scholarly journals Metabolic and Physiological Roles of Branched-Chain Amino Acids

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Md. Monirujjaman ◽  
Afroza Ferdouse
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Cell Function ◽  
Immune Cell ◽  
Muscle Protein ◽  
Glycogen Synthesis ◽  
Well Being ◽  
Protein Supplementation ◽  
Acid Oxidation ◽  
Protein Loss

Branch chain amino acids (BCAAs) have unique properties with diverse physiological and metabolic roles. They have functions other than simple nutrition. Different diseases including metabolic disease lead to protein loss, especially muscle protein. Supplementation of BCAAs promotes protein synthesis and reduces break down, as well as improving disease conditions. They are important regulators of mTOR signaling pathway and regulate protein synthesis as well as protein turnover. BCAAs facilitate glucose uptake by liver and SK muscle and also enhance glycogen synthesis. Oxidation of BCAAs seems to be beneficial for metabolic health as their catabolism increases fatty acid oxidation and reduces risk of obesity. BCAAs are also important in immunity, brain function, and other physiological aspects of well-being. All three BCAAs are absolutely required for lymphocyte growth and proliferation. They are also important for proper immune cell function. BCAAs may influence brain protein synthesis, and production of energy and may influence synthesis of different neurotransmitters. BCAAs can be used therapeutically and future studies may be directed to investigating the diverse effects of BCAAs in different tissues and their signaling pathways.

Hemodialysis stimulates muscle and whole body protein loss and alters substrate oxidation

2002 ◽  
Vol 282 (1) ◽  
pp. E107-E116 ◽  
Author(s):  
T. Alp Ikizler ◽  
Lara B. Pupim ◽  
John R. Brouillette ◽  
Deanna K. Levenhagen ◽  
Kali Farmer ◽  
...  
Keyword(s):  
Amino Acids ◽  
Muscle Protein ◽  
Substrate Oxidation ◽  
Whole Body ◽  
Constant Infusion ◽  
Acid Oxidation ◽  
Protein Breakdown ◽  
Protein Loss ◽  
Body Protein ◽  
Protein Calorie Malnutrition

The hemodialysis (HD) procedure has been implicated as a potential catabolic factor predisposing the chronic HD (CHD) patients to protein calorie malnutrition. To assess the potential effects of HD on protein and energy metabolism, we studied 11 CHD patients 2 h before, during, and 2 h after HD by use of primed constant infusion of l-[1-13C]leucine andl-[ ring-2H5]phenylalanine. Our results showed that HD led to increased whole body (10%) and muscle protein (133%) proteolysis. Simultaneously, whole body protein synthesis did not change, and forearm synthesis increased (120%). The net result was increased net whole body protein loss (96%) and net forearm protein loss (164%). During the 2-h post-HD period, the muscle protein breakdown trended toward baseline, whereas whole body protein breakdown increased further. Substrate oxidation during the post-HD was significantly altered, with diminished carbohydrate and accelerated lipid and amino acid oxidation. These data demonstrate that hemodialysis is an overall catabolic event, decreasing the circulating amino acids, accelerating rates of whole body and muscle proteolysis, stimulating muscle release of amino acids, and elevating net whole body and muscle protein loss.

Protein depletion and replenishment in mice: different roles of muscle and liver

1997 ◽  
Vol 273 (6) ◽  
pp. E1158-E1167 ◽  
Author(s):  
Oscar A. Scornik ◽  
Scott K. Howell ◽  
Violeta Botbol
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Protein Synthesis ◽  
Gastrointestinal Tract ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Acute Effects ◽  
Protein Loss ◽  
Protein Free Diet ◽  
Exogenous Supply

Fully grown male CD-1 mice, fed a protein-free diet for 3 days, received 1 g of starch with or without 300 mg casein by intragastric intubation. We surveyed the acute effects of these nutrients on protein synthesis in all tissues (by extrapolating to infinity the incorporation of radioactive leucine after its injection in massive doses) and protein degradation in skeletal muscle and liver (by the accumulation of bestatin-induced peptide intermediates). Muscle proteolysis was the major source of N during depletion. Compared with postabsorptive animals, starch suppressed muscle protein loss (synthesis +21%, degradation −24%, P < 0.01) and stimulated hepatic proteolysis (degradation +28%, P < 0.01). Addition of casein to the starch was anabolic in liver (synthesis +41%, degradation −33%, P < 0.01), gastrointestinal tract, pancreas, and skin (synthesis +38, +69 and +38%, respectively, P < 0.01) but had no effect on muscle. Protein turnover proved uniquely sensitive to the dietary supply of carbohydrates in muscle and to the endogenous or exogenous supply of amino acids in liver.

