Effect of Exercise on Protein Turnover in Man

1981 ◽  
Vol 61 (5) ◽  
pp. 627-639 ◽  
Author(s):  
M. J. Rennie ◽  
R. H. T. Edwards ◽  
S. Krywawych ◽  
C. T. M. Davies ◽  
D. Halliday ◽  
...  
Keyword(s):  
Amino Acid ◽  
Protein Turnover ◽  
Whole Body ◽  
Protein Breakdown ◽  
Body Protein ◽  
Fractional Rate ◽  
Plasma And Urine Samples ◽  
Amino Acid Concentrations ◽  
Substantial Rise

1. We have investigated the effects of moderate long-term exercise on protein turnover in fed man by measuring the extent of whole-body nitrogen production, the labelling of urinary ammonia from ingested [15N]glycine and plasma, muscle and urine free amino acid concentrations. 2. Judged both from nitrogen production, and from the extent of 13CO2 production from ingested l-[l-13C]leucine, exercise causes a substantial rise in amino acid catabolism. 3. Amino acids catabolized during exercise appear to become available through a fall in whole-body protein synthesis and a rise in whole-body protein breakdown. After exercise, protein balance becomes positive through a rise in the rate of whole-body synthesis in excess of breakdown. 4. Studies of free 3-methylhistidine in muscle, plasma and urine samples suggest that exercise decreases the fractional rate of myofibrillar protein breakdown, in contrast with the apparent rise in whole-body breakdown.

scholarly journals Correction of acidosis in hemodialysis decreases whole-body protein degradation.

1997 ◽  
Vol 8 (4) ◽  
pp. 632-637 ◽  
Author(s):  
K A Graham ◽  
D Reaich ◽  
S M Channon ◽  
S Downie ◽  
T H Goodship
Keyword(s):  
Renal Failure ◽  
Protein Degradation ◽  
Protein Turnover ◽  
Whole Body ◽  
Body Protein ◽  
Chronic Metabolic Acidosis ◽  
Optimal Correction ◽  
Kinetics Of ◽  
Amino Acid Concentrations

Correction of acidosis in hemodialysis (HD) decreases protein degradation. The effect of the correction of chronic metabolic acidosis in chronic renal failure patients treated with HD was determined from the kinetics of infused L-[1-(13)C]leucine. Six HD patients were studied before (acid) and after (bicarbonate) correction of acidosis (pH: acid 7.36 +/- 0.01, bicarbonate 7.40 +/- 0.01, P < 0.005). Leucine appearance from body protein (PD) and leucine disappearance into body protein (PS) decreased significantly with correction of acidosis (PD: acid 180.6 +/- 7.3, bicarbonate 130.9 +/- 7.2 mumol.kg-1.h-1, P < 0.005; PS: acid 172.3 +/- 6.8, bicarbonate 122.0 +/- 6.8 mumol.kg-1.h-1, P < 0.005). There was no significant change in leucine oxidation or plasma amino acid concentrations. These results demonstrate that optimal correction of acidosis in HD is beneficial in terms of protein turnover and may improve long-term nutritional status in HD.

scholarly journals Effects of long-term protein excess or deficiency on whole-body protein turnover in sheep nourished by intragastric infusion of nutrients

1995 ◽  
Vol 73 (6) ◽  
pp. 829-839 ◽  
Author(s):  
S. M. Liu ◽  
G. E. Lobley ◽  
N. A. Macleod ◽  
D. J. Kyle ◽  
X.B. Chen ◽  
...  
Keyword(s):  
Dietary Protein ◽  
Protein Turnover ◽  
Protein Intake ◽  
Volatile Fatty Acids ◽  
Whole Body ◽  
N Losses ◽  
Body Protein ◽  
Fractional Rate ◽  
The Difference

The effect of long-term dietary protein excess and deficit on whole-body protein-N turnover (WBPNT) was examined in lambs nourished by intragastric infusions of nutrients. Ten sheep were given 500 mg N/kg metabolic weight (W0.75) per d from casein for 2 weeks and then either 50 (L), 500 (M) or 1500 (H) mg N/kgW0.75per d for 6 weeks. Volatile fatty acids were infused at 500 kJ/kgW0.75per d. Daily WBPNT was measured by continuous intravenous infusion of [l-13C]leucine 3 d before, and on days 2, 21 and 42 after the alteration in protein intake. Whole-body protein-N synthesis (WBPNS) was calculated as the difference between WBPNT and the protein-N losses as urinary NH3and urea. Whole-body protein-N degradation (WBPNS) was then estimated from WBPNS minus protein gain determined from N balance. Fractional rates of WBPNS and WBPND were calculated against fleece-free body N content. WBPNS rates at the L, M and H intakes were respectively 35·1, 41·5 amd 6·37 g/d (P< 0.001) on average over the 6 weeks and WBPND rates were 39·5, 41·1 and 56·8 g/d (P< 0.001). The fractional rates of WBPNS were 5·01, 6·37 and 7·73% per d (P< 0.001) while those of WBPND were 5·64, 6·29 and 6·81% per d (P< 0.005) respectively. On days 2, 21 and 42, WBPNS rates at intake H were 54·0, 61·8 and 75·4 g/d (P= 0·03) respectively, and WBPND rates were 43·2, 56·4 and 70·9 g/d (P= 0.03); at intake L the amounts were 38·2, 34·2 and 32·8 g/d for WBPNS (P= 0.003) and for WBPND were 43·4, 38·0 and 36·9 g/d (P= 0·016) respectively. There were no significant (P> 0·05) differences in fractional rates of WBPNS and WBPND with time at either the L or H intake. We concluded that absolute protein turnover was affected both by dietary protein intake and by body condition while the fractional rate of turnover was predominantly influenced by intake.

