scholarly journals Effects of experimental hyperthyroidism on protein turnover in skeletal and cardiac muscle as measured by [14C]tyrosine infusion

1982 ◽  
Vol 204 (1) ◽  
pp. 69-74 ◽  
Author(s):  
W J Carter ◽  
W S V W Benjamin ◽  
F H Faas
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Cardiac Muscle ◽  
Heart Muscle ◽  
Protein Turnover ◽  
Cardiac Myocyte ◽  
Muscle Protein ◽  
Muscle Growth ◽  
Protein Breakdown ◽  
Fractional Rate

The effect of T3 (3,3′,5-tri-iodothyronine) on protein turnover in skeletal and cardiac muscle was measured in intact rats by means of a 6 h [14C]tyrosine-infusion technique. Treatment with 25-30 micrograms of T3/100 g body wt. daily for 4-7 days increased the fractional rate of protein synthesis in skeletal muscle. Since the fractional growth rate of the muscle was decreased or unchanged, T3 treatment increased the rate of muscle protein breakdown. These findings suggest that increased protein degradation is an important factor in decreasing skeletal-muscle mass in hyperthyroidism. In contrast with skeletal muscle, T3 treatment for 7 days caused an equivalent increase in the rate of cardiac muscle growth and protein synthesis. This suggests that hyperthyroidism does not increase protein breakdown in heart muscle as it does in skeletal muscle. The failure of T3 to increase proteolysis in heart muscle may be due to a different action on the cardiac myocyte or to systemic effects of T3 which increase cardiac work.

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.

scholarly journals Skeletal-muscle growth and protein turnover

1975 ◽  
Vol 150 (2) ◽  
pp. 235-243 ◽  
Author(s):  
D J Millward ◽  
P J Garlick ◽  
R J C Stewart ◽  
D O Nnanyelugo ◽  
J C Waterlow
Keyword(s):  
Skeletal Muscle ◽  
Growth Rate ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Growth ◽  
Muscle Size ◽  
Synthesis Rate ◽  
Protein Breakdown ◽  
Breakdown Rate ◽  
Breakdown Rates

Because of turnover, protein synthesis and breakdown can each be involved in the regulation of the growth of tissue protein. To investigate the regulation of skeletal-muscle-protein growth we measured rates of protein synthesis and breakdown in growing rats during development on a good diet, during development on a marginally low-protein diet and during rehabilitation on a good diet after a period of severe protein deficiency. Rates of protein synthesis were measured in vivo with a constant intravenous infusion of [14C]tyrosine. The growth rate of muscle protein was measured and the rate of breakdown calculated as breakdown rate=synthesis rate-growth rate. These measurements showed that during development on a good diet there was a fall with age in the rate of protein synthesis resulting from a fall in capacity (RNA concentration) and activity (synthesis rate per unit of RNA). There was a fall with age in the breakdown rate so that the rate was highest in the weaning rats, with a half-life of 3 days. There was a direct correlation between the fractional growth and breakdown rates. During rehabilitation on the good diet, rapid growth was also accompanied by high rates of protein breakdown. During growth on the inadequate diet protein synthesis rates were lesss than in controls, but growth occurred because of decreased rates of protein breakdown. This compression was not complete, however, since ultimate muscle size was only one-half that of controls. It is suggested that increased rates of protein breakdown are a necessary accompaniment to muscle growth and may result from the way in which myofibrils proliferate.

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.

Skeletal and heart muscle protein turnover during long-term exposure to high environmental temperatures in young rats

2000 ◽  
Vol 78 (7) ◽  
pp. 557-564 ◽  
Author(s):  
S E Samuels ◽  
T A McAllister ◽  
J R Thompson
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Mass ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Control Group ◽  
Skeletal Muscle Protein ◽  
Protein Mass ◽  
Fractional Rate

