scholarly journals Protein synthesis in tissues of growing lambs

1981 ◽  
Vol 46 (3) ◽  
pp. 409-419 ◽  
Author(s):  
S. R. Davis ◽  
T. N. Barry ◽  
G. A. Hughson
Keyword(s):  
Protein Synthesis ◽  
Cardiac Muscle ◽  
Specific Radioactivity ◽  
Biceps Femoris ◽  
Whole Body ◽  
Tissue Homogenate ◽  
Body Protein ◽  
Tissue Protein ◽  
Biceps Femoris Muscle ◽  
Plasma Leucine

1. The fractional rate of protein synthesis (FSR) in tissues of nine growing lambs (4–5 months of age) was estimated following continuous infusion of L-[4,5–3H]leucine for a period of 7 h. Minimum and upper estimates of FSR were obtained assuming that the specific radioactivity (SRA) of leucine in blood plasma and tissue homogenate respectively defined that of leucyl tRNA.2. Mean upper estimates of tissue protein FSR (/d) were skin 0·35, longissimus dorsi muscle 0·05, biceps femoris muscle 0·04, liver 0·54, rumen 0·79, cardiac muscle 0·09. Minimum estimates of tissue protein FSR ranged from 0·03 (muscle) to 0·15 (liver).3. Plasma leucine flux was closely related to body protein content and dietary leucine absorption (r 0·94).4. The rate of whole-body protein synthesis (WBS) derived from plasma leucine flux corrected for oxidation and localized recycling of leucine into protein was similar to that calculated from the sum of daily protein synthesis in individual tissues using the upper estimate of FSR, i.e. 610 g/d v. 581 g/d.5. The estimate of WBS derived from plasma leucine flux directly (241 g/d) was similar to that calculated from the sum of minimum estimates of daily protein synthesis in individual tissues (214 g/d).6. The ratio, intracellular leucine SRA:plasma leucine SRA tended to increase with increasing dietary leucine absorption in all tissues although these factors were only significantly correlated (P < 0·05) in cardiac muscle, skin and rumen. Such relationships suggest an increased exchange of plasma leucine with intracellular leucine with increased food intake.7. It was estimated that the energy cost of protein synthesis accounted for approximately 42% of daily heat production.

scholarly journals Contribution of liver, skin and skeletal muscle to whole-body protein synthesis in the young lamb

1988 ◽  
Vol 60 (1) ◽  
pp. 77-84 ◽  
Author(s):  
D. Attaix ◽  
E. Aurousseau ◽  
A. Manghebati ◽  
M. Arnal
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Specific Radioactivity ◽  
Whole Body ◽  
Tissue Homogenate ◽  
Synthesis Rate ◽  
Body Protein ◽  
Tissue Protein ◽  
Large Injection ◽  
Tensor Fasciae Latae

1. Protein fractional synthesis rate (FSR) was measured in some major tissues and in the whole body of six 1-week-old sucking lambs by a large injection of L-[3H]valine.2. Upper estimates of tissue protein FSR (%/d), assuming that the tissue-homogenate free-valine specific radioactivity defined that of valyl tRNA, were 115.0 in liver, 24.1 in skin, 22.9 in the white M. tensor fasciae latae, 21.6 in the red M. diaphragma and 19–6 in the remainder (exsanguinated whole body without liver and gastrointestinal tract) of lambs.3. Absolute synthesis rates (ASR) of tissue protein were 17, 19 and 42 g/d in the liver, skin and skeletal muscle respectively, and 112 g/d in the remainder. The ASR of whole-body protein, derived from the tissue values, was 146 g/d, i.e. 33 g/d per kg body-weight. The calculated whole-body protein FSR was 23.9 %/d.4. The relative percentage contribution of liver, skin and skeletal muscle to whole-body protein synthesis was 11.7, 13.1, and 29.0.5. We concluded that tissue protein FSR in lambs were in exactly the same decreasing order, from visceral tissues to skeletal muscles, as observed in rats. The ovine FSR estimates and the partitioning of protein synthesis between tissues were in the same range as values recently obtained by flooding-dose experiments in immature rats, piglets, and even in chicks. These findings suggest that inter-species differences are rather limited.

scholarly journals Protein synthesis and growth in the gastrointestinal tract of the young preruminant lamb