Ammonium chloride-induced acidosis increases protein breakdown and amino acid oxidation in humans

1992 ◽  
Vol 263 (4) ◽  
pp. E735-E739 ◽  
Author(s):  
D. Reaich ◽  
S. M. Channon ◽  
C. M. Scrimgeour ◽  
T. H. Goodship
Keyword(s):  
Amino Acid ◽  
Ammonium Chloride ◽  
Protein Turnover ◽  
Healthy Subjects ◽  
Whole Body ◽  
Acid Oxidation ◽  
Protein Breakdown ◽  
Body Protein ◽  
Amino Acid Oxidation ◽  
Kinetics Of

The effect of acidosis on whole body protein turnover was determined from the kinetics of infused L-[1-13C]leucine. Seven healthy subjects were studied before (basal) and after (acid) the induction of acidosis with 5 days oral ammonium chloride (basal pH 7.42 +/- 0.01, acid pH 7.35 +/- 0.03). Bicarbonate recovery, measured from the kinetics of infused NaH13CO3, was increased in the acidotic state (basal 72.9 +/- 1.2 vs. acid 77.6 +/- 1.6%; P = 0.06). Leucine appearance from body protein (PD), leucine disappearance into body protein (PS), and leucine oxidation (O) increased significantly (PD: basal 120.5 +/- 5.6 vs. acid 153.9 +/- 6.2, P < 0.01; PS: basal 98.8 +/- 5.6 vs. acid 127.0 +/- 4.7, P < 0.01; O: basal 21.6 +/- 1.1 vs. acid 26.9 +/- 2.3 mumol.kg-1.h-1, P < 0.01). Plasma levels of the amino acids threonine, serine, asparagine, citrulline, valine, leucine, ornithine, lysine, histidine, arginine, and hydroxyproline increased significantly with the induction of acidosis. These results confirm that acidosis in humans is a catabolic factor stimulating protein degradation and amino acid oxidation.

Glutamine kinetics and protein turnover in end-stage renal disease

2005 ◽  
Vol 288 (1) ◽  
pp. E37-E46 ◽  
Author(s):  
Dominic S. C. Raj ◽  
Tomas Welbourne ◽  
Elizabeth A. Dominic ◽  
Debra Waters ◽  
Robert Wolfe ◽  
...  
Keyword(s):  
Amino Acid ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Whole Body ◽  
Protein Breakdown ◽  
Protein Catabolism ◽  
Body Protein ◽  
Muscle Protein Breakdown ◽  
Stage Renal Disease ◽  
End Stage

Alanine and glutamine constitute the two most important nitrogen carriers released from the muscle. We studied the intracellular amino acid transport kinetics and protein turnover in nine end-stage renal disease (ESRD) patients and eight controls by use of stable isotopes of phenylalanine, alanine, and glutamine. The amino acid transport kinetics and protein turnover were calculated with a three-pool model from the amino acid concentrations and enrichment in the artery, vein, and muscle compartments. Muscle protein breakdown was more than synthesis (nmol·min−1·100 ml leg−1) during hemodialysis (HD) (169.8 ± 20.0 vs. 125.9 ± 21.8, P < 0.05) and in controls (126.9 ± 6.9 vs. 98.4 ± 7.5, P < 0.05), but synthesis and catabolism were comparable pre-HD (100.7 ± 15.7 vs. 103.4 ± 14.8). Whole body protein catabolism decreased by 15% during HD. The intracellular appearance of alanine (399.0 ± 47.1 vs. 243.0 ± 34.689) and glutamine (369.7 ± 40.6 vs. 235.6 ± 27.5) from muscle protein breakdown increased during dialysis (nmol·min−1·100 ml leg−1, P < 0.01). However, the de novo synthesis of alanine (3,468.9 ± 572.2 vs. 3,140.5 ± 467.7) and glutamine (1,751.4 ± 82.6 vs. 1,782.2 ± 86.4) did not change significantly intradialysis (nmol·min−1·100 ml leg−1). Branched-chain amino acid catabolism (191.8 ± 63.4 vs. −59.1 ± 42.9) and nonprotein glutamate disposal (347.0 ± 46.3 vs. 222.3 ± 43.6) increased intradialysis compared with pre-HD (nmol·min−1·100 ml leg−1, P < 0.01). The mRNA levels of glutamine synthase (1.45 ± 0.14 vs. 0.33 ± 0.08, P < 0.001) and branched-chain keto acid dehydrogenase-E2 (3.86 ± 0.48 vs. 2.14 ± 0.27, P < 0.05) in the muscle increased during HD. Thus intracellular concentrations of alanine and glutamine are maintained during HD by augmented release of the amino acids from muscle protein catabolism. Although muscle protein breakdown increased intradialysis, the whole body protein catabolism decreased, suggesting central utilization of amino acids released from skeletal muscle.

