The effect of lactation on protein synthesis in ovine skeletal muscle

1982 ◽  
Vol 99 (2) ◽  
pp. 319-323 ◽  
Author(s):  
D. T. W. Bryant ◽  
R. W. Smith
Keyword(s):  
Protein Synthesis ◽  
Total Protein ◽  
Skeletal Muscles ◽  
Whole Body ◽  
Synthesis Rate ◽  
Longissimus Dorsi ◽  
Early Lactation ◽  
Lipid Contents ◽  
Plasma Tyrosine ◽  
Two Stages

SUMMARYProtein synthesis was measured in non-breeding sheep and in sheep at two stages of lactation by constant intravenous infusion of [3H] tyrosine. In early lactation plasma tyrosine flux was 50% higher than in non-breeding ewes and it remained somewhat higher in late lactation. Estimates of protein synthesis per day in the whole body showed similar changes.In early lactation the weights of the longissimus dorsi and semitendinosus muscles were respectively 37 and 28% lower than those for non-breeding ewes, but both muscles regained weight in late lactation. There were corresponding changes in the total protein, total RNA and total lipid contents of both muscles.The fractional rates of protein synthesis in the longissimus dorsi and the semitendinosus were between 2 and 3% per day, but it was higher in heart muscle. At both stages of lactation the synthesis rate in the longissimus dorsi was similar to that in nonbreeding ewes, but in the semitendinosus and in the heart synthesis rates were lower in lactating animals. In both skeletal muscles the total protein synthesized per day was lower in early lactation because their total protein contents were lower at this time. It is concluded that the maternal skeletal muscles may undergo a controlled depletion during lactation.

Protein synthesis in muscle of mature sheep

1982 ◽  
Vol 98 (3) ◽  
pp. 639-643 ◽  
Author(s):  
D. T. W. Bryant ◽  
R. W. Smith
Keyword(s):  
Body Weight ◽  
Protein Synthesis ◽  
Intravenous Infusion ◽  
Vastus Lateralis ◽  
Specific Radioactivity ◽  
Barley Straw ◽  
Whole Body ◽  
Longissimus Dorsi ◽  
Vastus Intermedius ◽  
Plasma Tyrosine

SUMMARYProtein synthesis was measured in wether sheep by constant intravenous infusion of [3H]tyrosine. The specific radioactivity of plasma tyrosine at plateau was used to calculate tyrosine flux and the rate of protein synthesis in the whole body was estimated. For wethers fed hay and concentrates tyrosine flux was 2·46 mmol/h and protein synthesized was 5·29 g/kg body weight per day. Corresponding values for wethers fed barley straw were 30–35% lower.Fractional rates of protein synthesis in individual muscles were between 2 and 3% per day for diaphragm, longissimus dorsi, gastrocnemius, semitendinosus and vastus lateralis muscles from wethers fed hay and concentrates, but the value for vastus intermedius was higher. Corresponding rates for wethers fed barley straw were 18–36% lower.

Leucine metabolism in lactating and dry goats: effect of insulin and substrate availability

1993 ◽  
Vol 265 (3) ◽  
pp. E402-E413 ◽  
Author(s):  
S. Tesseraud ◽  
J. Grizard ◽  
E. Debras ◽  
I. Papet ◽  
Y. Bonnet ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Degradation ◽  
Whole Body ◽  
Initial Slope ◽  
Sensitivity Index ◽  
Early Lactation ◽  
Dry Period ◽  
Body Protein ◽  
Lactating Goats

Early lactating goats show insulin resistance with respect to extramammary glucose utilization. However, much less is known about the two major factors, insulin and plasma amino acid concentration, that regulate protein metabolism in lactating goats. To examine this question, the in vivo effect of acute insulin was studied in goats during early lactation (12-31 days postpartum), midlactation (98-143 days postpartum), and the dry period (approximately 1 yr postpartum). Insulin was infused (at 0.36 or 1.79 nmol/min) under euglycemic and eukaliemic clamps. In addition, appropriate amino acid infusion was used to blunt insulin-induced hypoaminoacidemia or to create hyperaminoacidemia and maintain this condition under insulin treatment. Leucine kinetics were assessed using a primed continuous infusion of L-[1-14C]-leucine, which started 2.5 h before insulin. In all animals the insulin treatments failed to stimulate the nonoxidative leucine disposal (an estimate of whole body protein synthesis) under both euaminoacidemic and hyperaminoacidemic conditions. Thus, in goat as well as humans, infusion of insulin fails to stimulate protein synthesis even when combined with a substantially increased provision of amino acids. In contrast, insulin treatments caused a dose-dependent inhibition of the endogenous leucine appearance (an estimate of whole body protein degradation). Under euaminoacidemia the initial slope from the plot of the endogenous leucine appearance as a function of plasma insulin (an insulin sensitivity index) was steeper during early lactation than when compared with the dry period. A similar trend occurred during midlactation but not to any significant degree. These differences were abolished under hyperaminoacidemia. It was concluded that the ability of physiological insulin to inhibit protein degradation was improved during lactation, demonstrating a clear-cut dissociation between the effects of insulin on protein and glucose metabolism. This adaptation no doubt may provide a mechanism to save body protein.

