Muscle Protein Synthesis and Degradation in Chicks Adapted to Intermittent Feeding: in vitro Studies

1987 ◽  
Vol 31 (6) ◽  
pp. 362-366 ◽  
Author(s):  
Y. Pinchasov ◽  
I. Nir ◽  
Zafrira Nitsan
1983 ◽  
Vol 212 (3) ◽  
pp. 649-653 ◽  
Author(s):  
A S Clark ◽  
W E Mitch

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.


1990 ◽  
Vol 265 (2) ◽  
pp. 593-598 ◽  
Author(s):  
G Wu ◽  
J R Thompson

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.


1976 ◽  
Vol 231 (2) ◽  
pp. 441-448 ◽  
Author(s):  
JB Li ◽  
AL Goldberg

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.


1994 ◽  
Vol 45 (5) ◽  
pp. 1432-1439 ◽  
Author(s):  
Giacomo Garibotto ◽  
Rodolfo Russo ◽  
Antonella Sofia ◽  
Maria Rita Sala ◽  
Cristina Robaudo ◽  
...  

1986 ◽  
Vol 240 (3) ◽  
pp. 651-657 ◽  
Author(s):  
T A Davis ◽  
I E Karl

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.


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