scholarly journals Impact of habituated dietary protein intake on fasting and postprandial whole-body protein turnover and splanchnic amino acid metabolism in elderly men: a randomized, controlled, crossover trial

2020 ◽  
Vol 112 (6) ◽  
pp. 1468-1484 ◽  
Author(s):  
Grith Højfeldt ◽  
Jacob Bülow ◽  
Jakob Agergaard ◽  
Ali Asmar ◽  
Peter Schjerling ◽  
...  
Keyword(s):  
Amino Acid ◽  
Protein Turnover ◽  
Protein Intake ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
High Protein ◽  
Whole Body ◽  
Body Protein ◽  
Protein Absorption ◽  
Fasted State

ABSTRACT Background Efficacy of protein absorption and subsequent amino acid utilization may be reduced in the elderly. Higher protein intakes have been suggested to counteract this. Objectives We aimed to elucidate how habituated amounts of protein intake affect the fasted state of, and the stimulatory effect of a protein-rich meal on, protein absorption, whole-body protein turnover, and splanchnic amino acid metabolism. Methods Twelve men (65–70 y) were included in a double-blinded crossover intervention study, consisting of a 20-d habituation period to a protein intake at the RDA or a high amount [1.1 g · kg lean body mass (LBM)−1 · d−1 or &gt;2.1 g · kg LBM−1 · d−1, respectively], each followed by an experimental trial with a primed, constant infusion of D8-phenylalanine and D2-tyrosine. Arterial and hepatic venous blood samples were obtained after an overnight fast and repeatedly 4 h after a standardized meal including intrinsically labeled whey protein concentrate and calcium-caseinate proteins. Blood was analyzed for amino acid concentrations and phenylalanine and tyrosine tracer enrichments from which whole-body and splanchnic amino acid and protein kinetics were calculated. Results High (compared with the recommended amount of) protein intake resulted in a higher fasting whole-body protein turnover with a resultant mean ± SEM 0.03 ± 0.01 μmol · kg LBM−1 · min−1 lower net balance (P &lt; 0.05), which was not rescued by the intake of a protein-dense meal. The mean ± SEM plasma protein fractional synthesis rate was 0.13 ± 0.06%/h lower (P &lt; 0.05) after habituation to high protein. Furthermore, higher fasting and postprandial amino acid removal were observed after habituation to high protein, yielding higher urea excretion and increased phenylalanine oxidation rates (P &lt; 0.01). Conclusions Three weeks of habituation to high protein intake (&gt;2.1 g protein · kg LBM−1 · d−1) led to a significantly higher net protein loss in the fasted state. This was not compensated for in the 4-h postprandial period after intake of a meal high in protein. This trial was registered at clinicaltrials.gov as NCT02587156.

Effect of dietary protein and energy intakes on whole-body protein turnover and its contribution to heat production in chicks

1993 ◽  
Vol 69 (3) ◽  
pp. 681-688 ◽  
Author(s):  
K. Kita ◽  
T. Muramatsu ◽  
J. Okumura
Keyword(s):  
Protein Synthesis ◽  
Heat Production ◽  
Protein Turnover ◽  
Crude Protein ◽  
Total Heat ◽  
Interactive Effects ◽  
Whole Body ◽  
Small Range ◽  
Body Protein ◽  
Fractional Rate

A factorial 3 × 3 experiment was conducted with chicks to investigate the effect of manipulating crude protein (N × 6.25) intake (CPI) and metabolizable energyintake (MEI) simultaneously, in the range low to high (including adequate) levels with regard to the respective requirements, on whole-body protein turnover and its contribution to total heat production. The fractional rate of whole-body protein synthesis was increased curvilinearly by increasing MEI or CPI from low to high levels. In terms of absolute rates whole-body protein synthesis was enhanced by increasing MEI from low to adequate levels, the effect being greater at adequate and high CPI than at low CPI. The effect of varying CPI and MEI on whole-body protein degradation was similar, but less sensitive, to that on whole-body protein synthesis. Increasing MEI from low to high levels elevated totalheat production at all CPI levels. There were no interactive effects of varying CPI andMEI on the contribution of whole-body protein synthesis to total heat production, and in general the contribution increased with increasing CPI and decreased with increasing MEI.The contribution of whole-body protein synthesis to total heat production fell within a small range from 11.2 to 16.5%.