A study was undertaken to determine the long-term effects of a hot environment on protein turnover in skeletal and cardiac muscles of young homeothermic animals. Three groups of 36 male 28 day old rats were housed at 35°C (hot group), 25°C (control group), or 25°C but pair-fed to the intake of the hot group (pair-fed group). Rates of protein synthesis and degradation were measured in vivo on days 5, 10, 15, and 20. By day 20, soleus and gastrocnemius (skeletal muscle) protein masses were 7 and 14% lower in the hot group and 31 and 21% lower in the pair-fed group compared with the control group (P < 0.05). The fractional rate of protein synthesis (ksyn) was on average 11% lower (P < 0.05) in the hot group compared with control rats and was not different from pair-fed rats. The fractional rate of skeletal muscle protein degradation (kdeg) in hot rats was slightly lower than in control rats; kdegwas on average 18% higher (P < 0.05) in the pair-fed group compared with the hot group and this difference appeared to be most prominent on day 5. In heart, by day 20, protein mass was 30% lower in the hot group and 40% lower in the pair-fed group compared with control rats (P < 0.05). ksynwas on average 19% lower (P < 0.05) in the hot group compared with the control group, but not different from pair-fed rats. In the heart there were no differences in kdegamong treatments. Plasma triiodothyronine (T3) concentration was lower in the hot group, but not in the pair-fed group, compared with controls. In conclusion, chronic exposure to hot environments was associated with lower skeletal and cardiac muscle mass and protein turnover; lower protein mass in this tissue was due to decreased ksyn; this is consistent with lower plasma T3concentrations. In pair-fed rats, ksynwas also reduced, but interestingly kdegwas not, resulting in a greater loss of skeletal muscle mass. These results suggest that heat exposure invokes physiological adaptations to preserve skeletal muscle mass despite decreased food intake. In the heart, loss of protein was a result of decreased ksyn, which can be primarily ascribed to lower food intake.Key words: protein synthesis, protein metabolism, acclimation, heat stress.

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.

Protein metabolism in cardiac hypertrophy and heart failure

1964 ◽  
Vol 206 (2) ◽  
pp. 294-298 ◽  
Author(s):  
Sigmundur Gudbjarnason ◽  
Michael Telerman ◽  
Richard J. Bing
Keyword(s):  
Heart Failure ◽  
Protein Synthesis ◽  
Chronic Heart Failure ◽  
Cardiac Hypertrophy ◽  
Protein Metabolism ◽  
Heart Muscle ◽  
Protein Turnover ◽  
Turnover Rate ◽  
Muscle Protein ◽  
Myocardial Failure

The rate of myocardial protein synthesis was studied in hearts of normal rabbits and in hearts of animals with experimentally produced cardiac hypertrophy and with acute and chronic myocardial failure. Cardiac hypertrophy was accompanied by an increase in protein synthesis; however, there was no increased myocardial protein turnover rate. In acute heart failure the rate of myocardial protein synthesis was diminished as compared to protein synthesis during the development of cardiac hypertrophy. In chronic heart failure the relative incorporation of glycine-2-C14 into heart muscle protein was diminished. The turnover rate of myocardial proteins during cardiac hypertrophy was not altered.

scholarly journals Treatment of burned rats with insulin-like growth factor I inhibits the catabolic response in skeletal muscle

1998 ◽  
Vol 275 (4) ◽  
pp. R1091-R1098 ◽  
Author(s):  
Cheng-Hui Fang ◽  
Bing-Guo Li ◽  
Jing Jing Wang ◽  
Josef E. Fischer ◽  
Per-Olof Hasselgren
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Burn Injury ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Protein Breakdown ◽  
Turnover Rates ◽  
Breakdown Rates ◽  
Igf I ◽  
Catabolic Response

Thermal injury is associated with a pronounced catabolic response in skeletal muscle, reflecting inhibited protein synthesis and increased protein breakdown, in particular myofibrillar protein breakdown. Administration of insulin-like growth factor I (IGF-I) has a nitrogen-sparing effect after burn injury, but the influence of this treatment on protein turnover rates in skeletal muscle is not known. In the present study, we examined the effect of IGF-I on muscle protein synthesis and breakdown rates following burn injury in rats. After a 30% total body surface area burn injury or sham procedure, rats were treated with a continuous infusion of IGF-I (3.5 or 7 mg ⋅ kg−1 ⋅ 24 h−1) for 24 h. Protein synthesis and breakdown rates were determined in incubated extensor digitorum longus muscles. Burn injury resulted in increased total and myofibrillar protein breakdown rates and reduced protein synthesis in muscle. The increase in protein breakdown rates was blocked by both doses of IGF-I and the burn-induced inhibition of muscle protein synthesis was partially reversed by the higher dose of the hormone. IGF-I did not influence muscle protein turnover rates in nonburned rats. The results suggest that the catabolic response to burn injury in skeletal muscle can be inhibited by IGF-I.

