Skeletal muscle protein synthesis and degradation in vitro: effects of temperature

1985 ◽  
Vol 249 (5) ◽  
pp. C464-C470 ◽  
Author(s):  
D. A. Essig ◽  
S. S. Segal ◽  
T. P. White
Keyword(s):  
Protein Synthesis ◽  
Specific Activity ◽  
Muscle Protein ◽  
Peripheral Region ◽  
Core Region ◽  
Tension Development ◽  
The Core ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

We compared the structure, function, protein synthesis, and degradation of 70- to 95-mg rat soleus muscles during 120 min of incubation at 20 and 37 degrees C. At 37 degrees C, muscles were characterized by a damaged central core region and a decline of isometric tension development during incubation. Protein synthesis in the core region at 37 degrees C was depressed relative to the peripheral region. At 20 degrees C, developed tension remained constant during incubation, and synthesis rates in the core region were not different from the peripheral region. Compared with fresh muscle, ATP concentration after incubation was not affected by temperature. After equilibration of phenylalanine specific activity between extracellular and intracellular spaces (60 min at 20 degrees C; 30 min at 37 degrees C), rates of protein synthesis at 20 [0.048 nmol tyrosine (Tyr) X mg wet mass-1 X 2 h-1] and 37 degrees C (0.160 nmol Tyr X mg wet mass-1 X 2 h-1) were linear up to 180 and 120 min, respectively. Rates of protein degradation at 20 (0.076 nmol Tyr X mg wet mass-1 X 2 h-1) and 37 degrees C (0.248 nmol Tyr X mg wet mass-1 X 2 h-1) measured after 60 min were linear up to 180 and 120 min, respectively. Incubation at 20 degrees C offers an approach to study 70- to 95-mg muscles in vitro without compromising structure and function.

scholarly journals Comparison of protein synthesis and degradation in incubated and perfused muscle

1983 ◽  
Vol 212 (3) ◽  
pp. 649-653 ◽  
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.

scholarly journals Response of muscle protein turnover to insulin after acute exercise and training

1986 ◽  
Vol 240 (3) ◽  
pp. 651-657 ◽  
Author(s):  
T A Davis ◽  
I E Karl
Keyword(s):  
Protein Synthesis ◽  
Exercise Training ◽  
Protein Turnover ◽  
Acute Exercise ◽  
Muscle Protein ◽  
Muscle Protein Turnover ◽  
Exercise And Training ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

To determine whether the enhanced insulin-sensitivity of glucose metabolism in muscle after acute exercise also extends to protein metabolism, untrained and exercise-trained rats were subjected to an acute bout of exercise, and the responses of protein synthesis and degradation to insulin were measured in epitrochlearis muscles in vitro. Acute exercise of both untrained and trained rats decreased protein synthesis in muscle in the absence or presence of insulin, but protein degradation was not altered. Exercise training alone had no effect on protein synthesis or degradation in muscle in the absence or presence of insulin. Acute exercise or training alone enhanced the sensitivities of both protein synthesis and degradation to insulin, but the enhanced insulin-sensitivities from training alone were not additive to those after acute exercise. These results indicate that: a decrease in protein synthesis is the primary change in muscle protein turnover after acute exercise and is not altered by prior exercise training, and the enhanced insulin-sensitivities of metabolism of both glucose and protein after either acute exercise or training suggest post-binding receptor events.

scholarly journals Pentoxifylline improves insulin action limiting skeletal muscle catabolism after infection

1999 ◽  
Vol 163 (1) ◽  
pp. 15-24 ◽  
Author(s):  
T Vary ◽  
D Dardevet ◽  
J Grizard ◽  
L Voisin ◽  
C Buffiere ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Protein Degradation ◽  
Muscle Protein ◽  
Plasma Concentrations ◽  
Skeletal Muscle Protein ◽  
Muscle Protein Metabolism ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

We investigated the ability of pentoxifylline (PTX) to modulate protein synthesis and degradation in the presence and absence of insulin during incubation of epitrochlearis muscle, 2 or 6 days after injection of Escherichia coli. On days 2 and 6 after infection, protein synthesis was inhibited by 25%, whereas proteolysis was enhanced by 75%. Insulin (2 nM) in vitro stimulated protein synthesis in muscles from infected rats to the same extent as in controls. The ability of insulin to limit protein degradation was severely blunted 48 h after infection. On day 6 after infection, insulin inhibited proteolysis to a greater extent than on day 2. PTX suppressed the increase in plasma concentrations of tumor necrosis factor more than 600-fold after injection of bacteria, and partially prevented the inhibition of protein synthesis and stimulation of protein degradation during sepsis. Moreover, PTX administration maintained the responsiveness of protein degradation to insulin during sepsis. Thus cytokines may influence skeletal muscle protein metabolism during sepsis, both indirectly through inhibition of the effects of insulin on proteolysis, and directly on the protein synthesis and degradation machinery.

