scholarly journals Comparison of the [2H5]Phenylalanine Model with the [1-13C]Leucine Method to Determine Whole Body Protein Synthesis and Degradation in Sheep Fed at Two Levels

2007 ◽  
Vol 20 (10) ◽  
pp. 1517-1524 ◽  
Author(s):  
M. Al-Mamun ◽  
C. Ito ◽  
A. Sato ◽  
T. Fujita ◽  
H. Sano
Keyword(s):  
Protein Synthesis ◽  
Whole Body ◽  
Body Protein ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Human protein metabolism: its measurement and regulation

2002 ◽  
Vol 283 (6) ◽  
pp. E1105-E1112 ◽  
Author(s):  
Zhenqi Liu ◽  
Eugene J. Barrett
Keyword(s):  
Protein Synthesis ◽  
Whole Body ◽  
Body Protein ◽  
Architectural Support ◽  
Protein Mass ◽  
Protein Pool ◽  
Tracer Kinetic ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

The body's protein mass not only provides architectural support for cells but also serves vital roles in maintaining their function and survival. The whole body protein pool, as well as that of individual tissues, is determined by the balance between the processes of protein synthesis and degradation. These in turn are regulated by interactions among hormonal, nutritional, neural, inflammatory, and other influences. Prolonged changes in either the synthetic or degradative processes (or both) that cause protein wasting increase morbidity and mortality. The application of tracer kinetic methods, combined with measurements of the activity of components of the cellular signaling pathways involved in protein synthesis and degradation, affords new insights into the regulation of both protein synthesis and breakdown in vivo. These insights, including those from studies of insulin, insulin-like growth factor I, growth hormone, and amino acid-mediated regulation of muscle and whole body protein turnover, provide opportunities to develop and test therapeutic approaches with promise to minimize or prevent these adverse health consequences.

scholarly journals Contribution of whole-body protein synthesis to basal metabolism in layer and broiler chickens

1987 ◽  
Vol 57 (2) ◽  
pp. 269-277 ◽  
Author(s):  
T. Muramatsu ◽  
Y. Aoyagi ◽  
J. Okumura ◽  
I. Tasaki
Keyword(s):  
Protein Synthesis ◽  
Broiler Chickens ◽  
Whole Body ◽  
Synthesis Rate ◽  
Body Protein ◽  
Fractional Synthesis Rate ◽  
Degradation Rates ◽  
Fractional Synthesis ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

1. The effect of starvation on whole-body protein synthesis and on the contribution of protein synthesis to basal metabolic rate was investigated in young chickens (Expt 1). Strain differences between layer and broiler chickens in whole-body protein synthesis and degradation rates were examined when the birds were starved (Expt 2).2. In Expt 1, 15-d-old White Leghorn male chickens were used, while in Expt 2 Hubbard (broiler) and White Leghorn (layer) male chickens at 14 d of age were used. They were starved for 4 d, and heat production was determined by carcass analysis after 2 and 4 d of starvation. Whole-body protein synthesis rates were measured on 0, 2 and 4 d of starvation (Expt 1), and on 0 and 4 d of starvation (Expt 2).3. The results showed that starving reduced whole-body protein synthesis in terms of fractional synthesis rate and the amount synthesized. Whole-body protein degradation was increased by starvation both in terms of fractional synthesis rate and the amount degraded on a per kg body-weight basis.4. Reduced fractional synthesis rate of protein in the whole body was accounted for by reductions in both protein synthesis per unit RNA and RNA:protein ratio.5. In the fed state, whole-body protein synthesis and degradation rates, whether expressed as fractional rates or amounts per unit body-weight, tended to be higher in layer than in broiler chickens. In the starved state, the difference in the rate of protein synthesis between the two strains virtually disappeared, while the degradation rates were higher in layer than in broiler birds.6. Based on the assumed value of 3.56 kJ/g protein synthesized (Waterlow et al. 1978), the heat associated with whole-body protein synthesis in the starved state was calculated to range from 14 to 17% of the basal metabolic rate with no strain difference between layer and broiler chickens.

scholarly journals Effect of insulin on hind-limb and whole-body leucine and protein metabolism in fed and fasted lambs

