Sustained Modifications of Protein Metabolism in Various Tissues in a Rat Model of Long-Lasting Sepsis

1998 ◽  
Vol 94 (4) ◽  
pp. 413-423 ◽  
Author(s):  
Denis Breuillé ◽  
Maurice Arnal ◽  
Fabienne Rambourdin ◽  
Gérard Bayle ◽  
Didier Levieux ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Acute Phase ◽  
Muscle Protein ◽  
Plasma Concentrations ◽  
Chronic Phase ◽  
The Body ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Liver Protein ◽  
Skin Protein

1. Sepsis was induced in rats by an intravenous injection of live bacteria. Infected and pair-fed animals were studied before the infection, in an acute septic phase (day 2 post-infection), in a chronic septic phase (day 6) and in a late septic phase (day 10). Protein synthesis rates were measured in vivo after administration of a flooding dose of l[1-13C]valine. 2. During the acute phase, muscle protein loss associated with infection resulted from both a decrease in protein synthesis and an increase in proteolysis. During the chronic phase and the late phase, the increase of proteolysis in infected rats as compared with pair-fed animals persisted, worsening muscle atrophy. Skin protein synthesis rates were not significantly modified by infection. However, skin protein content decreased 6 and 10 days after infection, suggesting an increased proteolysis in response to sepsis. 3. Protein synthesis in liver of infected rats was twice that of pair-fed animals. Liver protein synthesis remained elevated in infected rats compared with pair-fed animals until day 10. Hypoalbuminaemia and high plasma concentrations of fibrinogen were evident at all periods studied. α2-Macroglobulin and α1-acid glycoprotein reached peak concentrations during the acute phase (concentrations increased 50 times in infected rats). On day 10, the levels of these proteins were still about 12-fold higher. 4. Protein synthesis rates were significantly increased in the digestive tract and lung of infected rats compared with pair-fed groups on days 2 and 6, but were similar in the two groups on day 10 postinfection. The fractional protein synthesis rate was increased 3-fold over the entire experimental period in the spleen. 5. The results show that sepsis stimulates protein synthesis in various tissues over a long time, and that skin, like muscle, can provide amino acids to the rest of the body.

scholarly journals MECHANISMS IN ENDOCRINOLOGY: Exogenous insulin does not increase muscle protein synthesis rate when administered systemically: a systematic review

2015 ◽  
Vol 173 (1) ◽  
pp. R25-R34 ◽  
Author(s):  
Jorn Trommelen ◽  
Bart B L Groen ◽  
Henrike M Hamer ◽  
Lisette C P G M de Groot ◽  
Luc J C van Loon
Keyword(s):  
Systematic Review ◽  
Older Adults ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Exogenous Insulin ◽  
Insulin Administration ◽  
Muscle Protein Synthesis Rate

BackgroundThough it is well appreciated that insulin plays an important role in the regulation of muscle protein metabolism, there is much discrepancy in the literature on the capacity of exogenous insulin administration to increase muscle protein synthesis ratesin vivoin humans.ObjectiveTo assess whether exogenous insulin administration increases muscle protein synthesis rates in young and older adults.DesignA systematic review of clinical trials was performed and the presence or absence of an increase in muscle protein synthesis rate was reported for each individual study arm. In a stepwise manner, multiple models were constructed that excluded study arms based on the following conditions: model 1, concurrent hyperaminoacidemia; model 2, insulin-induced hypoaminoacidemia; model 3, supraphysiological insulin concentrations; and model 4, older, more insulin resistant, subjects.ConclusionsFrom the presented data in the current systematic review, we conclude that: i) exogenous insulin and amino acid administration effectively increase muscle protein synthesis, but this effect is attributed to the hyperaminoacidemia; ii) exogenous insulin administered systemically induces hypoaminoacidemia which obviates any insulin-stimulatory effect on muscle protein synthesis; iii) exogenous insulin resulting in supraphysiological insulin levels exceeding 50 000 pmol/l may effectively augment muscle protein synthesis; iv) exogenous insulin may have a diminished effect on muscle protein synthesis in older adults due to age-related anabolic resistance; and v) exogenous insulin administered systemically does not increase muscle protein synthesis in healthy, young adults.

