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.

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.

A comparison of changes in whole body and skin amino acid metabolism of sheep in response to 24 h continuous infusions of variants of insulin-like growth factor 1

1997 ◽  
Vol 77 (4) ◽  
pp. 695-706 ◽  
Author(s):  
G. E. Lobley ◽  
J. Lee ◽  
J. Hocking Edwards ◽  
P. M. Harris
Keyword(s):  
Blood Flow ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Growth Factor ◽  
Skin Blood Flow ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Whole Body ◽  
Insulin Like Growth Factor ◽  
Key Words Insulin

Because of the economic significance of wool to many sheep production systems, attempts to partition amino acids towards skin and wool protein synthesis have included both nutritional and hormonal methods of manipulation. A variant of insulin-like growth factor 1 (IGF-1) has previously been shown to transiently increase protein synthesis in the skin of sheep and the current study extended that work by comparing the effects of a 24 h, close-arterial, skin infusion of IGF-1, in the form of either recombinant human (rhIGF-1) or an extended variant (LR3IGF-1), on both whole body and skin amino acid metabolism adult, castrated Romney sheep, with three animals allocated to each treatment. There were no differences in food intake between the two treatment groups. The plasma concentration of immunoreactive IGF-1 of sheep infused with rhIGF-1 increased (P < 0.01) with time of administration, but decreased (P < 0.05) after 24 h of LR3IGF-1 infusion. Administration of both IGF-1 variants caused a substantial and sustained decrease in arterial insulin to less than 50% (P < 0.05) of pre-infusion values, while arterial plasma glucose concentrations were only reduced by 7%. Alterations in whole body and skin protein metabolism were assessed from continuous infusions of mixed [U-13C] AA, [2,6 ring 3H]phenylalanine and [35S]cysteine. Within 4 h both AA concentrations and whole body plasma ILR of essential and non-essential AA were decreased (P < 0.05 for seven AA) by IGF-1 infusions. Both IGF1 variants caused acute increases (P < 0.05) in skin blood flow and, for 13 of the 15 AA measured, isotopic transfers (range 50–220%; P < 0.05 for cysteine and tyrosine), which probably reflect increased protein synthesis. By 24 h skin blood flow, AA uptake and protein synthesis had returned to pre-infusion values. Strategies based on exogenous application, or enhanced endogenous production, of IGF-1 are unlikely, therefore, to produce persistent anabolic responses. Key words: Insulin-like growth factor 1, skin, sheep, protein synthesis

scholarly journals Rates of protein synthesis in skin and bone, and their importance in the assessment of protein degradation in the perfused rat hemicorpus

1981 ◽  
Vol 194 (1) ◽  
pp. 373-376 ◽  
Author(s):  
V R Preedy ◽  
P J Garlick
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Degradation ◽  
Muscle Tissue ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Muscle Protein ◽  
Muscle Metabolism ◽  
Muscle Protein Degradation

The perfused rat hemicorpus preparation, which has frequently been used to study muscle metabolism, contains 39% by weight of non-muscle tissue such as skin and bone. Both the concentration of RNA and the incorporation of [U-14C]tyrosine into protein indicate that the non-muscle components are more active in protein synthesis than is muscle. These observations have important implications for studies of amino acid metabolism, and in particular for the measurement of muscle protein degradation in the hemicorpus.

Somatotropin increases protein balance by lowering body protein degradation in fed, growing pigs

2000 ◽  
Vol 278 (3) ◽  
pp. E477-E483 ◽  
Author(s):  
Rhonda C. Vann ◽  
Hanh V. Nguyen ◽  
Peter J. Reeds ◽  
Douglas G. Burrin ◽  
Marta L. Fiorotto ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Growing Pigs ◽  
Whole Body ◽  
Plasma Urea ◽  
Body Protein ◽  
Fed State ◽  
Protein Deposition ◽  
Leucine Oxidation ◽  
Urea Production

Somatotropin (ST) administration enhances protein deposition in well-nourished, growing animals. To determine whether the anabolic effect is due to an increase in protein synthesis or a decrease in proteolysis, pair-fed, weight-matched (∼20 kg) growing swine were treated with porcine ST (150 μg ⋅ kg− 1 ⋅ day− 1, n = 6) or diluent ( n = 6) for 7 days. Whole body leucine appearance (Ra), nonoxidative leucine disposal (NOLD), urea production, and leucine oxidation, as well as tissue protein synthesis (Ks), were determined in the fed steady state using primed continuous infusions of [13C]leucine, [13C]bicarbonate, and [15N2]urea. ST treatment increased the efficiency with which the diet was used for growth. ST treatment also increased plasma insulin-like growth factor I (+100%) and insulin (+125%) concentrations and decreased plasma urea nitrogen concentrations (−53%). ST-treated pigs had lower leucine Ra (−33%), leucine oxidation (−63%), and urea production (−70%). However, ST treatment altered neither NOLD nor Ks in the longissimus dorsi, semitendinosus, or gastrocnemius muscles, liver, or jejunum. The results suggest that in the fed state, ST treatment of growing swine increases protein deposition primarily through a suppression of protein degradation and amino acid catabolism rather than a stimulation of protein synthesis.

scholarly journals Interactive effects of aging and aerobic capacity on energy metabolism–related metabolites of serum, skeletal muscle, and white adipose tissue

GeroScience ◽  
2021 ◽  
Author(s):  
Haihui Zhuang ◽  
Sira Karvinen ◽  
Timo Törmäkangas ◽  
Xiaobo Zhang ◽  
Xiaowei Ojanen ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Amino Acid ◽  
White Adipose Tissue ◽  
Aerobic Capacity ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Disease Risk ◽  
Whole Body ◽  
Whole Body Metabolism