1987 ◽  
Vol 58 (3) ◽  
pp. 437-452 ◽  
Author(s):  
V. H. Oddy ◽  
D. B. Lindsay ◽  
P. J. Barker ◽  
A. J. Northrop
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Hind Limb ◽  
Whole Body ◽  
Limb Muscle ◽  
Body Protein ◽  
Leucine Metabolism ◽  
Hind Limb Muscle ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

1. A combination of isotope-dilution and arterio-venous difference techniques was used to determine rates of leucine metabolism and protein synthesis and degradation in a hind-limb preparation (predominantly muscle) and the whole body of eight lambs fed on milk to appetite and eight lambs fasted from 24 to 48 h.2. Compared with fed lambs, fasted lambs showed decreased rates of protein synthesis in both whole body and hind-limb, and in hind-limb muscle, elevated rates of protein degradation.3. The effects of two rates of insulin infusion on whole-body and hind-limb-muscle leucine metabolism, and in turn on protein metabolism, were determined. Insulin had no significant effect on leucine flux or oxidation (and hence protein synthesis and degradation) in whole-body or hind-limb muscle of fed lambs. In fasted lambs insulin progressively reduced arterial leucine concentration and whole-body leucine flux and oxidation, indicating a reduction in both protein synthesis and degradation. Insulin reduced the rate of leucine efflux from hind-limb muscle, which was followed by a reduction in leucine uptake. Insulin increased hind-limb-muscle glucose uptake in both fed and fasted lambs.4. On the basis that hind-limb muscle was representative of skeletal muscle in general, we estimated that muscle accounted for the same percentage (about 27) of whole-body protein synthesis in both fed and fasted lambs. This percentage was unaffected by infusion of insulin, although the absolute rates differed in fed and fasted lambs.

Influence of the β-adrenergic agonist cimaterol on body composition and whole body synthesis and degradation of protein in growing lambs

1992 ◽  
Vol 72 (3) ◽  
pp. 569-587 ◽  
Author(s):  
W. R. Caine ◽  
G. W. Mathison
Keyword(s):  
Body Composition ◽  
Protein Synthesis ◽  
Protein Turnover ◽  
Whole Body ◽  
Body Protein ◽  
Feeding Level ◽  
Intake Level ◽  
Psoas Major ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

A study was undertaken to determine the effect of dietary cimaterol at low (1.1 × maintenance (M)) followed by high (2.2 × M) feed intake on body composition and protein metabolism in growing lambs fed alfalfa pellets. Control (n = 5), cimaterol I (n = 5) and cimaterol II (n = 4) lambs received rations containing cimaterol at 0, 10.9 and 0 mg kg−1 of dietary dry matter (DM) at 1.1 × M and 0, 10.9 and 10.9 mg kg−1 DM at 2.2 × M intake, respectively. On day 22 at each feeding level, whole-body protein turnover was determined as estimated from 6-h continuous infusions of 1-[14C]-leucine. Longissimus dorsi areas (P = 0.03) and the weights of psoas major, gastrocnemius (P < 0.01) and semitendinosus (P = 0.06) muscles were increased in lambs fed cimaterol throughout the experiment. There was an increase in leucine irreversible loss (P = 0.006), whole body protein synthesis (P = 0.004) and accretion (P = 0.001) at the high compared to low intake. At the low intake, protein accretion was increased (P < 0.1) from 63 g d−1 in control lambs to 94 g d−1 in cimaterol-treated lambs. No difference could be detected in whole-body protein accretion in the lambs at the high feeding level. It was concluded that cimaterol-fed lambs had higher accretion of protein in muscles than control lambs and that increases in protein accretion due to cimaterol could be detected by the radioleucine method at the low-intake level but not at the high-intake level. Large differences in estimates for protein accretion obtained from leucine metabolism, nitrogen balance and liveweight gain data suggest that refinements in techniques for estimating whole-body protein synthesis and degradation are needed. Key words: Cimaterol, lambs, protein turnover, leucine, intake, amino acids

Responses of whole body protein synthesis and degradation to plantain herb in sheep exposed to heat

2008 ◽  
Vol 62 (3) ◽  
pp. 219-229 ◽  
Author(s):  
Mohammad Al-Mamun ◽  
Yuki Hanai ◽  
Chizuru Tanaka ◽  
Yoshifumi Tamura ◽  
Hiroaki Sano
Keyword(s):  
Protein Synthesis ◽  
Whole Body ◽  
Body Protein ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Mechanisms of adaptation to proteinuria in adriamycin nephrosis