Pentoxifylline decreases body weight loss and muscle protein wasting characteristics of sepsis

1993 ◽  
Vol 265 (4) ◽  
pp. E660-E666 ◽  
Author(s):  
D. Breuille ◽  
M. C. Farge ◽  
F. Rose ◽  
M. Arnal ◽  
D. Attaix ◽  
...  
Keyword(s):  
Body Weight ◽  
Protein Synthesis ◽  
Acute Phase ◽  
Protein Metabolism ◽  
Muscle Wasting ◽  
Acute Phase Protein ◽  
Muscle Protein ◽  
Liver Protein ◽  
Phase Protein

Sepsis induces metabolic disorders that include loss of body weight, muscle wasting, and acute-phase protein synthesis in liver. Cytokines are generally recognized as active mediators of these disorders, and the implication of tumor necrosis factor (TNF) has been frequently discussed in the recent past. However, the identity of the active agent in alterations of protein metabolism is still controversial. To improve our understanding of the role of cytokines in mediating muscle wasting observed in sepsis, we investigated muscle and liver protein metabolism in the following three groups of rats: infected control rats (INF-C); infected rats pretreated with pentoxifylline (PTX-INF), which is a potent inhibitor of TNF secretion; and pair-fed rats for the PTX-INF group pretreated with pentoxifylline. Pentoxifylline nearly completely suppressed TNF secretion but did not influence the transient fall in rectal temperature, the decreased hematocrit, and the increased liver protein mass and synthesis observed in INF-C rats. Pentoxifylline decreased the anorexia, the loss of body weight and muscle protein observed in INF-C animals, and partially prevented the decrease in muscle protein synthesis induced by infection. The overall data indicate that pentoxifylline is an effective agent in mitigating the characteristic muscle protein wasting induced by sepsis and confirm the limited role of TNF in the mediation of the acute-phase protein synthesis. Our results suggest a probable implication of TNF in the regulation of protein balance in muscle but do not allow discarding possible implication of other mediators that would be inhibited by pentoxifylline.

Effect of Dietary Restriction on Protein Synthesis and Wound Healing after Surgery in the Rat

1995 ◽  
Vol 89 (4) ◽  
pp. 383-388 ◽  
Author(s):  
Peter W. Emery ◽  
Peter Sanderson
Keyword(s):  
Wound Healing ◽  
Protein Synthesis ◽  
Dietary Restriction ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Chronically Ill ◽  
Abdominal Muscle ◽  
Collagen Content ◽  
Synthesis Rate ◽  
Protein Synthesis Rate

1. The healing of an abdominal muscle wound after surgery is associated with a considerable increase in the rate of protein synthesis. We have investigated whether this increase in protein synthesis is affected by chronic undernutrition, and whether this causes a delay in wound healing. 2. A group of rats was fed 58% of the voluntary food intake of a matched control group. After 7 days half the rats in each group underwent abdominal surgery. Forty-eight hours later all the rats were killed and muscle protein synthesis rate was measured by the flooding dose technique. 3. In a second experiment using the same dietary regimen rats were placed in metabolic cages after surgery and killed 7 days later. In addition to measurements of muscle protein synthesis, wound breaking strength was measured with a tensiometer and collagen content was also measured at the wound site. 4. Dietary restriction caused a loss of body weight, a decrease in nitrogen balance and a deficit in muscle protein mass. It also caused a decrease in protein synthesis rate in gastrocnemius muscle and in parts of the abdominal muscle distant from the site of the wound. However, it had no effect on the rate of muscle protein synthesis at the site of the wound either 2 or 7 days after surgery. The tensile strength and the collagen content of the wound were also unaffected by food restriction. 5. It is concluded that the wound healing process is uniquely protected from the effects of moderate undernutrition such as might be experienced by a chronically ill patient.

Regulation of hepatic protein synthesis in chronic inflammation and sepsis

1992 ◽  
Vol 262 (2) ◽  
pp. C445-C452 ◽  
Author(s):  
T. C. Vary ◽  
S. R. Kimball
Keyword(s):  
Protein Synthesis ◽  
Sterile Inflammation ◽  
Chain Elongation ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Translational Efficiency ◽  
Liver Protein ◽  
Ribosomal Subunits ◽  
Hepatic Protein Synthesis