1987 ◽  
Vol 58 (1) ◽  
pp. 159-169 ◽  
Author(s):  
D. Attaix ◽  
M. Arnal
Keyword(s):  
Protein Synthesis ◽  
Small Intestine ◽  
Gastrointestinal Tract ◽  
Specific Radioactivity ◽  
Whole Body ◽  
Tissue Homogenate ◽  
Body Protein ◽  
Tissue Protein ◽  
Precursor Pool ◽  
Gastrointestinal Tissue

1. In Expt 1, fractional synthesis rates (FSR) of tissue protein were measured along the gastrointestinal tract (GIT) of six 1-week-old, milk-fed lambs by using a large amount of L-[3,4(n)-3H]valine.2. In Expt 2, eighteen lambs were used to determine the fractional growth rate (FGR) of gastrointestinal tissue protein.3. FSRMinimum(Min) and FSRMaximum(Max) were calculated assuming plasma or tissue homogenate free valine specific radioactivity was representative of the valine precursor pool for protein synthesis. There were no significant differences between FSR(Min) and FSR(Max) in any gastrointestinal tissue of lambs used in Expt 1 (P > 0.05). FSR gradually and significantly (P > 0.05) increased from the oesophagus (FSR(Max)26.5%/d). reticulo-rumen (30.1%/d), omasum (41.0%/d) and abomasum (56.1%/d) to small intestine (87.5%/d), and then declined significantly (P < 0.05) towards the caecum (45.2%/d) and the colon (38.4%/d). No significant differences were observed between FSR in the duodenum, jejunum or ileum (P > 0.05).4. FGR ranged from 2,6%/d in the oesophagus to 8,7%/d in the omasum. The ratio, FGR:FSR, which reflected the efficiency of protein deposition, was at a maximum in the stomachs and caecum and at a minimum in the small intestine.5. The relative contribution of the oesophagus, stomachs, small intestine and large intestine to GIT protein synthesis was 1, 13, 76 and 10% respectively. The GIT accounted for approximately 11.5% of whole-body protein synthesis.

scholarly journals Whole body and tissue protein synthesis in cattle

1980 ◽  
Vol 43 (3) ◽  
pp. 491-502 ◽  
Author(s):  
G. E. Lobley ◽  
Vivien Milne ◽  
Joan M. Lovie ◽  
P. J. Reeds ◽  
K. Pennie
Keyword(s):  
Protein Synthesis ◽  
Total Synthesis ◽  
Total Protein ◽  
Specific Radioactivity ◽  
Live Weight ◽  
Whole Body ◽  
Tissue Homogenate ◽  
Body Protein ◽  
Tissue Protein ◽  
The Individual

The daily rates of synthesis of protein by the whole body and by the individual tissues were determined in two Hereford × Friesian heifers (236 kg and 263 kg live weight), and a dry Friesian cow (628 kg live weight).The rate of whole-body protein synthesis (g protein/d) was estimated from the total flux through the blood of [3H]leucine and [3H]tyrosine following infusion at a constant rate for 8 h.The fractional rates of protein synthesis (ks) in the tissues (g synthesized/d per g tissue protein) were obtained after slaughter of the animals at the end of the infusion period. The fractional rate of protein synthesis was calculated assuming that the specific radioactivity of free tyrosine in either the blood (to giveks, b) or the tissue homogenate (to giveks, h) defined closely the specific radioactivity of the amino acid precursor for protein synthesis. Total protein synthesis (As, borAs, h; g/d) in an individual tissue was calculated as the product ofks, b) (orks, h) × protein content.Based on the total leucine flux, i.e. without correction for oxidation, 1.6 kg protein were synthesized daily in the heifers; for the cow this value was 2.0 kg/d.The sum of the daily total synthesis in the major tissues (muscle+bone+brain, gastrointestinal tract (GIT), liver, hide) gave values of 1.4–1.9 kg/d based onAs, b, and 2.2–3.0 kg/d based onAs, h.The percentage contributions of the individual tissues to the total protein synthesis were similar in all three animals, for example based onAs, hmuscle was 12–16; carcass (muscle+bone+brain) 32–33; GIT 38–46; liver 7–8; skin 14–21%.The contribution of muscle to total synthesis estimated from the leucine flux was 19–22%; this value is in agreement with those calculated on the same basis for other species.The energy cost of protein synthesis was estimated to account for a maximum of 30% of heat production.