Protein turnover in man measured with 15N: comparison of end products and dose regimes.

1978 ◽  
Vol 235 (2) ◽  
pp. E165 ◽  
Author(s):  
J C Waterlow ◽  
M H Golden ◽  
P J Garlick
Keyword(s):  
Protein Synthesis ◽  
Oral Dosage ◽  
Whole Body ◽  
Synthesis Rate ◽  
Obese Patients ◽  
Simple Method ◽  
Body Protein ◽  
End Products ◽  
Collection Period ◽  
Comparative Information

Whole-body protein synthesis was measured with [15N]glycine in malnourished and recovered infants and in obese patients. Comparisons were made: 1) between results obtained with single (S) and repeated (R) oral dosage of tracer; and 2) between urea and ammonia as end products. In the infants S and R gave similar values for the synthesis rate. With both methods of dosage, the values obtained with NH3 as end product were about two-thirds of those with urea. It is suggested that the cause of this result is that glycine contributes preferentially to the formation of urinary NH3. With NH3 as end product, a collection period of 12 h has been found to be suitable. With urea it is not possible to define an appropriate collection period. The combination of single dose of [15N]glycine with urinary NH3 as end product provides a simple method for measuring whole-body protein synthesis under clinical and field conditions. It can be repeated at short intervals and can give useful comparative information provided that conditions are carefully standardized. The reproducibility so far is +/- 13%.

scholarly journals Long-term modulation of type L pyruvate kinase activity in young and mature rats

1982 ◽  
Vol 204 (1) ◽  
pp. 329-338 ◽  
Author(s):  
Milinda E. James ◽  
James B. Blair
Keyword(s):  
Protein Synthesis ◽  
Pyruvate Kinase ◽  
Total Protein ◽  
Time Course ◽  
Enzyme Level ◽  
Enzyme Synthesis ◽  
Synthesis Rate ◽  
Adult Rats ◽  
Young Rats ◽  
Sucrose Diet

The regulation of type L pyruvate kinase concentrations in liver of young (35–45 days old) and adult (60–85 days old) rats starved and re-fed a 71% sucrose diet was investigated. Re-feeding is accompanied by an increase in the enzyme level in liver determined kinetically and immunologically. A constant ratio of kinetic activity to immunological activity was observed under all conditions examined, indicating that activity changes are the result of a regulation of synthesis or degradation and not an interconversion between kinetically active and inactive forms of the enzyme. Synthesis of pyruvate kinase was directly examined by using hepatocytes isolated from starved and re-fed rats. A stimulation of pyruvate kinase synthesis is observed on re-feeding. This increase in synthesis of pyruvate kinase is retained by the isolated hepatocyte for up to 7h in the absence of hormonal stimuli. Administration of glucagon (1μm) to the isolated hepatocytes had no influence on synthesis of pyruvate kinase and no evidence for a glucagon-directed degradation of the enzyme was found. Re-feeding the rat was followed by a transient increase in the synthesis of pyruvate kinase. The peak rate of synthesis was observed before a detectable increase in the enzyme concentration. After a rapid synthesis period, a new steady-state level of the enzyme was achieved and synthesis rates declined. The time course and magnitude for the response to the sucrose diet was dependent on the age of the rat. In young rats, an increase in pyruvate kinase synthesis is observed within 6h and peak synthesis occurs at 11h after re-feeding sucrose. The peak synthesis rate for pyruvate kinase for young rats represents approx. 1% of total protein synthesis. With adult rats, increased pyruvate kinase synthesis is not observed for 11h, with peak synthesis occurring at 24h after re-feeding. In the older rats, peak pyruvate kinase synthesis constitutes greater than 4% of total protein synthesis. Continued re-feeding of the adult rat beyond 24h is accompanied by a decline of pyruvate kinase synthesis to approx. 1.5% of total protein synthesis. The concentration of the enzyme, however, does not decline during this period, suggesting that control of pyruvate kinase degradation as well as synthesis occurs.