The regulation of protein synthesis was determined in livers from control, sterile inflammatory, and septic animals. Total liver protein was increased in both sterile inflammation and sepsis. The rate of protein synthesis in vivo was measured by the incorporation of [3H]phenylalanine into liver proteins in a chronic (5 day) intra-abdominal abscess model. Both sterile inflammation and sepsis increased total hepatic protein synthesis approximately twofold. Perfused liver studies demonstrated that the increased protein synthesis rate in vivo resulted from a stimulation in the synthesis of both secreted and nonsecreted proteins. The total hepatic RNA content was increased 40% only in sterile inflammation, whereas the translational efficiency was increased twofold only in sepsis. The increase in translational efficiency was accompanied by decreases in the amount of free 40S and 60S ribosomal subunits in sepsis. Rates of peptide-chain elongation in vivo were increased 40% in both sterile inflammation and sepsis. These results demonstrate that sepsis induces changes in the regulation of hepatic protein synthesis that are independent of the general inflammatory response. In sterile inflammation, the increase in protein synthesis occurs by a combination of increased capacity and translational efficiency, while in sepsis, the mechanism responsible for accelerated protein synthesis is an increased translational efficiency.

Metabolism of skin and muscle protein is regulated differently in response to nutrition

1998 ◽  
Vol 274 (3) ◽  
pp. E484-E492 ◽  
Author(s):  
Xiao-Jun Zhang ◽  
David L. Chinkes ◽  
David Doyle ◽  
Robert R. Wolfe
Keyword(s):  
Muscle Protein ◽  
Normal Skin ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Potential Contribution ◽  
Fat Emulsion ◽  
Protein Kinetics ◽  
Protein Mass ◽  
Skin Protein ◽  
Muscle Protein Metabolism

We have measured skin and muscle protein kinetics and amino acid (AA) transport in anesthetized rabbits during 1) 64-h fast, 2) AA infusion, 3) AA plus fat emulsion infusion, and 4) AA plus hyperinsulinemia.l-[ ring-13C6]phenylalanine was infused as the tracer, and the ear and hindlimb were used as arteriovenous units to reflect skin and muscle protein kinetics, respectively. Skin protein net balance was not different from zero in all groups, indicating a maintenance of protein mass. In contrast, the muscle net balance differed over a range from −1.6 ± 0.6 after fasting to 0.2 ± 0.2 μmol ⋅ 100 g−1⋅ h−1during hyperinsulinemia. In the skin, 59–66% of intracellular free phenylalanine came from proteolysis, and phenylalanine availability from proteolysis was positively correlated to the protein synthesis rate. In conclusion, normal skin maintains its constant protein mass by efficient reutilization of AAs from proteolysis. In contrast to muscle, skin protein is relatively insensitive to control by nutritional and hormonal factors. Because of the metabolic differences, when limb models are used for muscle protein metabolism, the potential contribution by limb skin should be considered.

scholarly journals Human Muscle Protein Synthesis Rates after Intake of Hydrolyzed Porcine-Derived and Cows’ Milk Whey Proteins—A Randomized Controlled Trial

Nutrients ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 989 ◽  
Author(s):  
Bendtsen ◽  
Thorning ◽  
Reitelseder ◽  
Ritz ◽  
Hansen ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
G Protein ◽  
Whey Protein ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Muscle Proteins ◽  
Mixed Meal ◽  
The Impact

Abstract: Background: Whey protein has been shown to be one of the best proteins to stimulate muscle protein synthesis rate (MPS), but other high quality proteins, e.g., animal/porcine-derived, could have similar effects. Objective: To investigate the effects of hydrolyzed porcine proteins from blood (HPB) and muscle (HPM), in comparison to hydrolyzed whey protein (HW), on MPS after intake of 15 g alone or 30 g protein as part of a mixed meal. We hypothesized that the postprandial MPS would be similar for porcine proteins and whey protein. Design: Eighteen men (mean ± SD age: 24 ± 1 year; BMI: 21.7 ± 0.4 kg/m2) participated in the randomized, double-blind, three-way cross-over study. Subjects consumed the three test products (HPB, HPM and HW) in a random order in two servings at each test day. Serving 1 consisted of a drink with 15 g protein and serving 2 of a drink with 30 g protein together with a mixed meal. A flood-primed continuous infusion of (ring-13C6) phenylalanine was performed and muscle biopsies, blood and urine samples were collected for determination of MPS, muscle free leucine, plasma amino acid concentrations and urea excretion. Results: There were no statistical differences between the MPS measured after consuming 15 g protein alone or 30 g with a mixed meal (p = 0.53) of HPB (0.048 ± 0.007 vs. 0.049 ± 0.008%/h, resp.), HPM (0.063 ± 0.011 vs. 0.062 ± 0.011 %/h, resp.) and HW (0.058 ± 0.007 vs. 0.071 ± 0.013%/h, resp.). However, the impact of protein type on MPS reached statistical tendency (HPB vs. HPM (p = 0.093) and HPB vs. HW (p = 0.067)) with no difference between HPM and HW (p = 0.88). Plasma leucine, branched-chain, essential and total amino acids were generally higher for HPB and HW than HPM (p < 0.01), which reflected their content in the proteins. Muscle-free leucine was higher for HPB than HW and HPM (p < 0.05). Conclusion: Hydrolyzed porcine proteins from blood and muscle resulted in an MPS similar to that of HW, although with a trend for porcine blood proteins to be inferior to muscle proteins and whey. Consequently, these porcine-derived muscle proteins can be used similarly to whey protein to support maintenance of skeletal muscle as part of supplements and ingredients in foods.