scholarly journals Tissue protein synthesis and nucleic acid concentrations in steers treated with somatotropin

1989 ◽  
Vol 62 (3) ◽  
pp. 657-671 ◽  
Author(s):  
J. H. Eisemann ◽  
A. C. Hammond ◽  
T. S. Rumsey
Keyword(s):  
Protein Synthesis ◽  
Small Intestine ◽  
Nucleic Acid ◽  
Specific Radioactivity ◽  
Whole Body ◽  
Tissue Homogenate ◽  
Synthesis Rate ◽  
Body Protein ◽  
Tissue Protein ◽  
Tissue Protein Synthesis

The effect of injection with bovine somatotropin (bST) on the fractional rate of protein synthesis (FSR) in tissues of beef steers was studied using a continuous infusion of [1-14C]leucine. Minimum and maximum FSR were calculated from free leucine specific radioactivity (SRA) in plasma or tissue homogenate respectively. Tissue nucleic acid concentrations were also quantified. Tissue samples were obtained from several muscles, sections of the small intestine and liver. In response to bST, both minimum and maximum FSR increased in muscle but not liver or intestinal tissues. Absolute synthesis rate increased in several muscles and small intestine tissues. Treatment with bST increased the relative SRA of protein-bound leucine in muscles compared with liver; increased the amount of protein synthesis per unit empty body-weight (EBW) in most muscles; and increased weight of small intestine relative to EBW, suggesting a differential response between liver and the other tissues measured. Compositional changes in response to bST occurred only in muscles. DNA concentration increased while protein:DNA decreased in the gastrocnemius muscle and RNA:DNA increased in the longissimus dorsi. The maximum percentage contribution of tissue protein synthesis to whole-body protein synthesis was 12·6, 25·7 and 20·5, and 13·0, 29·4 and 25·8 for liver, muscle, and small intestine in placebo-treated and bST-injected steers respectively.

Measurement of protein turnover in the small intestine of lambs. 2. Effects of feed intake

1997 ◽  
Vol 128 (2) ◽  
pp. 233-246 ◽  
Author(s):  
S. A. NEUTZE ◽  
J. M. GOODEN ◽  
V. H. ODDY
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Small Intestine ◽  
Experimental Model ◽  
Feed Intake ◽  
Protein Turnover ◽  
Jugular Vein ◽  
Specific Radioactivity ◽  
Whole Body ◽  
Body Protein

This study used an experimental model, described in a companion paper, to examine the effects of feed intake on protein turnover in the small intestine of lambs. Ten male castrate lambs (∼ 10 months old) were offered, via continuous feeders, either 400 (n = 5) or 1200 (n = 5) g/day lucerne chaff, and mean experimental liveweights were 28 and 33 kg respectively. All lambs were prepared with catheters in the cranial mesenteric vein (CMV), femoral artery (FA), jugular vein and abomasum, and a blood flow probe around the CMV. Cr-EDTA (0·139 mg Cr/ml, ∼ 0·2 ml/min) was infused abomasally for 24 h and L-[2,6-3H]phenylalanine (Phe) (420±9·35 μCi into the abomasum) and L-[U-14C]phenylalanine (49·6±3·59 μCi into the jugular vein) were also infused during the last 8 h. Blood from the CMV and FA was sampled during the isotope infusions. At the end of infusions, lambs were killed and tissue (n = 4) and digesta (n = 2) samples removed from the small intestine (SI) of each animal. Transfers of labelled and unlabelled Phe were measured between SI tissue, its lumen and blood, enabling both fractional and absolute rates of protein synthesis and gain to be estimated.Total SI mass increased significantly with feed intake (P < 0·05), although not on a liveweight basis. Fractional rates of protein gain in the SI tended to increase (P = 0·12) with feed intake; these rates were −16·2 (±13·7) and 23·3 (±15·2) % per day in lambs offered 400 and 1200 g/day respectively. Mean protein synthesis and fractional synthesis rates (FSR), calculated from the mean retention of 14C and 3H in SI tissue, were both positively affected by feed intake (0·01 < P < 0·05). The choice of free Phe pool for estimating precursor specific radioactivity (SRA) for protein synthesis had a major effect on FSR. Assuming that tissue free Phe SRA represented precursor SRA, mean FSR were 81 (±15) and 145 (±24) % per day in lambs offered 400 and 1200 g/day respectively. Corresponding estimates for free Phe SRA in the FA and CMV were 28 (±2·9) and 42 (±3·5) % per day on 400 g/day, and 61 (±2·9) and 94 (±6·0) on 1200 g/day. The correct value for protein synthesis was therefore in doubt, although indirect evidence suggested that blood SRA (either FA or CMV) may be closest to true precursor SRA. This evidence included (i) comparison with flooding dose estimates of FSR, (ii) comparison of 3H[ratio ]14C Phe SRA in free Phe pools with this ratio in SI protein, and (iii) the proportion of SI energy use associated with protein synthesis.Using the experimental model, the proportion of small intestinal protein synthesis exported was estimated as 0·13–0·27 (depending on the choice of precursor) and was unaffected by feed intake. The contribution of the small intestine to whole body protein synthesis tended to be higher in lambs offered 1200 g/day (0·21) than in those offered 400 g/day (0·13). The data obtained in this study suggested a role for the small intestine in modulating amino acid supply with changes in feed intake. At high intake (1200 g/day), the small intestine increases in mass and CMV uptake of amino acids is less than absorption from the lumen, while at low intake (400 g/day), this organ loses mass and CMV uptake of amino acids exceeds that absorbed. The implications of these findings are discussed.