Nutritional Strategies to Promote Postexercise Recovery

2010 ◽  
Vol 20 (6) ◽  
pp. 515-532 ◽  
Author(s):  
Milou Beelen ◽  
Louise M. Burke ◽  
Martin J. Gibala ◽  
Luc J.C. van Loon
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Muscle Glycogen ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Glycogen Synthesis ◽  
Essential Amino Acids ◽  
Intact Protein ◽  
Postexercise Recovery ◽  
Glycogen Repletion

During postexercise recovery, optimal nutritional intake is important to replenish endogenous substrate stores and to facilitate muscle-damage repair and reconditioning. After exhaustive endurance-type exercise, muscle glycogen repletion forms the most important factor determining the time needed to recover. Postexercise carbohydrate (CHO) ingestion has been well established as the most important determinant of muscle glycogen synthesis. Coingestion of protein and/or amino acids does not seem to further increase muscle glycogensynthesis rates when CHO intake exceeds 1.2 g · kg−1 · hr−1. However, from a practical point of view it is not always feasible to ingest such large amounts of CHO. The combined ingestion of a small amount of protein (0.2–0.4 g · (0.2−0.4 g · kg−1 · hr−1) with less CHO (0.8 g · kg−1 · hr−1) stimulates endogenous insulin release and results in similar muscle glycogen-repletion rates as the ingestion of 1.2 g · kg−1 · hr−1 CHO. Furthermore, postexercise protein and/or amino acid administration is warranted to stimulate muscle protein synthesis, inhibit protein breakdown, and allow net muscle protein accretion. The consumption of ~20 g intact protein, or an equivalent of ~9 g essential amino acids, has been reported to maximize muscle protein-synthesis rates during the first hours of postexercise recovery. Ingestion of such small amounts of dietary protein 5 or 6 times daily might support maximal muscle protein-synthesis rates throughout the day. Consuming CHO and protein during the early phases of recovery has been shown to positively affect subsequent exercise performance and could be of specific benefit for athletes involved in multiple training or competition sessions on the same or consecutive days.

scholarly journals Cellular and metabolic mechanisms of nutrient actions in immune function

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Philip Newsholme
Keyword(s):  
Amino Acids ◽  
Fatty Acids ◽  
Vitamin D ◽  
Immune System ◽  
Cell Function ◽  
Immune Cell ◽  
Cell Structure ◽  
Nutritional Intervention ◽  
Immune Cell Function ◽  
And Function

AbstractVarious nutrients can change cell structure, cellular metabolism, and cell function which is particularly important for cells of the immune system as nutrient availability is associated with the activation and function of diverse immune subsets. The most important nutrients for immune cell function and fate appear to be glucose, amino acids, fatty acids, and vitamin D. This perspective will describe recently published information describing the mechanism of action of prominent nutritional intervention agents where evidence exists as to their action and potency.

scholarly journals Exercise, Amino Acids, and Aging in the Control of Human Muscle Protein Synthesis

2011 ◽  
Vol 43 (12) ◽  
pp. 2249-2258 ◽  
Author(s):  
DILLON K. WALKER ◽  
JARED M. DICKINSON ◽  
KYLE L. TIMMERMAN ◽  
MICAH J. DRUMMOND ◽  
PAUL T. REIDY ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Human Muscle

Growth hormone acutely stimulates forearm muscle protein synthesis in normal humans

1991 ◽  
Vol 260 (3) ◽  
pp. E499-E504 ◽  
Author(s):  
D. A. Fryburg ◽  
R. A. Gelfand ◽  
E. J. Barrett
Keyword(s):  
Skeletal Muscle ◽  
Amino Acids ◽  
Growth Hormone ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Skeletal Muscle Protein ◽  
Skeletal Muscle Protein Synthesis ◽  
Igf I ◽  
Normal Humans

