Assessment in vitro and in vivo of muscle degradation in chronic skeletal muscle myopathy of alcoholism

1985 ◽  
Vol 68 (6) ◽  
pp. 693-700 ◽  
Author(s):  
Finbarr C. Martin ◽  
Timothy J. Peters
Keyword(s):  
Skeletal Muscle ◽  
Muscle Wasting ◽  
Muscle Protein ◽  
Protein Breakdown ◽  
Turnover Rates ◽  
Alcoholic Myopathy ◽  
Biochemical Journal ◽  
Muscle Breakdown

1. Muscle protein breakdown in vivo has been studied by measurements of urinary 3-methylhistidine/creatinine ratios. No differences were found between control subjects and chronic alcoholics either with or without proximal muscle wasting or cirrhosis. 2. Calculation of muscle turnover rates, with the correction of Afting et al. (1981, Biochemical Journal, 200, 449-452) for non-skeletal muscle contributions of 3-methylhistidine and creatinine, showed lower values for alcoholics compared with controls. 3. Tissue activities of a neutral protease, assayed by a novel, rapid and sensitive fluorimetric method, were similar in patients and controls. The activity did not vary with severity of atrophy or the presence of cirrhosis. 4. No evidence was therefore obtained to suggest that alcoholic myopathy is due to increased muscle breakdown.

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.

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 Effects of potassium deficiency on growth and protein synthesis in skeletal muscle and the heart of rats

1989 ◽  
Vol 62 (2) ◽  
pp. 269-284 ◽  
Author(s):  
Inge Dôrup ◽  
Torben Clausen
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Control Level ◽  
Inhibitory Effect ◽  
Potassium Deficiency ◽  
Skeletal Muscle Protein ◽  
K Deficiency

The effects of potassium deficiency on growth, K content and protein synthesis have been compared in 4–13-week-old rats. When maintained on K-deficient fodder (1 mmol/kg) rats ceased to grow within a few days, and the incorporation of [3H]leucine into skeletal muscle protein in vivo was reduced by 28–38%. Pair-feeding experiments showed that this inhibition was not due to reduced energy intake. Following 14 d on K-deficient fodder, there was a further reduction (39–56 %) in the incorporation of [3H]leucine into skeletal muscle protein, whereas the incorporation into plasma, heart and liver proteins was not affected. The accumulation of the non-metabolized amino acid α-aminoisobutyric acid in the heart and skeletal muscles was not reduced. The inhibitory effect of K deficiency on 3H-labelling of muscle protein was seen following intraperitoneal (10–240 min) as well as intravenous (10 min) injection of [3H]leucine. In addition, the incorporation of [3H]phenylalanine into skeletal muscle protein was reduced in K-depleted animals. Following acute K repletion in vivo leading to complete normalization of muscle K content, the incorporation of [3H]leucine into muscle protein showed no increase within 2 h, but reached 76 and 104% of the control level within 24 and 72 h respectively. This was associated with a rapid initial weight gain, but normal body-weight was not reached until after 7 weeks of K repletion. Following 7 d on K-deficient fodder the inhibition of growth and protein synthesis was closely correlated with the K content of the fodder (1–40 mmol/kg) and significant already at modest reductions in muscle K content. In vitro experiments with soleus muscle showed a linear relationship between the incorporation of [3H]leucine into muscle protein and K content, but the sensitivity to cellular K deficiency induced in vitro was much less pronounced than that induced in vivo. Thus, in soleus and extensor digitorum longus (EDL) muscles prepared from K-deficient rats, the incorporation of [3H]leucine was reduced by 30 and 47 % respectively. This defect was completely restored by 24 h K repletion in vivo. It is concluded that in the intact organism protein synthesis and growth are very sensitive to dietary K deficiency and that this can only partly be accounted for by the reduction in cellular K content per se. The observations emphasize the need for adequate K supplies to ensure optimum utilization of food elements for protein synthesis and growth.

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.