Inhibition of liver protein synthesis during laparoscopic surgery

1999 ◽  
Vol 277 (4) ◽  
pp. E591-E596 ◽  
Author(s):  
Hans Barle ◽  
Björn Nyberg ◽  
Stig Ramel ◽  
Pia Essén ◽  
Margaret A. McNurlan ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Laparoscopic Surgery ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Liver Protein ◽  
Early Group ◽  
Total Liver ◽  
Elective Laparoscopic Cholecystectomy ◽  
Absolute Synthesis ◽  
Late Group

Previous studies have indicated that laparoscopic surgery is associated with a decline in liver protein synthesis. In this study, the fractional synthesis rate (FSR) of total liver protein and albumin was measured in patients undergoing elective laparoscopic cholecystectomy at different times after commencing the procedure ( n = 8 + 8). Liver biopsy specimens were taken after 15 min of surgery in an “early” group and after 49 min of surgery in a “late” group. The liver FSR was higher in the early group (24.1 ± 4.7%/day) compared with the late group (19.0 ± 2.8%/day, P < 0.02). The fractional and absolute synthesis rates of albumin were similar in the two groups, 6.4 ± 1.5 vs. 6.5 ± 1.0%/day and 97 ± 19 vs. 96 ± 18 mg ⋅ kg−1⋅ day−1for the early and late groups, respectively. It is concluded that laparoscopic surgery was accompanied by a decrease in total liver protein synthesis rate, which developed rapidly during surgery. In contrast, no change in the synthesis rate of albumin was apparent during the course of surgery.

Total and net muscle protein breakdown in infection determined by amino acid effluxes

1990 ◽  
Vol 258 (5) ◽  
pp. E856-E863 ◽  
Author(s):  
J. Sjolin ◽  
H. Stjernstrom ◽  
G. Friman ◽  
J. Larsson ◽  
J. Wahren
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Urinary Excretion ◽  
Protein Degradation ◽  
Muscle Protein ◽  
Human Infection ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Skeletal Muscle Protein ◽  
Mild Disease

The present investigation was undertaken to study whether, in human infection of varying severity, peripheral 3-methylhistidine efflux and urinary excretion are associated with net protein degradation and to estimate the protein synthesis rate from the combined effluxes of 3-methylhistidine, tyrosine, and phenylalanine. Quadruplicate femoral arteriovenous differences of 3-methylhistidine, tyrosine, and phenylalanine were multiplied by leg plasma flow in 15 infected patients. Leg effluxes for 3-methylhistidine, tyrosine, and phenylalanine were -0.074 +/- 0.011, -2.57 +/- 0.43, and -3.17 +/- 0.44 mumol/min, respectively. There was a significant linear relationship (P less than 0.01) between the effluxes of tyrosine and phenylalanine and the efflux and urinary excretion of 3-methylhistidine. A significant release of tyrosine and phenylalanine was observed in patients studied at the 3-methylhistidine level seen in normal healthy subjects. It is concluded that in infection 1) there is an increased breakdown of skeletal muscle protein and a reduced rate of protein synthesis, with the latter being relatively more important in patients with mild disease; and 2) urinary 3-methylhistidine excretion is associated with net skeletal muscle protein degradation for the patient group studied.

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