Enteral glutamine stimulates protein synthesis and decreases ubiquitin mRNA level in human gut mucosa

2003 ◽  
Vol 285 (2) ◽  
pp. G266-G273 ◽  
Author(s):  
Moïse Coëffier ◽  
Sophie Claeyssens ◽  
Bernadette Hecketsweiler ◽  
Alain Lavoinne ◽  
Philippe Ducrotté ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Cathepsin D ◽  
Mrna Level ◽  
Mass Spectrometry Analysis ◽  
Whole Body ◽  
Synthesis Rate ◽  
Mrna Levels ◽  
Human Gut ◽  
Mucosal Protein

Effects of glutamine on whole body and intestinal protein synthesis and on intestinal proteolysis were assessed in humans. Two groups of healthy volunteers received in a random order enteral glutamine (0.8 mmol·kg body wt-1·h-1) compared either to saline or isonitrogenous amino acids. Intravenous [2H5]phenylalanine and [13C]leucine were simultaneously infused. After gas chromatography-mass spectrometry analysis, whole body protein turnover was estimated from traced plasma amino acid fluxes and the fractional synthesis rate (FSR) of gut mucosal protein was calculated from protein and intracellular phenylalanine and leucine enrichments in duodenal biopsies. mRNA levels for ubiquitin, cathepsin D, and m-calpain were analyzed in biopsies by RT-PCR. Glutamine significantly increased mucosal protein FSR compared with saline. Glutamine and amino acids had similar effects on FSR. The mRNA level for ubiquitin was significantly decreased after glutamine infusion compared with saline and amino acids, whereas cathepsin D and m-calpain mRNA levels were not affected. Enteral glutamine stimulates mucosal protein synthesis and may attenuate ubiquitin-dependent proteolysis and thus improve protein balance in human gut.

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 The effect of a high dose of 3-hydroxy-3-methylbutyrate on protein metabolism in growing lambs

1997 ◽  
Vol 77 (6) ◽  
pp. 885-896 ◽  
Author(s):  
Isabelle Papet ◽  
Piotr Ostaszewski ◽  
Francoise Glomot ◽  
Christiane Obled ◽  
Magali Faure ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Free Amino Acid ◽  
Protein Metabolism ◽  
Free Amino ◽  
Skeletal Muscles ◽  
Whole Body ◽  
Control Group ◽  
High Dose ◽  
Body Protein

AbstractThe effect of a high dose of 3-hydroxy-3-methylbutyrate (HMB, a leucine catabolite) on protein metabolism was investigated in growing male lambs fed on hay and concentrate. Concentrate was supplemented with either Ca(HMB)2 (4g/kg) or Ca(C03)2 in experimental (HMB) and control groups respectively. Both groups consisted of six 2-month old lambs. Three complementary methods to study protein metabolism were carried out consecutively 2·5 months after beginning the dietary treatment: whole body phenylalanine fluxes, postprandial plasma free amino acid time course and fractional rates of protein synthesis in skeletal muscles. Feeding a high dose of HMB led to a significant increase in some plasma free amino acids compared with controls. Total, oxidative and non-oxidative phenylalanine fluxes were not modified by dietary HMB supplementation. Similarly, an acute infusion of HMB, in the control group, did not change these fluxes. In skeletal muscles, fractional rates of protein synthesis were not affected by long-term dietary supplementation with HMB. Taken together our results showed that administration of a high dose of HMB to lambs was able to modify plasma free amino acid pattern without any effect on whole-body protein turnover and skeletal muscle protein synthesis

Impairment of albumin and whole body postprandial protein synthesis in compensated liver cirrhosis

2002 ◽  
Vol 282 (2) ◽  
pp. E304-E311 ◽  
Author(s):  
P. Tessari ◽  
R. Barazzoni ◽  
E. Kiwanuka ◽  
G. Davanzo ◽  
G. De Pergola ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Liver Cirrhosis ◽  
Disease Stage ◽  
Whole Body ◽  
Synthesis Rate ◽  
Albumin Concentration ◽  
Mixed Meal ◽  
Body Protein ◽  
Control Subjects ◽  
Class B

