Preliminary 'in vivo' measurements of protein and energy metabolism in the skin of sheep

1989 ◽  
Vol 40 (4) ◽  
pp. 879 ◽  
Author(s):  
PM Harris ◽  
DW Dellow ◽  
BR Sinclair
Keyword(s):  
Blood Flow ◽  
Protein Synthesis ◽  
Acid Metabolism ◽  
Significant Proportion ◽  
Whole Body ◽  
Oxygen Utilization ◽  
Body Protein ◽  
Discrete Area ◽  
Made In

An arterio-venous preparation was developed which allowed infusion into, and/or sampling from, branches of the deep circumflex iliac artery and vein supplying and draining a discrete area of skin on the abdominal flank of Romney sheep.Measurements of blood flow (using dye dilution techniques), utilization or output of energy metabolites (oxygen, glucose, lactate and acetate) and amino acid metabolism were made in relation to whole body protein and energy metabolism.Measurements on the patch suggested that blood flow to the total skin was about 6% of cardiac output but that only 1-2% of whole body oxygen utilization occurred in the skin. This was partly accounted for by a significant proportion of glucose uptake (1.15 g day-1) being anaerobically oxidized to lactate (0.41 g day-1). Measurements of protein synthesis in the patch showed that between 10 and 16% of whole body protein synthesis occurs in the skin.Results from the preparation demonstrate that it is a useful procedure to study metabolism in a defined patch of skin in the intact animal.

Enhancement of tumor proteolysis by TNF-alpha: correlation of in vivo isotope estimates with growth

1991 ◽  
Vol 261 (1) ◽  
pp. R106-R116
Author(s):  
N. W. Istfan ◽  
P. R. Ling ◽  
G. L. Blackburn ◽  
B. R. Bistrian
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Whole Body ◽  
Independent Effect ◽  
Yoshida Sarcoma ◽  
Protein Breakdown ◽  
Body Protein ◽  
Breakdown Rates ◽  
Made In

To evaluate the accuracy of in vivo estimates of protein synthesis and breakdown, measurements of plasma and tissue leucine kinetics were made in rat tumor tissues at different conditions of growth by use of constant intravenous infusion of [14C]leucine. These measurements were made in Yoshida sarcoma tumors on days 10 and 13 after implantation, with and without tumor necrosis factor (TNF) infusion and on day 10 in Walker-256 carcinosarcoma. Expressed as micromoles of leucine per gram tissue, tumor protein breakdown increased (P less than 0.01) from 0.32 +/- 0.02 to 0.52 +/- 0.09 (SE) mumol/h, with progress of the Yoshida sarcoma tumor between days 10 and 13 after implantation. Similarly, TNF increased tumor proteolysis on day 10 (0.43 +/- 0.03 mumol.h-1.g-1, P less than 0.05 vs. day 10 control) but not on day 13 after implantation of the Yoshida tumor. Estimates of growth derived from the difference between protein synthesis and breakdown rates were not statistically different from those based on actual tumor volume changes in both tumor models. However, estimates of “whole body” protein metabolism (plasma leucine flux) were not affected either by tumor aging or by treatment with TNF. This study shows that in vivo estimates of tissue protein metabolism based on our [14C]leucine constant infusion model closely reflect the growth characteristic of that tissue. A cytotoxic perfusion-independent effect for intravenous TNF on growing tumor tissue is demonstrable as increased protein breakdown. Furthermore, the commonly used concept of whole body protein metabolism, derived solely from tracer dilution in plasma, is an oversimplification.

scholarly journals Comprehensive assessment of post-prandial protein handling by the application of intrinsically labelled protein in vivo in human subjects

2021 ◽  
pp. 1-9
Author(s):  
Jorn Trommelen ◽  
Andrew M. Holwerda ◽  
Philippe J. M. Pinckaers ◽  
Luc J. C. van Loon
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Stable Isotope ◽  
Dietary Protein ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Human Subjects ◽  
Whole Body ◽  
Body Protein

All human tissues are in a constant state of remodelling, regulated by the balance between tissue protein synthesis and breakdown rates. It has been well-established that protein ingestion stimulates skeletal muscle and whole-body protein synthesis. Stable isotope-labelled amino acid methodologies are commonly applied to assess the various aspects of protein metabolism in vivo in human subjects. However, to achieve a more comprehensive assessment of post-prandial protein handling in vivo in human subjects, intravenous stable isotope-labelled amino acid infusions can be combined with the ingestion of intrinsically labelled protein and the collection of blood and muscle tissue samples. The combined application of ingesting intrinsically labelled protein with continuous intravenous stable isotope-labelled amino acid infusion allows the simultaneous assessment of protein digestion and amino acid absorption kinetics (e.g. release of dietary protein-derived amino acids into the circulation), whole-body protein metabolism (whole-body protein synthesis, breakdown and oxidation rates and net protein balance) and skeletal muscle metabolism (muscle protein fractional synthesis rates and dietary protein-derived amino acid incorporation into muscle protein). The purpose of this review is to provide an overview of the various aspects of post-prandial protein handling and metabolism with a focus on insights obtained from studies that have applied intrinsically labelled protein under a variety of conditions in different populations.