1993 ◽  
Vol 265 (2) ◽  
pp. F257-F263 ◽  
Author(s):  
E. J. Choi ◽  
R. C. May ◽  
J. Bailey ◽  
T. Masud ◽  
A. Dixon ◽  
...  
Keyword(s):  
Normal Growth ◽  
Whole Body ◽  
Acid Oxidation ◽  
Body Protein ◽  
Mechanisms Of Adaptation ◽  
Protein Conservation ◽  
And Control ◽  
The Impact ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

To evaluate the impact of urinary protein losses on whole body protein turnover (WBPT) independent of acidosis or uremia, we utilized a model of unilateral adriamycin nephrosis. Control rats were matched by weight to nephrotic rats and pair fed 22% protein chow for 14-18 days; urinary urea nitrogen (UUN) was measured on day 12, and leucine turnover measurement was performed on the final day. Growth rates of nephrotic and pair-fed control rats did not differ during the first 2 wk of pair feeding; thereafter, a small difference in growth could be detected. Despite an identical intake of dietary protein, UUN excretion was 29% less in the nephrotic rats (P < or = 0.02). Fasting whole body protein synthesis and degradation did not differ between nephrotic and control rats; in contrast, leucine oxidation decreased by 21% in nephrosis (P < 0.05). On the basis of near normal growth and normal rates of WBPT, we conclude that nephrotic rats fed ad libitum can adapt to the stress of continuous protein losses. A reduction in amino acid oxidation and UUN excretion were the primary mechanisms responsible for protein conservation in experimental nephrosis.

Nitrogen Homoeostasis in man: The Diurnal Responses of Protein Synthesis and Degradation and Amino Acid Oxidation to Diets with Increasing Protein Intakes

1994 ◽  
Vol 86 (1) ◽  
pp. 103-118 ◽  
Author(s):  
Paul J. Pacy ◽  
Gill M. Price ◽  
David Halliday ◽  
Marcello R. Quevedo ◽  
D. Joe Millward
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Dietary Protein ◽  
Protein Turnover ◽  
Protein Intake ◽  
Whole Body ◽  
Body Protein ◽  
Fed State ◽  
Leucine Kinetics ◽  
Synthesis And Degradation

1. The diurnal changes in whole body protein turnover associated with the increasing fasting body nitrogen (N) losses and feeding gains with increasing protein intake were investigated in normal adults. [13C]Leucine, [2H5]phenylalanine and [2H2]tyrosine kinetics, were measured during an 8h primed, continuous infusion during the fasting and feeding phase together with fed-state N turnover assessed with [15N]glycine after 12 days of adaptation to diets containing 0.36 (LP), 0.77 (MP), 1.59 (GP) and 2.07 (HP) g of protein day−1 kg−1. Measurements were also made of fasting and fed resting metabolic rate and plasma hormone levels. 2. Resting metabolic rate in the fasted and fed state was not influenced by dietary protein intake, but was increased by feeding (11-13%, P <0.01) with no influence of dietary protein concentration. Fasting plasma insulin levels were not influenced by protein intake and were increased by feeding independent of protein intake. Fasted but not fed values of insulinlike growth factor-1 increased with protein intake, although no feeding response was observed. Thyroid hormones (free and total tri-iodothyronine) did not change in any state. 3. For leucine with increasing protein intake the increasing fasting losses reflected increasing rates of protein degradation, although the changes were small and only significant between GP and MP intakes. The increasing leucine gain on feeding was associated with increasing rates of protein synthesis and falling rates of protein degradation, reflecting a progressive inhibition of degradation with feeding, and a change from inhibition of synthesis (LP diet) to stimulation (GP and HP diets). Mean daily rates of synthesis and degradation did not change with protein intake. 4. Phenylalanine and tyrosine kinetics were calculated from adjusted values based on leucine kinetics and published data of the hepatic/plasma enrichment ratio. With the increased protein intake, the increasing fasting losses of phenylalanine (GP > MP) were mediated by increasing rates of degradation (paired t-tests). The increasing phenylalanine gain (GP > MP > LP) was due to increasing fed-state rates of synthesis and falling rates of degradation, reflecting a progressive inhibition of degradation, a stimulation of hydroxylation and a variable response of synthesis ranging from inhibition at the lowest intake to stimulation at higher intakes. For tyrosine a similar progressive inhibition of degradation with intake was shown. Mean daily rates of synthesis and degradation (phenylalanine) and degradation (tyrosine) did not change with protein intake. 5. Estimation of protein turnover from 15N excretion in urea and ammonia during 9 h after 1 h intravenous infusion of [15N]glycine in the fed state on the LP, MP and GP diets indicated that neither synthesis nor degradation were influenced by dietary protein level. Synthesis estimated from 15N kinetics was significantly correlated with that determined from leucine kinetics (r = 0.78, n = 14, P <0.01) and from phenylalanine kinetics (r = 0.53, n = 14, P <0.05), and degradation estimated from 15N kinetics was significantly correlated with that determined from leucine kinetics (r = 0.60, n = 14, P <0.05). Thus the [15N]glycine, [13C]leucine and [2H5]phenylalanine methods gave broadly comparable results. 6. We conclude that the feeding response of protein synthesis, degradation and amino acid oxidation reflects the combined impact of insulin and tissue amino acid levels with insulin inhibiting degradation and with amino acids both stimulating synthesis and oxidation and also further inhibiting degradation. Although the dietary protein level influences the extent of these feeding responses, it does not influence the mean daily rate of protein turnover. The rate of whole body protein turnover per se is unlikely to provide an indicator of protein nutritional status.