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 PL - 033 A translational model of muscle protein synthetic bioactivity in vitro, ex vivo and in vivo

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Brian Carson ◽  
Robert Davies ◽  
Joseph Bass ◽  
Catherine Norton ◽  
Bijal Patel ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stable Isotope ◽  
Resistance Exercise ◽  
Ex Vivo ◽  
Muscle Protein ◽  
Muscle Growth ◽  
Translational Model ◽  
Nutrient Feeding

Objective The aim of this research was the development and validation of a translational model for the evaluation of exercise and nutrient stimulated muscle protein synthesis (MPS). To achieve this overall aim, three primary objectives had to be realised: (i) Development of an in vitro skeletal muscle cell bioassay to measure muscle growth and MPS; (ii) Development of an ex vivo model to evaluate the humoral effect on MPS in response to nutrient feeding and exercise; (iii) Use of a stable isotope technique to evaluate MPS in response to nutrient feeding and exercise in vivo. Methods To develop a novel in vitro skeletal muscle cell bioassay to measure muscle growth and MPS, C2C12 myoblasts were proliferated and subsequently differentiated to myotubes over 8 days in DMEM (2% HS). Changes in cell behavior and adhesion properties were monitored by measuring impedance via interdigitated microelectrodes using the xCELLigence system. MPS was measured by puromycin incorporation using the SUnSET technique, intracellular signalling measured by western blot, and myotube thickness by microscopy. To demonstrate the capability to monitor nutrient regulation of muscle growth, media was conditioned with a known potent regulator of MPS (leucine) in a dose response experiment (0.20 - 2.0 mM). To establish the ability of the bioassay to measure the humoral effect of MPS in response to feeding and exercise, media was conditioned by ex vivo human serum from fasted, rested, fed (protein and isonitrogenous non-essential amino acid (NEAA) control)  and post-exercise conditions. To evaluate MPS in response to nutrient feeding and exercise in vivo, acute MPS (5 h) was assessed by measuring stable isotope deuterium oxide (D2O) incorporation into m. vastus lateralis skeletal muscle following consumption of either a Whey Protein (WP) or an isonitrogenous NEAA control combined with resistance exercise in resistance trained males. Results In vitro experiments observed a dose-response effect with a 32 % increase in cell index and a 27 % increase in cell thickness after 2 h in the presence of 2.0 mM leucine when compared with control myotubes. Ex vivo serum following ingestion of NEAA had no effect on protein signalling or MPS whereas WP fed serum significantly increased mTOR, P70S6K and 4E-BP1 phosphorylation (p<0.01, p<0.05) compared to fasted serum. Furthermore, the effect of WP fed serum on protein signalling and MPS was significantly increased (p<0.01, p<0.05) compared to NEAA fed serum.  Ex vivo human serum following resistance exercise was also increased MPS (29 %) and phosphorylation of mTOR (6 %), p70S6K (12 %) and 4EBP1 (7 %), compared with resting serum. These ex vivo/in vitro findings translated to the in vivo model as myofibrillar fractional synthetic rates (myoFSR) (Basal 0.068±0.002%h-1 vs. WP 0.084±0.006 %h-1, p=0.033) and absolute synthetic rates (ASR) (Basal 10.34±1.01 vs. WP 13.18±0.71 g.day-1, p=0.026) were increased from basal levels only when resistance exercise was combined with WP ingestion and not the NEAA control (NEAA MPS 0.072±0.004%h-1, NEAA ASR 10.23±0.80 g.day-1).  Thus, ingestion of WP in combination with resistance training augments acute MPS responses in resistance trained young men. Conclusions We have developed a translational model of muscle protein synthetic bioactivity using in vitro, ex vivo and in vivo methodologies. We have shown that we can impact MPS in vitro using ex vivo human serum to condition media, that MPS in vitro is differentially regulated by ex vivo serum containing bioactive WP compared to a non-bioactive NEAA control, and that this tranlates for resistance exercise combined with WP in humans when MyoFSR is measured using stable isotope technology.  These experiments demonstrate that ex vivo/in vitro experiments translate to the in vivo model and these methods can be used to inform both exercise and nutrient human interventions. 

Skeletal muscle, liver and wool protein synthesis by sheep infected by the nematode Trichostrongylus colubriformis

1975 ◽  
Vol 26 (6) ◽  
pp. 1063
Author(s):  
LEA Symons ◽  
WO Jones
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Liver Protein ◽  
Trichostrongylus Colubriformis ◽  
Intestinal Nematode ◽  
Skeletal Muscle Proteins

Incorporation of radioisotopically labelled L-leucine into skeletal muscle proteins was measured in vivo and in vitro, and into liver proteins in vivo in three groups of sheep: (1) infected by Trichostrongylus colubriformis, (2) uninfected, pair-fed with the infected animals, (3) uninfected, fed ad lib. Incorporation of [14C]L-leucine by an homogenate of wool follicles from infected and uninfected sheep was also measured. Incorporation of leucine by muscle, and hence muscle protein synthesis, was equally depressed in the anorexic infected sheep losing weight, and in pair-fed animals, whether measured in vivo or in vitro, or expressed in terms of either RNA or DNA. Incorporation into protein was elevated equally in vivo in the livers of the infected and pair-fed sheep when expressed in terms of content of tissue nitrogen, but not in terms of cither nucleic acid. Incorporation by the wool follicular homogenate was appreciably depressed by the infection and is consistent with the poor wool growth in nematode infections. These results show that the same depression of skeletal muscle and, possibly, elevation of liver protein synthesis occur in a ruminant as were reported earlier for laboratory monogastric animals with intestinal nematode infections. Pair-feeding uninfected animals in both this and the earlier experiments emphasized the importance of anorexia as a major cause of these effects on protein synthesis. The importance of these effects upon production is discussed briefly.