Fasting and postprandial phenylalanine and leucine kinetics in liver cirrhosis

1994 ◽  
Vol 267 (1) ◽  
pp. E140-E149 ◽  
Author(s):  
P. Tessari ◽  
S. Inchiostro ◽  
R. Barazzoni ◽  
M. Zanetti ◽  
R. Orlando ◽  
...  
Keyword(s):  
Liver Cirrhosis ◽  
Protein Turnover ◽  
Normal Subjects ◽  
Whole Body ◽  
Protein Breakdown ◽  
Phenylalanine Concentration ◽  
Mixed Meal ◽  
Body Protein ◽  
Plasma Phenylalanine ◽  
Leucine Kinetics

To investigate body protein turnover and the pathogenesis of increased concentration of plasma phenylalanine in liver cirrhosis, we have studied phenylalanine and leucine kinetics in cirrhotic (diabetic and nondiabetic) patients, and in normal subjects, both in the postabsorptive state and during a mixed meal, using combined intravenous and oral isotope infusions. Postabsorptive phenylalanine concentration and whole body rate of appearance (Ra) were approximately 40% greater (P < 0.05) in patients than in controls. Leucine concentrations were comparable, but intracellular leucine Ra was also increased (P < 0.05), suggesting increased whole body protein breakdown. Postprandial phenylalanine Ra was also greater (P < 0.05) in the patients. This difference was due to a diminished fractional splanchnic uptake of the dietary phenylalanine (approximately 40% lower in the cirrhotics vs. controls, P < or = 0.05). Postprandial leucine Ra was also increased in the patients, but splanchnic uptake of dietary leucine was normal. Thus both increased body protein breakdown and decreased splanchnic extraction of dietary phenylalanine can account for the increased phenylalanine concentrations in liver cirrhosis.

Role of ovarian hormones in the regulation of protein metabolism in women: effects of menopausal status and hormone replacement therapy

2006 ◽  
Vol 291 (3) ◽  
pp. E639-E646 ◽  
Author(s):  
Michael J. Toth ◽  
Cynthia K. Sites ◽  
Dwight E. Matthews
Keyword(s):  
Postmenopausal Women ◽  
Protein Metabolism ◽  
Protein Turnover ◽  
Hormone Replacement ◽  
Menopausal Status ◽  
Ovarian Hormones ◽  
Hormone Deficiency ◽  
Whole Body ◽  
Protein Breakdown ◽  
Body Protein

The age-related decline in fat-free mass is accelerated in women after menopause, implying that ovarian hormone deficiency may have catabolic effects on lean tissue. Because fat-free tissue mass is largely determined by its protein content, alterations in ovarian hormones would likely exert regulatory control through effects on protein balance. To address the hypothesis that ovarian hormones regulate protein metabolism, we examined the effect of menopausal status and hormone replacement therapy (HRT) on protein turnover. Whole body protein breakdown, oxidation, and synthesis were measured under postabsorptive conditions using [13C]leucine in healthy premenopausal ( n = 15, 49 ± 1 yr) and postmenopausal ( n = 18, 53 ± 1 yr) women. In postmenopausal women, whole body protein turnover and plasma albumin synthesis rates (assessed using [13C]leucine and [2H]phenylalanine) were also measured following 2 mo of treatment with oral HRT (0.625 mg conjugated estrogens + 2.5 mg medroxyprogesterone acetate, n = 9) or placebo ( n = 9). No differences in whole body protein breakdown, oxidation, or synthesis were found between premenopausal and postmenopausal women. Protein metabolism remained similar between groups after statistical adjustment for differences in adiposity and when subgroups of women matched for percent body fat were compared. In postmenopausal women, no effect of HRT was found on whole body protein breakdown, synthesis, or oxidation. In contrast, our results support a stimulatory effect of HRT on albumin fractional synthesis rate, although this did not translate into alterations in circulating albumin concentrations. In conclusion, our results suggest no detrimental effect of ovarian hormone deficiency coincident with the postmenopausal state, and no salutary effect of hormone repletion with HRT, on rates of whole body protein turnover, although oral HRT regimens may increase the synthesis rates of albumin.

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