scholarly journals Comparison of different techniques for estimating rates of protein synthesis in vivo in healthy and bacteraemic rats

1985 ◽  
Vol 226 (1) ◽  
pp. 37-42 ◽  
Author(s):  
J J Pomposelli ◽  
J D Palombo ◽  
K J Hamawy ◽  
B R Bistrian ◽  
G L Blackburn ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Rectus Muscle ◽  
Stochastic Modelling ◽  
Whole Body ◽  
Constant Infusion ◽  
Second Phase ◽  
Sprague Dawley ◽  
Body Protein ◽  
To Receive

Previous studies have reported that use of a flooding dose of radiolabelled amino acid is a more precise technique than the constant infusion of tracer quantities for determining rates of protein synthesis in rapidly turning-over tissues in the rat. However, there has been little direct investigation comparing different methods under comparable conditions. Initially, 12 healthy male Sprague-Dawley rats, weighing approx. 100 g, were randomized to receive either a bolus intravenous injection of 100 mumol of L-leucine (containing 30 microCi of [1-14C]leucine)/100 g body wt., or a continuous 2 h tracer infusion of [14C]leucine. In the second phase of the experiment, 12 additional rats were intravenously injected with 1 × 10(8) colony-forming units of Pseudomonas aeruginosa and 16 h later randomized to receive one of two infusions described above. Total protein synthesis as well as fractional synthesis rates were determined in liver, rectus muscle and whole body. Synthesis rates measured in liver, muscle and whole body were significantly higher in bacteraemic rats than in healthy rats. The flooding-dose methodology gave significantly higher estimates of protein synthesis in the liver, skeletal muscle and whole body than did the continuous-infusion method using direct measurement of the acid-soluble fraction from the respective tissue. Indirect estimates of whole-body protein synthesis based on plasma enrichments and stochastic modelling gave the lowest values.

Energy cost of whole-body protein synthesis measured in vivo in chicks

1988 ◽  
Vol 91 (4) ◽  
pp. 765-768 ◽  
Author(s):  
Yosuke Aoyagi ◽  
Iwao Tasaki ◽  
Jun-ichi Okumura ◽  
Tatsuo Muramatsu
Keyword(s):  
Protein Synthesis ◽  
Energy Cost ◽  
Whole Body ◽  
Body Protein

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.

Chloroquine reduces whole body proteolysis in humans

1994 ◽  
Vol 267 (1) ◽  
pp. E183-E186 ◽  
Author(s):  
P. De Feo ◽  
E. Volpi ◽  
P. Lucidi ◽  
G. Cruciani ◽  
F. Santeusanio ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Turnover ◽  
Plasma Concentrations ◽  
Whole Body ◽  
Body Protein ◽  
Leucine Kinetics ◽  
Lysosomal Proteolysis ◽  
Therapeutic Doses

The antimalaric drug chloroquine is a well known inhibitor of lysosomal proteolysis in vitro. The present study tests the hypothesis that therapeutic doses of the drug decrease proteolysis also in vivo in humans. Leucine kinetics were determined in 20 healthy volunteers given 12 and 1.5 h before the studies 250 and 500 mg, respectively, of chloroquine phosphate (n = 10) or similar tablets of placebo (n = 10). Chloroquine reduced the rates of leucine appearance, a measure of whole body proteolysis, from 2.45 +/- 0.08 to 2.19 +/- 0.08 mumol.kg-1.min-1 (P = 0.038) and those of nonoxidative leucine disposal, an estimate of whole body protein synthesis, from 2.16 +/- 0.08 to 1.95 +/- 0.06 mumol.kg-1.min-1 (P = 0.050). The drug resulted also in a marginally significant (P = 0.051) decrement in the plasma concentrations of glucose. The effects of chloroquine on protein turnover might be potentially useful in counteracting protein wasting complicating several catabolic diseases, whereas those on glucose metabolism can explain the sporadic occurrence of severe hypoglycemic episodes in malaria patients chronically treated with this drug.