scholarly journals The effect of glutamine on protein turnover in chick skeletal muscle in vitro

1990 ◽  
Vol 265 (2) ◽  
pp. 593-598 ◽  
Author(s):  
G Wu ◽  
J R Thompson
Keyword(s):  
Protein Synthesis ◽  
Skeletal Muscles ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Plasma Concentrations ◽  
Glutamine Concentration ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

The effect of glutamine on the rates of protein synthesis and degradation was studied in isolated chick extensor digitorum communis muscles incubated in the presence of plasma concentrations of amino acids. Addition of 0.5-15 mM-glutamine increases (P less than 0.01) intracellular glutamine concentrations by 31-670%. There is a positive relationship (r = 0.975, P less than 0.01) between intracellular glutamine concentration and the rate of muscle protein synthesis measured by the incorporation of [3H]phenylalanine. The stimulating effect of 15 mM-glutamine on protein synthesis was decreased from 58 to 19% in muscles incubated in the absence of tyrosine. The rates of protein degradation, estimated from [3H]phenylalanine release from muscle proteins prelabelled in vivo, decreased (P less than 0.05) by 15-30% in the presence of 4-15 mM-glutamine when compared with muscles incubated in the presence of physiological concentrations of glutamine (0.5-1 mM). Glutamine concentrations ranging from 2 to 15 mM appear to have an overall anabolic effect on chick skeletal muscles incubated in vitro.

Effects of food deprivation on protein synthesis and degradation in rat skeletal muscles

1976 ◽  
Vol 231 (2) ◽  
pp. 441-448 ◽  
Author(s):  
JB Li ◽  
AL Goldberg
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Food Deprivation ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Rna Content ◽  
Fasted Rats ◽  
Synthesis And Degradation

The effects of food deprivation on protein turnover in rat soleus and extensor digitorum longus (EDL) were investigated. Muscles were removed from fed or fasted growing rats, and protein synthesis and breakdown were measured during incubation in vitro. Rates of synthesis and degradation were higher in the dark soleus than in the pale EDL. One day after food removal protein synthesis and RNA content in the EDL decreased. On the 2nd day of fasting, rates of protein catabolism in this muscle increased. Little or no change in synthesis and degradation occurred in the soleus. Consequently, during fasting the soleus lost much less weight than the EDL and other rat muscles. In unsupplemented buffer or in medium containing amino acids, glucose, and insulin, the muscles of fasted rats showed a lower rate of protein synthesis expressed per milligram of tissue but not per microgram of RNA. Thus the decrease in muscle RNA on fasting was responsible for the reduced synthesis observed under controlled in vitro conditions. In vivo the reduction in muscle protein synthesis on fasting results both from a lower RNA content and lower rate of synthesis per microgram of RNA. Reduced supply of glucose, insulin, and amino acids may account for the lower rate of synthesis per microgram of RNA demonstrable in vivo.

Protein metabolism in ovine primary muscle cultures derived from satellite cells – effects of selected peptide hormones and growth factors

1989 ◽  
Vol 122 (2) ◽  
pp. 565-571 ◽  
Author(s):  
J. A. Roe ◽  
J. M. M. Harper ◽  
P. J. Buttery
Keyword(s):  
Protein Synthesis ◽  
Growth Factors ◽  
Growth Factor ◽  
Satellite Cells ◽  
Specific Activity ◽  
Additive Effect ◽  
Type I ◽  
Igf I ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

ABSTRACT Methods were developed for the isolation and culture of satellite cells from adult sheep muscle. Differentiated cultures of these cells were used to investigate the effects of four hormones and growth factors on protein synthesis and degradation. Insulin was found to have no effect except at supraphysiological concentrations (100 nmol/l and 1 μmol/l) where it is probably cross-reacting with the insulin-like growth factor (IGF) type-I receptor. IGF-I was found to be anabolic at lower concentrations (1–3 nmol/l). Epidermal growth factor (EGF) had a smaller effect on protein synthesis and degradation than insulin or IGF-I. The specific activity of the muscle-specific enzyme creatine phosphokinase (CPK) was increased by treatment with EGF. When both IGF-I and EGF were present in the test media an additive effect on protein synthesis was observed. However, no additive effect of IGF-I and insulin was noted. No effects of bovine GH were seen. Journal of Endocrinology (1989) 122, 565–571

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