Skeletal muscle degradation and nitrogen wasting in rats with chronic metabolic acidosis

1991 ◽  
Vol 80 (5) ◽  
pp. 457-462 ◽  
Author(s):  
Bryan Williams ◽  
Ellis Layward ◽  
John Walls
Keyword(s):  
Skeletal Muscle ◽  
Metabolic Acidosis ◽  
Time Course ◽  
Muscle Protein ◽  
Nitrogen Excretion ◽  
Protein Catabolism ◽  
Skeletal Muscle Protein ◽  
Body Protein ◽  
Chronic Metabolic Acidosis ◽  
Urea Production

1. Chronic metabolic acidosis is associated with impaired growth and negative nitrogen balance, suggesting that it promotes endogenous protein catabolism. 2. Skeletal muscle is the major repository of body protein and is a potential target for stimuli of protein catabolism. 3. This study in vivo examines the effects of chronic metabolic acidosis on the relationship between growth, nitrogen disposal and skeletal muscle catabolism in the rat. 4. Growth, nitrogen utilization and acquisition of body mass were significantly impaired in acidotic animals compared with pair-fed controls. 5. Total nitrogen excretion was significantly increased in acidotic rats despite decreased urea production. The time course of this response to acidosis was synchronous with that of accelerated protein catabolism in skeletal muscle. 6. It is proposed that metabolic acidosis impairs growth by stimulating skeletal muscle protein catabolism. It is suggested that this forms part of a co-ordinated multi-organ homoeostatic response to acidosis, skeletal muscle and down-regulated urea production supplying the nitrogen required for renal ammoniagenesis.

Tumor necrosis factor induces skeletal muscle protein breakdown in rats

1991 ◽  
Vol 260 (5) ◽  
pp. E727-E730 ◽  
Author(s):  
M. N. Goodman
Keyword(s):  
Skeletal Muscle ◽  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Muscle Protein ◽  
Nitrogen Excretion ◽  
Protein Breakdown ◽  
Skeletal Muscle Protein ◽  
Muscle Protein Breakdown ◽  
Necrosis Factor

The metabolic response to infection includes loss of lean tissue and increased nitrogen excretion. The loss of muscle tissue during infection results in large part from accelerated skeletal muscle protein breakdown. Recent studies suggest that macrophage-derived products secreted during infection may signal increased muscle proteolysis. To test this, in the present report the ability of interleukin (IL-1) and tumor necrosis factor (TNF) to enhance muscle proteolysis was examined. Young rats were injected intravenously with either recombinant human IL-1 or TNF. For comparison some rats were injected with bacterial endotoxin. Eight hours after each treatment, the extensor digitorum longus muscles were isolated and incubated in vitro to assess muscle proteolysis by measuring tyrosine and 3-methyl-L-histidine release by the incubated muscles. Treatment of rats with either IL-1, TNF, or endotoxin all induced fever, increased serum lactate, and reduced serum zinc levels. Despite similar metabolic changes, muscle proteolysis responded differently. As expected, endotoxin treatment enhanced muscle protein breakdown, whereas IL-1 treatment was without effect. On the other hand, TNF was effective in accelerating muscle protein breakdown. TNF addition in vitro failed to enhance muscle proteolysis by incubated muscles, suggesting that its effects may be mediated in an indirect manner; however, a direct mode of action cannot yet be ruled out. Overall, the data indicate that the acute administration of TNF can signal increased muscle proteolysis similar to that observed during infection.

Prolonged bed rest decreases skeletal muscle and whole body protein synthesis

1996 ◽  
Vol 270 (4) ◽  
pp. E627-E633 ◽  
Author(s):  
A. A. Ferrando ◽  
H. W. Lane ◽  
C. A. Stuart ◽  
J. Davis-Street ◽  
R. R. Wolfe
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Bed Rest ◽  
Whole Body ◽  
Protein Breakdown ◽  
Skeletal Muscle Protein ◽  
Model Calculations ◽  
Body Protein

We sought to determine the extent to which the loss of lean body mass and nitrogen during inactivity was due to alterations in skeletal muscle protein metabolism. Six male subjects were studied during 7 days of diet stabilization and after 14 days of stimulated microgravity (-6 degrees bed rest). Nitrogen balance became more negative (P < 0.03) during the 2nd wk of bed rest. Leg and whole body lean mass decreased after bed rest (P < 0.05). Serum cortisol, insulin, insulin-like growth factor I, and testosterone values did not change. Arteriovenous model calculations based on the infusion of L-[ring-13C6]-phenylalanine in five subjects revealed a 50% decrease in muscle protein synthesis (PS; P < 0.03). Fractional PS by tracer incorporation into muscle protein also decreased by 46% (P < 0.05). The decrease in PS was related to a corresponding decrease in the sum of intracellular amino acid appearance from protein breakdown and inward transport. Whole body protein synthesis determined by [15N]alanine ingestion on six subjects also revealed a 14% decrease (P < 0.01). Neither model-derived nor whole body values for protein breakdown change significantly. These results indicate that the loss of body protein with inactivity is predominantly due to a decrease in muscle PS and that this decrease is reflected in both whole body and skeletal muscle measures.

scholarly journals Growth Hormone and Insulin Reverse Net Whole Body and Skeletal Muscle Protein Catabolism in Cancer Patients