AbstractAerobic capacity is a strong predictor of longevity. With aging, aerobic capacity decreases concomitantly with changes in whole body metabolism leading to increased disease risk. To address the role of aerobic capacity, aging, and their interaction on metabolism, we utilized rat models selectively bred for low and high intrinsic aerobic capacity (LCRs/HCRs) and compared the metabolomics of serum, muscle, and white adipose tissue (WAT) at two time points: Young rats were sacrificed at 9 months of age, and old rats were sacrificed at 21 months of age. Targeted and semi-quantitative metabolomics analysis was performed on the ultra-pressure liquid chromatography tandem mass spectrometry (UPLC-MS) platform. The effects of aerobic capacity, aging, and their interaction were studied via regression analysis. Our results showed that high aerobic capacity is associated with an accumulation of isovalerylcarnitine in muscle and serum at rest, which is likely due to more efficient leucine catabolism in muscle. With aging, several amino acids were downregulated in muscle, indicating more efficient amino acid metabolism, whereas in WAT less efficient amino acid metabolism and decreased mitochondrial β-oxidation were observed. Our results further revealed that high aerobic capacity and aging interactively affect lipid metabolism in muscle and WAT, possibly combating unfavorable aging-related changes in whole body metabolism. Our results highlight the significant role of WAT metabolism for healthy aging.

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 Effect of long-term refeeding on protein metabolism in patients with cirrhosis of the liver

1997 ◽  
Vol 77 (2) ◽  
pp. 197-212 ◽  
Author(s):  
Jens Kondrup ◽  
Klaus Nielsen ◽  
Anders Juul
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Protein Degradation ◽  
Protein Metabolism ◽  
Cirrhosis Of The Liver ◽  
N Balance ◽  
Whole Body ◽  
Protein Requirement ◽  
Protein Utilization ◽  
Igf I

Patients with cirrhosis of the liver require an increased amount of protein to achieve N balance. However, the utilization of protein with increased protein intake, i.e. the slope from regression analysis of N balance v. intake, is highly efficient (Nielsen et al. 1995). In the present study, protein requirement and protein utilization were investigated further by measuring protein synthesis and degradation. In two separate studies, five or six patients with cirrhosis of the liver were refed on a balanced diet for an average of 2 or 4 weeks. Protein and energy intakes were doubled in both studies. Initial and final whole-body protein metabolism was measured in the fed state by primed continous [15N]glycine infusion. Refeeding caused a statistically significant increase of about 30% in protein synthesis in both studies while protein degradation was only slightly affected. The increase in protein synthesis was associated with significant increases in plasma concentrations of total amino acids (25%), leucine (58%), isoleucine (82%), valine (72%), proline (48%) and triiodothyronine (27%) while insulin, growth hormone, insulin-like growth factor (IGF)-I and IGF-binding protein-3 were not changed significantly. The results indicate that the efficient protein utilization is due to increased protein synthesis, rather than decreased protein degradation, and suggest that increases in plasma amino acids may be responsible for the increased protein synthesis. A comparison of the patients who had a normal protein requirement with the patients who had an increased protein requirement suggests that the increased protein requirement is due to a primary increase in protein degradation. It is speculated that this is due to low levels of IGF-I secondary to impaired liver function, since initial plasma concentration of IGF-I was about 25% of control values and remained low during refeeding.

Somatotropin increases protein balance independent of insulin's effects on protein metabolism in growing pigs

2000 ◽  
Vol 279 (1) ◽  
pp. E1-E10 ◽  
Author(s):  
Rhonda C. Vann ◽  
Hanh V. Nguyen ◽  
Peter J. Reeds ◽  
Norman C. Steele ◽  
Daniel R. Deaver ◽  
...  
Keyword(s):  
Amino Acid ◽  
Protein Metabolism ◽  
Growing Pigs ◽  
Whole Body ◽  
Metabolic Responses ◽  
Glucose Disposal ◽  
Blood Levels ◽  
Protein Balance ◽  
Protein Deposition ◽  
Leucine Oxidation

Somatotropin (ST) administration enhances protein deposition and elicits profound metabolic responses, including hyperinsulinemia. To determine whether the anabolic effect of ST is due to hyperinsulinemia, pair-fed weight-matched growing swine were treated with porcine ST (150 μg · kg body wt−1 · day−1) or diluent for 7 days ( n = 6/group, ∼20 kg). Then pancreatic glucose-amino acid clamps were performed after an overnight fast. The objective was to reproduce the insulin levels of 1) fasted control and ST pigs (basal insulin, 5 μU/ml), 2) fed control pigs (low insulin, 20 μU/ml), and 3) fed ST pigs (high insulin, 50 μU/ml). Amino acid and glucose disposal rates were determined from the infusion rates necessary to maintain preclamp blood levels of these substrates. Whole body nonoxidative leucine disposal (NOLD), leucine appearance (Ra), and leucine oxidation were determined with primed, continuous infusions of [13C]leucine and [14C]bicarbonate. ST treatment was associated with higher NOLD and protein balance and lower leucine oxidation and amino acid and glucose disposals. Insulin lowered Ra and increased leucine oxidation, protein balance, and amino acid and glucose disposals. These effects of insulin were suppressed by ST treatment; however, the protein balance remained higher in ST pigs. The results show that ST treatment inhibits insulin's effects on protein metabolism and indicate that the stimulation of protein deposition by ST treatment is not mediated by insulin. Comparison of the protein metabolic responses to ST treatment during the basal fasting period with those in the fully fed state from a previous study suggests that the mechanism by which ST treatment enhances protein deposition is influenced by feeding status.

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.

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