Protein Synthesis in the Small Intestine Seromuscular Layer is Insensitive to Re-Feeding

1993 ◽  
Vol 84 (s28) ◽  
pp. 10P-10P ◽  
Author(s):  
J S Marway ◽  
T Siddiq ◽  
J Teare ◽  
V R Preedy
Keyword(s):  
Protein Synthesis ◽  
Small Intestine ◽  
Seromuscular Layer

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.

Prevention of skeletal muscle catabolism in sepsis does not impair visceral protein metabolism

1996 ◽  
Vol 270 (4) ◽  
pp. E621-E626 ◽  
Author(s):  
R. N. Cooney ◽  
E. Owens ◽  
D. Slaymaker ◽  
T. C. Vary
Keyword(s):  
Protein Synthesis ◽  
Small Intestine ◽  
Protein Content ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Interleukin 1 ◽  
Intestinal Protein ◽  
Muscle Catabolism ◽  
Induced Changes ◽  
Septic Insult

We investigated whether the preservation of gastrocnemius proteins by interleukin-1 receptor antagonist (IL-1ra) during sepsis altered protein metabolism in visceral tissues. Sepsis was induced by creation of an abdominal abscess followed by infusion of saline of IL-1ra. Five days later, the tissue protein content and rate of protein synthesis were measured. IL-1ra did not significantly alter hepatic protein metabolism in septic or control animals. In kidney, the protein content and rate of protein synthesis were both decreased by sepsis and significantly ameliorated by the infusion of IL-1ra. Sepsis decreased the rate of protein synthesis in the small intestine. IL-1ra increased intestinal protein synthesis in both control and septic animals; however, the effects were localized to the seromuscular layer. The preservation of muscle protein by IL-1ra in sepsis did not adversely affect protein synthesis in any of the visceral tissues examined. IL-1 appears to mediate the sepsis-induced changes in protein synthesis in kidney and small intestine but not in liver or spleen. Protein synthesis in each visceral organ responds differently to the septic insult and modulation of IL-1 bioactivity.

Measurement of protein turnover in the small intestine of lambs. 1. Development of an experimental model

1997 ◽  
Vol 128 (2) ◽  
pp. 217-231
Author(s):  
S. A. NEUTZE ◽  
J. M. GOODEN ◽  
V. H. ODDY
Keyword(s):  
Protein Synthesis ◽  
Small Intestine ◽  
Experimental Model ◽  
Energy Use ◽  
Specific Radioactivity ◽  
Indirect Evidence ◽  
Energy Utilization ◽  
Protein Pool ◽  
Fractional Synthesis ◽  
The Mean

The objective of this study was to develop an experimental model to measure both fractional and absolute rates of protein synthesis in the small intestine of lambs. Six male castrate lambs (∼6 months old, mean liveweight 26 kg) were offered, via continuous feeders, 900 g/day lucerne chaff. They 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) (441±33·8 μCi into the abomasum) and L-[U-14C]phenylalanine (43·9±4·08 μCi into the jugular) were also infused during the last 8 h. Blood from the CMV and FA was sampled during isotope infusions. At the end of infusions, lambs were killed and tissue and digesta samples removed from four sites along the small intestine (SI). 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. The total SI protein pool was 84 (±1·7) g and fractional gain rate was 7·5 (±5·5)% per day. Mean protein synthesis and fractional synthesis rates (FSR) were calculated from the mean retention of 14C and 3H in SI tissue. FSR tended to increase caudally along the SI (although P > 0·05). The choice of free Phe pool for estimating precursor specific radioactivity (SRA) for protein synthesis had a significant effect on FSR. Assuming that tissue free Phe SRA represented precursor SRA gave a mean FSR of 129 (±24)% per day. Corresponding estimates for free Phe SRA in the FA and CMV were 20 (±1·8) and 30 (±3·1)% per day respectively. 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. Advantages of the present experimental model compared to other methods included (i) measurements of both protein synthesis and gain, and hence, all components of turnover, (ii) measurement of absolute as well as fractional rates of synthesis and gain, (iii) inclusion of proteins which are synthesised and exported, and (iv) concurrent measurement of protein synthesis and energy utilization by the small intestine.

scholarly journals Specific post-absorptive and post-prandial responses of protein synthesis to dietary protein levels in muscle, liver and small intestine

1998 ◽  
Vol 38 (2) ◽  
pp. 188-189
Author(s):  
M. A. Arnal ◽  
M. C. Valluy ◽  
P. Capitan ◽  
G. Bayle ◽  
P. Patureau Mirand
Keyword(s):  
Protein Synthesis ◽  
Small Intestine ◽  
Dietary Protein ◽  
Protein Levels

SEPSIS INCREASES PUTRESCINE CONCENTRATION AND PROTEIN SYNTHESIS IN MUCOSA OF SMALL INTESTINE IN RATS

Shock ◽  
1996 ◽  
Vol 5 (5) ◽  
pp. 333-340 ◽  
Author(s):  
Yoshifumi Noguchi ◽  
Tory Meyer ◽  
Greg Tiao ◽  
Josef E. Fischer ◽  
Per-Olof Hasselgren
Keyword(s):  
Protein Synthesis ◽  
Small Intestine

Deprivation of dietary nucleotides decreases protein synthesis in the liver and small intestine in rats

1996 ◽  
Vol 110 (6) ◽  
pp. 1760-1769 ◽  
Author(s):  
AT Lopez-Navarro ◽  
MA Ortega ◽  
J Peragon ◽  
JD Bueno ◽  
A Gil ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Small Intestine ◽  
Dietary Nucleotides

scholarly journals Protein synthesis of muscle fractions from the small intestine in alcohol fed rats.

Gut ◽  
1990 ◽  
Vol 31 (3) ◽  
pp. 305-310 ◽  
Author(s):  
V R Preedy ◽  
T J Peters
Keyword(s):  
Protein Synthesis ◽  
Small Intestine

scholarly journals The estimation of digestible protein in the small intestine of ruminants. The French system.

2018 ◽  
Vol 51 (2) ◽  
pp. 100
Author(s):  
P. FLOROU-PANERI (Π. ΦΛΩΡΟΥ - ΠΑΝΕΡΗ)
Keyword(s):  
Protein Synthesis ◽  
Small Intestine ◽  
Dietary Protein ◽  
Microbial Protein ◽  
Protein Nitrogen ◽  
Protein Requirements ◽  
Microbial Protein Synthesis ◽  
Digestible Protein ◽  
Protein Degradability

The ruminants, as all animals, need to obtain a certain amount of dietary protein to satisfy their requirements in nitrogen. Until 1978, the system of digestible protein was employed in France to estimate both the nitrogen requirements of ruminants for their maintenance and/or production and the protein value of feedstuffs. This system, however, presents considerable disadvantages since it cannot distinguish the protein nitrogen from the non protein nitrogen. Moreover, this system does not take into account the microbial protein synthesis and the protein degradability in the rumen. It was for these reasons that French researchers start using from 1978 the system of digestible protein in the small intestine, i.e. the system P.D.I. for the estimation of the protein requirements of ruminants and the protein value of feedstuffs.

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