The short-term effects of growth hormone (GH) on skeletal muscle protein synthesis and degradation in normal humans are unknown. We studied seven postabsorptive healthy men (age 18-23 yr) who received GH (0.014 micrograms.kg-1.min-1) via intrabrachial artery infusion for 6 h. The effects of GH on forearm amino acid and glucose balances and on forearm amino acid kinetics [( 3H]Phe and [14C]Leu) were determined after 3 and 6 h of the GH infusion. Forearm deep vein GH rose to 35 +/- 6 ng/ml in response to GH, whereas systemic levels of GH, insulin, and insulin-like growth factor I (IGF-I) were unchanged. Forearm glucose uptake did not change during the study. After 6 h, GH suppressed forearm net release (3 vs. 6 h) of Phe (P less than 0.05), Leu (P less than 0.01), total branched-chain amino acids (P less than 0.025), and essential neutral amino acids (0.05 less than P less than 0.1). The effect on the net balance of Phe and Leu was due to an increase in the tissue uptake for Phe (71%, P less than 0.05) and Leu (37%, P less than 0.005) in the absence of any significant change in release of Phe or Leu from tissue. In the absence of any change in systemic GH, IGF-I, or insulin, these findings suggest that locally infused GH stimulates skeletal muscle protein synthesis. These findings have important physiological implications for both the role of daily GH pulses and the mechanisms through which GH can promote protein anabolism.

Effects of glucose, pyruvate, lactate, and amino acids on muscle protein synthesis

1982 ◽  
Vol 242 (3) ◽  
pp. E184-E192 ◽  
Author(s):  
M. P. Hedden ◽  
M. G. Buse
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Creatine Phosphate ◽  
Serum Amino Acids ◽  
14Co2 Production ◽  
Beta Hydroxybutyrate ◽  
Free Media ◽  
Effect Of Glucose

Protein synthesis was measured in rat diaphragms incubated with serum amino acids + 0.35 mM L-[2,6-3H]tyrosine and different energy-yielding substrates. Muscles incubated with 5.5 mM glucose (with or without actinomycin D) synthesized more protein than those incubated with 11 mM pyruvate or 11 mM lactate. Tissue ATP decreased during incubation with lactate, but pyruvate maintained ATP, ADP, and creatine phosphate as well as glucose. Glucose 6-phosphate decreased in muscles incubated in glucose-free media. 14CO2 production from substrates was [1-14C]pyruvate greater than [1-14C]lactate greater than [3,4-14C]glucose. Intracellular lactate/pyruvate was measured to assess cytoplasmic free NADH/NAD+; the effect of different media on these ratios was lactate greater than glucose = lactate + pyruvate greater than pyruvate + glucose greater than pyruvate. Lactate + pyruvate (8.8 + 2.2 mM) supported protein synthesis better than pyruvate and as well as glucose. Adding glucose to pyruvate accelerated protein synthesis and increased NADH/NAD+. Iodoacetate (0.1 mM) inhibited glycolytic NAD reduction and abolished the stimulatory effect of glucose on protein synthesis in the presence of pyruvate. Supplementation of pyruvate media with 1 mM leucine or isoleucine stimulated protein synthesis, but beta-hydroxybutyrate, malate, alpha-ketoisocaproate, and all other amino acids were ineffective. The cytoplasmic redox potential may act as a translational modulator of protein synthesis in skeletal muscle.

An abundant supply of amino acids enhances the metabolic effect of exercise on muscle protein

1997 ◽  
Vol 273 (1) ◽  
pp. E122-E129 ◽  
Author(s):  
G. Biolo ◽  
K. D. Tipton ◽  
S. Klein ◽  
R. R. Wolfe
Keyword(s):  
Amino Acids ◽  
Blood Flow ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Protein Kinetics ◽  
Amino Acid Infusion

Six normal untrained men were studied during the intravenous infusion of a balanced amino acid mixture (approximately 0.15 g.kg-1.h-1 for 3 h) at rest and after a leg resistance exercise routine to test the influence of exercise on the regulation of muscle protein kinetics by hyperaminoacidemia. Leg muscle protein kinetics and transport of selected amino acids (alanine, phenylalanine, leucine, and lysine) were isotopically determined using a model based on arteriovenous blood samples and muscle biopsy. The intravenous amino acid infusion resulted in comparable increases in arterial amino acid concentrations at rest and after exercise, whereas leg blood flow was 64 +/- 5% greater after exercise than at rest. During hyperaminoacidemia, the increases in amino acid transport above basal were 30-100% greater after exercise than at rest. Increases in muscle protein synthesis were also greater after exercise than at rest (291 +/- 42% vs. 141 +/- 45%). Muscle protein breakdown was not significantly affected by hyperminoacidemia either at rest or after exercise. We conclude that the stimulatory effect of exogenous amino acids on muscle protein synthesis is enhanced by prior exercise, perhaps in part because of enhanced blood flow. Our results imply that protein intake immediately after exercise may be more anabolic than when ingested at some later time.

Sign in / Sign up

Export Citation Format

Share Document