Amino acid metabolism after intense exercise

1990 ◽  
Vol 258 (2) ◽  
pp. E249-E255 ◽  
Author(s):  
J. T. Devlin ◽  
I. Brodsky ◽  
A. Scrimgeour ◽  
S. Fuller ◽  
D. M. Bier
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Degradation ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Recovery Period ◽  
Whole Body ◽  
Protein Breakdown ◽  
Body Protein ◽  
Leucine Oxidation

We studied postexercise amino acid metabolism, in the whole body and across the forearm. Seven volunteers were infused with L-[alpha-15N]lysine and L-[1-13C]-leucine twice [one time during 3 h after cycle exercise (75% VO2max), and one time in the resting state]. Whole body protein breakdown was estimated from dilution of L-[alpha-15N]lysine and L-[1-13C]ketoisocaproic acid (KIC) enrichments in plasma. Leucine oxidation was calculated from 13CO2 enrichments in expired air. Whole body protein breakdown was not increased above resting levels during the recovery period. Leucine oxidation was decreased after exercise (postexercise 13 +/- 2.3 vs. resting 19 +/- 3.2 mumol.kg-1.h-1; P less than 0.02), while nonoxidative leucine disposal was increased (115 +/- 6.1 vs. 103 +/- 5.6 micrograms.kg-1.min-1; P less than 0.02). After exercise, forearm net lysine balance was unchanged (87 +/- 25 vs. 93 +/- 28 nmol.100 ml-1.min-1), but there were decreases in forearm muscle protein degradation (219 +/- 51 vs. 356 +/- 85 nmol.100 ml-1.min-1; P less than 0.05) and synthesis (132 +/- 41 vs. 255 +/- 69 nmol.100 ml-1.min-1; P less than 0.01). In conclusion, after exercise 1) whole body protein degradation is not increased, 2) leucine disposal is directed away from oxidative and toward nonoxidative pathways, 3) forearm protein synthesis is decreased. Postexercise increases in whole body protein synthesis occur in tissues other than nonexercised muscle.

scholarly journals A simple method for evaluating whole body protein synthesis in chick embryos in vivo.

1987 ◽  
Vol 24 (1) ◽  
pp. 39-43 ◽  
Author(s):  
Tatsuo MURAMATSU ◽  
Toshiyasu KATO ◽  
Jun-ichi OKUMURA ◽  
Iwao TASAKI
Keyword(s):  
Protein Synthesis ◽  
Whole Body ◽  
Chick Embryos ◽  
Simple Method ◽  
Body Protein

Somatotropin-induced protein anabolism in hindquarters and portal-drained viscera of growing pigs

2003 ◽  
Vol 284 (2) ◽  
pp. E302-E312 ◽  
Author(s):  
Jill A. Bush ◽  
Douglas G. Burrin ◽  
Agus Suryawan ◽  
Pamela M. J. O'Connor ◽  
Hanh V. Nguyen ◽  
...  
Keyword(s):  
Blood Flow ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Degradation ◽  
Protein Metabolism ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Growing Pigs ◽  
Whole Body ◽  
Fed State

To differentiate the effect of somatotropin (ST) treatment on protein metabolism in the hindquarter (HQ) and portal-drained viscera (PDV), growing swine ( n = 20) treated with ST (0 or 150 μg · kg−1 · day−1) for 7 days were infused intravenously with NaH13CO3 and [2H5]phenylalanine and enterally with [1-13C]phenylalanine while in the fed state. Arterial, portal venous, and vena cava whole blood samples, breath samples, and blood flow measurements were obtained for determination of tissue and whole body phenylalanine kinetics under steady-state conditions. In the fed state, ST treatment decreased whole body phenylalanine flux, oxidation, and protein degradation without altering protein synthesis, resulting in an improvement in whole body net protein balance. Blood flow to the HQ (+80%), but not to the PDV, was increased with ST treatment. In the HQ and PDV, ST increased phenylalanine uptake (+44 and +23%, respectively) and protein synthesis (+43 and +41%, respectively), with no effect on protein degradation. In ST-treated and control pigs, phenylalanine was oxidized in the PDV (34–43% of enteral and arterial sources) but not the HQ. In both treatment groups, dietary (40%) rather than arterial (10%) extraction of phenylalanine predominated in gut amino acid metabolism, whereas localized blood flow influenced HQ amino acid metabolism. The results indicate that ST increases protein anabolism in young, growing swine by increasing protein synthesis in the HQ and PDV, with no effect on protein degradation. Differing results between the whole body and the HQ and PDV suggest that the effect of ST treatment on protein metabolism is tissue specific.

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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