scholarly journals The retention and metabolism of Nτ-methylhistidine by cockerels: implications for the measurement of muscle protein breakdown determined from the excretion of Nτmethylhistidine in excreta

1987 ◽  
Vol 57 (3) ◽  
pp. 467-478 ◽  
Author(s):  
C. I. Harris ◽  
G. Milne ◽  
Ruth McDiarmid
Keyword(s):  
Skeletal Muscle ◽  
Subcutaneous Injection ◽  
Muscle Protein ◽  
Protein Breakdown ◽  
Reliable Index ◽  
Muscle Protein Breakdown ◽  
Thigh Muscles ◽  
Daily Excretion ◽  
Total Pool

1. Excreta were collected for four consecutive days from 4- to 18-week-old cockerels following subcutaneous injection of Nτ-[14CH3]methylhistidine.2. The recoveries of radioactivity in excreta were incomplete and progressively decreased with increasing age.3. Most of the radioactivity not recovered in excreta after 4 d was found in skeletal muscle where > 55% of the radioactivity present was in the Nτ-methylhistidine-containing dipeptide, balenine.4. This peptide appeared to be relatively stable so that most of the labelled Nτ-methylhistidine incorporated was not released during the period of the recovery measurements.5. The total pool of non-protein bound Nτ-methylhistidine (free Nτ-methylhistidine+balenine) in pectoral and mixed thigh muscles increased with age and relative to the daily excretion of Nτ-methylhistidine. At 18 weeks the pool was 3.3 times the daily excretion of Nτ-methylhistidine.6. These observations account for the decreasing recoveries of radioactivity in excreta described previously, due to progressive dilution of labelled Nτ-methylhistidine in an expanding pool of non-protein-bound Nτ-methylhistidine, part of which was relatively stable.7. It is concluded that excretion of Nτ-methylhistidine by 4- to 18-week-old cockerels cannot be used as a reliable index of muscle protein breakdown in vivo.

scholarly journals The urinary excretion of Nτ-methyl histidine in sheep: an invalid index of muscle protein breakdown

1980 ◽  
Vol 44 (2) ◽  
pp. 129-140 ◽  
Author(s):  
C. I. Harris ◽  
G. Milne
Keyword(s):  
Urinary Excretion ◽  
Muscle Tissue ◽  
Intravenous Administration ◽  
Muscle Protein ◽  
Protein Breakdown ◽  
Reliable Index ◽  
Urinary Recovery ◽  
Main Determinant ◽  
Muscle Protein Breakdown

1. The validity of the urinary excretion of Nτ-methyl histidine (Nτ-MH) in sheep as a measure of the breakdown of muscle protein in vivo was assessed from the urinary recovery of radioactivity following the intravenous administration of Nτ-[14CH3]methylhistidine.2. Recoveries of radioactivity in urine from animals of 4 weeks to 7 years of age were incomplete in 7 d but progressively increased with the age of the animal, becoming almost quantitative (90%) in older animals after recovery for 3 weeks.3. The incomplete urinary recoveries were not due to partial excretion of Nτ-MH in faeces or its oxidation and elimination in expired gases but were related to the presence in muscle of a pool of non-protein-bound Nτ-MH which was several times larger than the expected daily urinary excretion.4. This pool in newly accreted muscle tissue was maintained by retention of some of the Nτ-MH released by breakdown of muscle protein. Hence, only a proportion of the Nτ-MH released from protein breakdown was available for excretion. This proportion increased with the age of the animal and was probably the main determinant of the improved recoveries of radioactivity obtained in urine from older animals.5. The non-protein-bound Nτ-MH in muscle consisted of free Nτ-MH and a dipeptide containing Nτ-MH, the latter comprising on average approximately 82% of the total non-protein-bound Nτ-MH in muscle. This proportion did not change appreciably with the age of the animal.6. The dipeptide appeared to be synthesized in muscle from free Nτ-MH and was not a terminal product of protein breakdown.7. The results show that urinary excretion of Nτ-MH is not a reliable index of muscle protein breakdown in sheep.

Role of Interleukin-6 in Skeletal Muscle Protein Breakdown and Cathepsin Activity in vivo

1996 ◽  
Vol 28 (5) ◽  
pp. 361-366 ◽  
Author(s):  
J. Fujita ◽  
T. Tsujinaka ◽  
C. Ebisui ◽  
M. Yano ◽  
H. Shiozaki ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Interleukin 6 ◽  
Muscle Protein ◽  
Protein Breakdown ◽  
Skeletal Muscle Protein ◽  
Muscle Protein Breakdown ◽  
Cathepsin Activity

scholarly journals Prostaglandin E2 does not regulate total or myofibrillar protein breakdown in incubated skeletal muscle from normal or septic rats

1990 ◽  
Vol 270 (1) ◽  
pp. 45-50 ◽  
Author(s):  
P O Hasselgren ◽  
O Zamir ◽  
J H James ◽  
J E Fischer
Keyword(s):  
Skeletal Muscle ◽  
Arachidonic Acid ◽  
Prostaglandin E2 ◽  
Plasma Levels ◽  
Muscle Protein ◽  
Myofibrillar Protein ◽  
Protein Breakdown ◽  
Muscle Protein Breakdown

The role of prostaglandins in the regulation of muscle protein breakdown is controversial. We examined the influence of arachidonic acid (5 microM), prostaglandin E2 (PGE2) (2.8 microM) and the prostaglandin-synthesis inhibitor indomethacin (3 microM) on total and myofibrillar protein breakdown in rat extensor digitorum longus and soleus muscles incubated under different conditions in vitro. In other experiments, the effects of indomethacin, administered in vivo to septic rats (3 mg/kg, injected subcutaneously twice after induction of sepsis by caecal ligation and puncture) on plasma levels and muscle release of PGE2 and on total and myofibrillar protein breakdown rates were determined. Total and myofibrillar proteolysis was assessed by measuring production by incubated muscles of tyrosine and 3-methylhistidine respectively. Arachidonic acid or PGE2 added during incubation of muscles from normal rats did not affect total or myofibrillar protein degradation under a variety of different conditions in vitro. Indomethacin inhibited muscle PGE2 production by incubated muscles from septic rats, but did not lower proteolytic rates. Administration in vivo of indomethacin did not affect total or myofibrillar muscle protein breakdown, despite effective plasma levels of indomethacin with decreased plasma PGE2 levels and inhibition of muscle PGE2 release. The present results suggest that protein breakdown in skeletal muscle of normal or septic rats is not regulated by PGE2 or other prostaglandins.

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.

scholarly journals Amino acid infusion attenuates skeletal muscle protein breakdown in children with severe burns

2013 ◽  
Vol 27 (S1) ◽  
Author(s):  
Craig Porter ◽  
Matthew Cotter ◽  
David N Herndon ◽  
Labros S Sidossis ◽  
Elisabet Børsheim
Keyword(s):  
Skeletal Muscle ◽  
Amino Acid ◽  
Muscle Protein ◽  
Protein Breakdown ◽  
Skeletal Muscle Protein ◽  
Acid Infusion ◽  
Amino Acid Infusion ◽  
Muscle Protein Breakdown ◽  
Severe Burns
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