Whole body protein synthesis: studies with different amino acids in the rat

1989 ◽  
Vol 257 (5) ◽  
pp. E639-E646 ◽  
Author(s):  
C. Obled ◽  
F. Barre ◽  
D. J. Millward ◽  
M. Arnal
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Turnover ◽  
Specific Radioactivity ◽  
Whole Body ◽  
Body Protein ◽  
Tissue Specific ◽  
Dose Method ◽  
Infusion Method

These studies were undertaken to determine to what extent constant infusion measurements and plasma sampling could provide sensible answers for rates of whole body protein turnover and also which amino acid would be the most representative probe of whole body protein turnover. Whole body protein synthesis rates were estimated in 70-g rats with L-[U-14C]threonine, L-[U-14C]lysine, L-[U-14C]tyrosine, L-[U-14C]phenylalanine, and L-[1-14C]leucine by either simultaneous tracer infusion of four amino acids or by injections of large quantities of 14C-labeled amino acids. In the infusion experiment, indirect estimates of whole body protein turnover based on free amino acid specific radioactivity and stochastic modeling were compared with direct measurement of the incorporation of the tracer into proteins. These two methods of analysis provided similar results for each amino acid, although in each case fractional synthesis rates were lower (by between 26 and 63%) when calculations were based on plasma rather than tissue specific radioactivity. With the flooding-dose method, whole body fractional protein synthesis rates were 41.4, 25.6, 31.1, and 31.4% with threonine, lysine, phenylalanine, and leucine, respectively. These values were similar to those obtained by the continuous infusion method using tissue specific radioactivity for threonine and lysine. For leucine, however, the flooding-dose method provided an intermediate value between the two estimates derived either from the plasma or the tissue specific radioactivity in the infusion method.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Whole body and tissue fractional protein synthesis in the ovine fetusin utero

1984 ◽  
Vol 52 (2) ◽  
pp. 359-369 ◽  
Author(s):  
A. L. Schaefer ◽  
C. R. Krishnamurti
Keyword(s):  
Protein Synthesis ◽  
Activity Ratio ◽  
Specific Activity ◽  
Whole Body ◽  
Absolute Rate ◽  
Body Protein ◽  
Tissue Protein ◽  
Fractional Rate ◽  
Tyrosine Concentration

1. Whole-body and tissue fractional protein synthesis rates were determined in chronically-catheterized ovine fetuses at 120–130 d of gestation following an 8 h continuous infusion of L-[U-14C]-or L-[2, 3, 5, 6-3H]tyrosine.2. From the net utilization of tyrosine by the fetus, corrected for apparent oxidation, and tyrosine concentration in the fetal carcass protein, whole-body protein synthesis was estimated to be 63 g/d per kg.3. Following 8 h of infusion of labelled tyrosine the ewes were killed and fetal tissues were removed for the determination of tyrosine specific activity. The fractional rate of protein synthesis (k3) was calculated from the specific activity ratio, protein bound: intracellular free tyrosine. Tissue k, values for the liver, kidney, lungs, brain, skeletal muscle and small intestine were 78, 45, 65, 37, 26 and 93% /d respectively.4. The absolute rate of synthesis was calculated by multiplying the tissue protein content by k2. Muscles, gastrointestinal tract, liver and lungs contributed approximately 20.5, 20.5, 14.4 and 9.4% respectively to whole- body protein synthesis.5. The efficiency of protein synthesis as expressed by the RNA activity was higher in liver, lung and brain followed by kidney, skeletal and cardiac muscle.