scholarly journals Enhanced whole-body protein synthesis by methionine and arginine supplementation in protein-starved chicks

1986 ◽  
Vol 55 (3) ◽  
pp. 635-641 ◽  
Author(s):  
T. Muramatsu ◽  
M. Kato ◽  
I. Tasaki ◽  
J. Okumura
Keyword(s):  
Protein Synthesis ◽  
Body Weight Loss ◽  
Whole Body ◽  
Body Protein ◽  
Fractional Rate ◽  
Reduced Body ◽  
Significant Difference ◽  
Sparing Effect ◽  
Dose Injection ◽  
Synthesis And Degradation

1. The effect of supplementing with methionine alone or in combination with arginine on whole-body protein synthesis and degradation was studied in protein-starved chicks, fed on a protein-free (PF) diet, by a massive-dose injection of L-[4-3H]phenylalanine.2. Methionine or methionine and arginine (MA) supplementation reduced body-weight loss and improved N balance compared with unsupplemented controls.3. Whole-body protein synthesis was significantly increased both in terms of fractional rate and absolute amounts by methionine and MA addition, whereas the fractional degradation rate was unchanged.4. No significant difference was found between methionine and MA supplementation except for energy balance of the birds.5. It was concluded that the N-sparing effect of methionine or MA when added to a PF diet was primarily brought about by enhanced whole-body protein synthesis.

scholarly journals New perspectives in the control of body protein metabolism

2012 ◽  
Vol 108 (S2) ◽  
pp. S94-S104 ◽  
Author(s):  
Margaret A. McNurlan
Keyword(s):  
Protein Synthesis ◽  
Translational Control ◽  
Protein Metabolism ◽  
Gene Activation ◽  
Mrna Translation ◽  
Body Protein ◽  
Control Body ◽  
Long Term Impact ◽  
Protein Synthesis And Degradation ◽  
Synthesis And Degradation

Recent advances in elucidating the mechanisms that control body protein synthesis and degradation both expand and complicate our understanding of how these processes are regulated. This review presents an introduction to the multiple regulatory systems involved, emphasizing the number of potential controls. These include gene transcription, gene activation or suppression, activation or suppression of mRNA translation and activation or suppression of signaling pathways. The complexity of these interacting controls presents a challenge to our understanding of the overall coordinated regulation of protein synthesis and degradation and its response to any particular stimulus. Specific examples are used to illustrate regulatory mechanisms, including the ways in which protein metabolism is regulated by the amino acid leucine. In addition to regulation associated with gene expression and post-translational control, the expanding field of epigenetics adds another layer of complexity, including trans-generational responses to nutrient intake, highlighting the potential for long-term impact of nutritional experience on the metabolism of subsequent generations.

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