1992 ◽  
Vol 216 (3) ◽  
pp. 280-290 ◽  
Author(s):  
RONALD F. WOLF ◽  
DAVID B. PEARLSTONE ◽  
ELLIOT NEWMAN ◽  
MARTIN J. HESLIN ◽  
AMNON GONENNE ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Growth Hormone ◽  
Cancer Patients ◽  
Muscle Protein ◽  
Whole Body ◽  
Protein Catabolism ◽  
Skeletal Muscle Protein

Lactation induces upregulation of the ubiquitin-mediated proteolytic pathway in skeletal muscle of dairy cows but does not alter hepatic expression

2009 ◽  
Vol 89 (3) ◽  
pp. 309-313 ◽  
Author(s):  
S L Greenwood ◽  
T C Wright ◽  
N G Purdie ◽  
J Doelman ◽  
J P Cant ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Dairy Cows ◽  
Mrna Expression ◽  
Muscle Protein ◽  
Post Partum ◽  
Skeletal Muscle Protein ◽  
Protein Loss ◽  
Body Protein ◽  
Hepatic Expression ◽  
Proteolytic Pathway

The current study investigates regulation of mRNA expression of components of ubiquitin-mediated proteolysis in transition dairy cows. Longissimus dorsi muscle (exp. 1) and liver (exp. 2) biopsies were collected from Holstein dairy cows at 27 and 16 d pre-partum, respectively, and 3 and 10 d post-partum, respectively. Regulation of C8, E2, and ubiquitin mRNA expression was determined. Upregulation of skeletal muscle C8 (P = 0.09) and ubiquitin (P = 0.004) mRNA expression occurred post-partum compared with pre-partum. No regulation of hepatic mRNA expression was observed. In conclusion, ubiquitin-mediated proteolysis may contribute to skeletal muscle protein degradation during the periparturient period, and could provide a potential mechanism for attenuation of body protein loss at the onset of lactation.Key words: Lactation, ubiquitin-mediated proteolytic pathway, muscle (skeletal), liver

scholarly journals Skeletal muscle protein catabolism, protein anabolism, and myogenesis after various types of insults

2020 ◽  
Vol 54 (3) ◽  
pp. 139-142
Author(s):  
Yuko Ono ◽  
Masafumi Saito ◽  
Yoshihisa Fujinami ◽  
Shigeaki Inoue ◽  
Joji Kotani
Keyword(s):  
Skeletal Muscle ◽  
Muscle Protein ◽  
Protein Catabolism ◽  
Skeletal Muscle Protein

scholarly journals The inhibition of phosphodiesterase 4 reduces skeletal muscle protein catabolism by suppressing autophagy/lysosomal and proteasomal pathways and atrophy‐specific gene transcription

2010 ◽  
Vol 24 (S1) ◽  
Author(s):  
Eduardo Carvalho Lira ◽  
Lucas Tabajara Parreiras‐e‐Silva ◽  
Neusa Maria Zanon ◽  
Cláudio Miguel Costa Neto ◽  
Ísis Carmo Kettelhut ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Gene Transcription ◽  
Muscle Protein ◽  
Specific Gene ◽  
Protein Catabolism ◽  
Skeletal Muscle Protein ◽  
Phosphodiesterase 4

Effect of glycogen availability on human skeletal muscle protein turnover during exercise and recovery

2010 ◽  
Vol 109 (2) ◽  
pp. 431-438 ◽  
Author(s):  
Krista R. Howarth ◽  
Stuart M. Phillips ◽  
Maureen J. MacDonald ◽  
Douglas Richards ◽  
Natalie A. Moreau ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Whole Body ◽  
Skeletal Muscle Protein ◽  
Protein Balance ◽  
Body Protein ◽  
Muscle Protein Turnover ◽  
Net Protein

We examined the effect of carbohydrate (CHO) availability on whole body and skeletal muscle protein utilization at rest, during exercise, and during recovery in humans. Six men cycled at ∼75% peak O2 uptake (V̇o2peak) to exhaustion to reduce body CHO stores and then consumed either a high-CHO (H-CHO; 71 ± 3% CHO) or low-CHO (L-CHO; 11 ± 1% CHO) diet for 2 days before the trial in random order. After each dietary intervention, subjects received a primed constant infusion of [1-13C]leucine and l-[ring-2H5]phenylalanine for measurements of the whole body net protein balance and skeletal muscle protein turnover. Muscle, breath, and arterial and venous blood samples were obtained at rest, during 2 h of two-legged kicking exercise at ∼45% of kicking V̇o2peak, and during 1 h of recovery. Biopsy samples confirmed that the muscle glycogen concentration was lower in the L-CHO group versus the H-CHO group at rest, after exercise, and after recovery. The net leg protein balance was decreased in the L-CHO group compared with at rest and compared with the H-CHO condition, which was primarily due to an increase in protein degradation (area under the curve of the phenylalanine rate of appearance: 1,331 ± 162 μmol in the L-CHO group vs. 786 ± 51 μmol in the H-CHO group, P < 0.05) but also due to a decrease in protein synthesis late in exercise. There were no changes during exercise in the rate of appearance compared with rest in the H-CHO group. Whole body leucine oxidation increased above rest in the L-CHO group only and was higher than in the H-CHO group. The whole body net protein balance was reduced in the L-CHO group, largely due to a decrease in whole body protein synthesis. These data extend previous findings by others and demonstrate, using contemporary stable isotope methodology, that CHO availability influences the rates of skeletal muscle and whole body protein synthesis, degradation, and net balance during prolonged exercise in humans.

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