Use of the constant infusion technique for measuring rates of protein synthesis in the New Zealand White rabbit

1977 ◽  
Vol 38 (1) ◽  
pp. 1-17 ◽  
Author(s):  
G. A. Nicholas ◽  
G. E. Lobley ◽  
C. I. Harris
Keyword(s):  
Protein Synthesis ◽  
New Zealand ◽  
Specific Radioactivity ◽  
Whole Body ◽  
Constant Infusion ◽  
Side Chain ◽  
List Type ◽  
Liver Protein ◽  
Body Protein ◽  
Infusion Technique

1.To study the potential of the constant-infusion technique for measuring rates of protein synthesis in New Zealand White rabbits, animals were infused for up to 6 h with radioactively-labelled tyrosine.2.Labelled tyrosine from plasma and tissues was isolated from labelled metabolites by ion-exchange chromatography.3.Analysis of serial blood and muscle biopsy samples removed under anaesthesia showed that the specific radioactivity (SR) of the free tyrosine pools reached an approximately constant value within 2 h.4.Certain commercial preparations of L-[side-chain 2,3-3H]tyrosine were contaminated with 300 mg radioactive D-tyrosine/g. The D-isomer appeared to enter the muscle intracellular pool.5.In constant-infusion experiments L-[3H]tyrosine could replace the uniformly-14C-labelled L-isomer for the determination of rates of protein synthesis in muscle. L-[side-chain 2,3-3H]tyrosine may not be suitable for use as a precursor for measuring rates of liver protein synthesis.6.Evidence is presented that the precursor of liver protein synthesis may not be well defined by the SR for free tyrosine of the homogenate.7.The technique was used to measure the rates of protein synthesis in adult rabbits. The rates of protein synthesis in liver and muscle were measured and from measurements of tyrosine flux the mean rate of whole-body protein synthesis was calculated as 13.8 g/kg per d.

Whole-body and tissue protein synthesis during brief and prolonged fasting in the rat

1991 ◽  
Vol 81 (5) ◽  
pp. 611-619 ◽  
Author(s):  
Yves Cherel ◽  
Didier Attaix ◽  
Danuta Rosolowska-Huszcz ◽  
Rajae Belkhou ◽  
Jean-Patrice Robin ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Skeletal Muscles ◽  
Whole Body ◽  
Protein Loss ◽  
Body Protein ◽  
Tissue Protein ◽  
Control Value ◽  
Tissue Protein Synthesis ◽  
Fractional Synthesis

1. Little information is currently available on protein turnover during chronic protein loss situations. We have thus measured the whole-body and tissue protein fractional synthesis rates (ks), the whole-body fractional protein degradation rate (kd), the capacity for protein synthesis (Cs) and the efficiency of protein synthesis (kRNA) in vivo in fed and fasted (1, 5 and about 9 days) 400 g rats. 2. One day of starvation resulted in a reduced ks and an increased kd in the whole body. ks was selectively depressed in skeletal muscles, mainly owing to a reduced kRNA, and was not modified in heart, liver and skin. The contribution of skin to whole-body protein synthesis increased by 39%. 3. During the phase of protein sparing (5 days of fasting), kd in the whole body decreased below the control fed level. ks in skeletal muscles was sustained because kRNA was restored to 82–98% of the control value. 4. Rats were in a protein-wasting phase after 9 days of starvation. kd in the whole body did not increase and was actually 78% of the value observed in fed animals. By contrast, ks in the whole body and tissues decreased to 14–34% of the control values, owing to reductions in both Cs and kRNA. Whatever the duration of the fast, the contribution of the skin to whole-body protein synthesis largely exceeded that of skeletal muscle. 5. The present findings suggest that the main goal in the treatment of chronic protein loss should be to sustain protein synthesis. Our data also emphasize the importance of skin in whole-body protein synthesis in fasting and possibly in other protein loss situations.

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