Effect of heart failure on the regulation of skeletal muscle protein synthesis, breakdown, and apoptosis

2003 ◽  
Vol 284 (5) ◽  
pp. E1001-E1008 ◽  
Author(s):  
Rebecca Persinger ◽  
Yvonne Janssen-Heininger ◽  
Simon S. Wing ◽  
Dwight E. Matthews ◽  
Martin M. LeWinter ◽  
...  
Keyword(s):  
Heart Failure ◽  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Food Intake ◽  
Muscle Wasting ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Protein Breakdown ◽  
Skeletal Muscle Protein ◽  
Skeletal Muscle Protein Synthesis

Heart failure is often characterized by skeletal muscle atrophy. The mechanisms underlying muscle wasting, however, are not fully understood. We studied 30 Dahl salt-sensitive rats (10 male, 20 female) fed either a high-salt (HS; n = 15) or a low-salt (LS; n = 15) diet. This strain develops cardiac hypertrophy and failure when fed a HS diet. LS controls were matched to HS rats for gender and duration of diet. Body mass, food intake, and muscle mass and composition were measured. Skeletal muscle protein synthesis was measured by isotope dilution. An additional group of 27 rats (HS, n = 16; LS; n = 11) were assessed for expression of genes regulating protein breakdown and apoptosis. Gastrocnemius and plantaris muscles weighed less (16 and 22%, respectively) in HS than in LS rats ( P < 0.01). No differences in soleus or tibialis anterior weights were found. Differences in muscle mass were abolished after data were expressed relative to body size, because HS rats tended ( P = 0.094) to weigh less. Lower body mass in HS rats was related to a 16% reduction ( P < 0.01) in food intake. No differences in muscle protein or DNA content, the protein-to-DNA ratio, or muscle protein synthesis were found. Finally, no differences in skeletal muscle gene expression were found to suggest increased protein breakdown or apoptosis in HS rats. Our results suggest that muscle wasting in this model of heart failure is not associated with alterations in skeletal muscle metabolism. Instead, muscle atrophy was related to reduced body weight secondary to decreased food intake. These findings argue against the notion that heart failure is characterized by a skeletal muscle myopathy that predisposes to atrophy.

Corrigendum - Skeletal muscle, liver and wool protein synthesis by sheep infected by the nematode Trichostrongylus colubriformis

1975 ◽  
Vol 26 (6) ◽  
pp. 1063
Author(s):  
LEA Symons ◽  
WO Jones
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Liver Protein ◽  
Trichostrongylus Colubriformis ◽  
Intestinal Nematode ◽  
Skeletal Muscle Proteins

Incorporation of radioisotopically labelled L-leucine into skeletal muscle proteins was measured in vivo and in vitro, and into liver proteins in vivo in three groups of sheep: (1) infected by Trichostrongylus colubriformis, (2) uninfected, pair-fed with the infected animals, (3) uninfected, fed ad lib. Incorporation of [14C]L-leucine by an homogenate of wool follicles from infected and uninfected sheep was also measured. Incorporation of leucine by muscle, and hence muscle protein synthesis, was equally depressed in the anorexic infected sheep losing weight, and in pair-fed animals, whether measured in vivo or in vitro, or expressed in terms of either RNA or DNA. Incorporation into protein was elevated equally in vivo in the livers of the infected and pair-fed sheep when expressed in terms of content of tissue nitrogen, but not in terms of cither nucleic acid. Incorporation by the wool follicular homogenate was appreciably depressed by the infection and is consistent with the poor wool growth in nematode infections. These results show that the same depression of skeletal muscle and, possibly, elevation of liver protein synthesis occur in a ruminant as were reported earlier for laboratory monogastric animals with intestinal nematode infections. Pair-feeding uninfected animals in both this and the earlier experiments emphasized the importance of anorexia as a major cause of these effects on protein synthesis. The importance of these effects upon production is discussed briefly.

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