimb unweighting. A predicted time course of soleus muscle myofibril protein degradation rate was obtained from a numerical model of the decrease in soleus myofibril protein synthesis rate as a first-order process [half-time (t1/2) = 0.3 day by least-squares fit] and the time course of soleus muscle myofibril protein previously observed with hindlimb unweighting (Thomason et al., J. Appl. Physiol. 63: 130-137, 1987). The degradation rate model makes specific, testable predictions for the mechanism of myofibril protein degradation during soleus muscle atrophy: 1) the first-order degradation rate constant does not obtain a fixed value over a 24-day period but is continuously changing throughout atrophy, and 2) the first-order degradation rate constant changes on a time scale slower than protein synthesis rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Sign in / Sign up

Export Citation Format

Share Document