To investigate the anabolic effects of feeding in cirrhosis, we measured albumin fractional synthesis rate (FSR) and whole body protein synthesis in six nondiabetic patients with stable liver cirrhosis (three in the Child-Pugh classification Class A, three in Class B) and in seven normal control subjects, before and after administration of a 4-h mixed meal. Leucine tracer precursor-product relationships and whole body kinetics were employed at steady state. Basal levels of postabsorptive albumin concentration and FSR, whole body leucine rate of appearance, oxidation, and nonoxidative leucine disposal (NOLD, ≈protein synthesis) were similar in the two groups. However, after the meal, in the patients neither albumin FSR (from 8.5 ± 1.5 to 8.8 ± 1.8 %/day) nor NOLD (from 1.69 ± 0.22 to 1.55 ± 0.26 μmol · kg−1· min−1) changed ( P = nonsignificant vs. basal), whereas they increased in control subjects (albumin FSR: from 10.9 ± 1.5 to 15.9 ± 1.9 %/day, P < 0.002; NOLD: from 1.80 ± 0.14 to 2.10 ± 0.19 μmol · kg−1· min−1, P = 0.032). Thus mixed meal ingestion did not stimulate either albumin FSR or whole body protein synthesis in compensated liver cirrhosis. The mechanism(s) maintaining normoalbuminemia at this disease stage need to be further investigated.

Effect of spaceflight on human protein metabolism

1993 ◽  
Vol 264 (5) ◽  
pp. E824-E828 ◽  
Author(s):  
T. P. Stein ◽  
M. J. Leskiw ◽  
M. D. Schluter
Keyword(s):  
Protein Synthesis ◽  
Nitrogen Balance ◽  
Protein Metabolism ◽  
Space Shuttle ◽  
Single Pulse ◽  
Whole Body ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Body Protein ◽  
Space Shuttle Columbia

Nitrogen balance and the whole body protein synthesis rate were measured before, during, and after a 9.5-day spaceflight mission on the space shuttle Columbia. Protein synthesis was measured by the single-pulse [15N]glycine method. Determinations were made 56, 26, and 18 days preflight, on flight days 2 and 8, and on days 0, 6, 14, and 45 postflight. We conclude that nitrogen balance was decreased during spaceflight. The decrease in nitrogen balance was greatest on the 1st day when food intake was reduced and again toward the end of the mission. An approximately 30% increase in protein synthesis above the preflight baseline was found for flight day 8 for all 6 subjects (P < 0.05), indicating that the astronauts showed a stress response to spaceflight.

scholarly journals Increased plasma Gln and Leu Raand inappropriately low muscle protein synthesis rate in AIDS wasting

1998 ◽  
Vol 275 (4) ◽  
pp. E577-E583 ◽  
Author(s):  
Kevin E. Yarasheski ◽  
Jeffrey J. Zachwieja ◽  
Jennifer Gischler ◽  
Jan Crowley ◽  
Mary M. Horgan ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Whole Body ◽  
Synthesis Rate ◽  
Protein Synthesis Rate ◽  
Asymptomatic Group ◽  
Body Protein ◽  
Asymptomatic Subjects ◽  
Muscle Protein Synthesis Rate

Muscle protein wasting occurs in human immunodeficiency virus (HIV)-infected individuals and is often the initial indication of acquired immunodeficiency syndrome (AIDS). Little is known about the alterations in muscle protein metabolism that occur with HIV infection. Nine subjects with AIDS wasting (CD4 < 200/mm3), chronic stable opportunistic infections (OI), and ≥10% weight loss, fourteen HIV-infected men and one woman (CD4 > 200/mm3) without wasting or OI (asymptomatic), and six HIV-seronegative lean men (control) received a constant intravenous infusion of [1-13C]leucine (Leu) and [2-15N]glutamine (Gln). Plasma Leu and Gln rate of appearance (Ra), whole body Leu turnover, disposal and oxidation rates, and [13C]Leu incorporation rate into mixed muscle protein were assessed. Total body muscle mass/fat-free mass was greater in controls (53%) than in AIDS wasting (43%; P = 0.04). Fasting whole body proteolysis and synthesis rates were increased above control in the HIV+ asymptomatic group and in the AIDS-wasting group ( P = 0.009). Whole body Leu oxidation rate was greater in the HIV+ asymptomatic group than in the control and AIDS-wasting groups ( P < 0.05). Fasting mixed muscle protein synthesis rate was increased in the asymptomatic subjects (0.048%/h; P = 0.01) but was similar in AIDS-wasting and control subjects (0.035 vs. 0.037%/h). Plasma Gln Rawas increased in AIDS-wasting subjects but was similar in control and HIV+ asymptomatic subjects ( P < 0.001). These findings suggest that AIDS wasting results from 1) a preferential reduction in muscle protein, 2) a failure to sustain an elevated rate of mixed muscle protein synthesis while whole body protein synthesis is increased, and 3) a significant increase in Gln release into the circulation, probably from muscle. Several interesting explanations for the increased Gln Rain AIDS wasting exist.

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