scholarly journals The effects of calcium on protein turnover in skeletal muscles of the rat

1982 ◽  
Vol 204 (1) ◽  
pp. 257-264 ◽  
Author(s):  
S E M Lewis ◽  
P Anderson ◽  
D F Goldspink
Keyword(s):  
Protein Synthesis ◽  
Cyclic Nucleotides ◽  
Protein Turnover ◽  
Skeletal Muscles ◽  
Extensor Digitorum Longus ◽  
Muscle Protein ◽  
Ionophore A23187 ◽  
Protein Breakdown ◽  
External Concentration ◽  
The Media

Several experimental procedures were used to increase the intracellular concentration of Ca2+ and determine its effects on protein turnover in isolated extensor digitorum longus and soleus muscle. These methods included the use of ionophore A23187, caffeine, dibucaine, thymol and procaine, all agents known to induce the release of calcium by acting either on the sarcolemma and/or on the sarcoplasmic reticulum. Another approach involved varying the external concentration of Ca2+ in the media in which the muscles were incubated. The changes in muscle Ca2+ concentrations after exposure to the various calcium-releasing agents were in keeping with accepted modes of action of these agents on muscle membranes. The findings suggest that increasing the sarcoplasmic concentration of Ca2+ inhibits protein synthesis and enhances protein breakdown. These catabolic effects of Ca2+ are compared with the changes induced in muscle protein turnover after exposure to insulin or cyclic nucleotides, and in myopathic muscle and situations of work overload. Attention is also drawn to some of the difficulties involved in definitively implicating Ca2+ as a factor involved in the normal regulation of protein turnover.

scholarly journals Skeletal muscle and resistance exercise training; the role of protein synthesis in recovery and remodeling

2017 ◽  
Vol 122 (3) ◽  
pp. 541-548 ◽  
Author(s):  
Chris McGlory ◽  
Michaela C. Devries ◽  
Stuart M. Phillips
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Protein Turnover ◽  
Potential Role ◽  
Muscle Protein ◽  
Short Review ◽  
Translational Efficiency ◽  
Exercise Science ◽  
Resistance Exercise Training

Exercise results in the rapid remodeling of skeletal muscle. This process is underpinned by acute and chronic changes in both gene and protein synthesis. In this short review we provide a brief summary of our current understanding regarding how exercise influences these processes as well as the subsequent impact on muscle protein turnover and resultant shift in muscle phenotype. We explore concepts of ribosomal biogenesis and the potential role of increased translational capacity vs. translational efficiency in contributing to muscular hypertrophy. We also examine whether high-intensity sprinting-type exercise promotes changes in protein turnover that lead to hypertrophy or merely a change in mitochondrial content. Finally, we propose novel areas for future study that will fill existing knowledge gaps in the fields of translational research and exercise science.

Changes in protein turnover in rat uterus during pregnancy

1986 ◽  
Vol 250 (2) ◽  
pp. E114-E120 ◽  
Author(s):  
A. J. Morton ◽  
D. F. Goldspink
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Turnover ◽  
Cathepsin D ◽  
Cell Loss ◽  
Protein Breakdown ◽  
Rat Uterus ◽  
Fractional Rate ◽  
Uterine Growth

The adaptive growth and protein turnover of the rat uterus were studied during the 21 days of gestation and up to 3 days after parturition. Despite large increases (13-fold) in uterine size during gestation, the fractional rate of protein synthesis (measured in vivo) remained unchanged when compared with nonpregnant tissue values of 44 +/- 5%/day. However, decreases were found in the rate of protein breakdown after implantation (i.e., 75% on day 7 and 28% on day 11) and in the activity of cathepsin D (i.e., 33 and 85% on days 8 and 16 of gestation). Changes in the degradative processes would therefore appear to be primarily responsible for the massive uterine growth during pregnancy. In contrast to the uterus the fractional rates of synthesis in the placenta and fetus progressively decreased during gestation. After parturition the uterus rapidly returned to its normal size by a combination of cellular atrophy and cell loss. After 2 days, a complementary decrease in the fractional rate of synthesis (30%) and an increase in protein degradation (2-fold) explained the process of involution.

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