Influence of branched-chain amino acids and branched-chain keto acids on protein synthesis in isolated hepatocytes

Hepatology ◽  
1987 ◽  
Vol 7 (2) ◽  
pp. 324-329 ◽  
Author(s):  
Wolfgang Base ◽  
Carl Barsigian ◽  
Alisa Schaeffer ◽  
Ellen Shaw ◽  
Jose Martinez ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Isolated Hepatocytes ◽  
Branched Chain Amino Acids ◽  
Keto Acids ◽  
Branched Chain ◽  
Branched Chain Keto Acids

Transamination of branched-chain keto acids by isolated perfused rat kidney.

1978 ◽  
Vol 235 (1) ◽  
pp. E47
Author(s):  
W E Mitch ◽  
W Chan
Keyword(s):  
Amino Acids ◽  
Rat Kidney ◽  
Branched Chain Amino Acids ◽  
Keto Acid ◽  
Branched Chain Amino Acid ◽  
Keto Acids ◽  
Perfused Rat Kidney ◽  
Branched Chain ◽  
Branched Chain Keto Acids ◽  
Isolated Rat

Isolated rat kidney perfused without substrate released serine, glycine, and taurine, and substantially smaller amounts of other amino acids. When branched-chain keto acids were added, the corresponding amino acids were released at rates amounting to 15-25% of keto acid disappearance. Perfusion with 2 mM alpha-keto-isovalerate or alpha-keto-beta-methylvalerate caused an increased glucose release amounting to 18-23% of keto acid disappearance. The activity of branched-chain amino acid transferase (BATase) was significantly stimulated by perfusion with the analogue of leucine, but not by perfusion with alpha-ketoglutarate, the analogues of valine or isoleucine, or with leucine itself. These findings document that the kidney converts branched-chain keto acids in part to the corresponding amino acids and suggest that the keto analogue of leucine may be involved in the control of renal BATase activity, thereby indirectly regulating the metabolism of branched-chain amino acids.

scholarly journals Branched-Chain Amino Acids and Branched-Chain Keto Acids in Hyperammonemic States: Metabolism and as Supplements

Metabolites ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 324 ◽  
Author(s):  
Milan Holeček
Keyword(s):  
Amino Acids ◽  
Branched Chain Amino Acids ◽  
Muscle Performance ◽  
Strenuous Exercise ◽  
Protein Balance ◽  
Keto Acids ◽  
Amino Acid Imbalance ◽  
Branched Chain ◽  
Cycle Disorders ◽  
Branched Chain Keto Acids

In hyperammonemic states, such as liver cirrhosis, urea cycle disorders, and strenuous exercise, the catabolism of branched-chain amino acids (BCAAs; leucine, isoleucine, and valine) is activated and BCAA concentrations decrease. In these conditions, BCAAs are recommended to improve mental functions, protein balance, and muscle performance. However, clinical trials have not demonstrated significant benefits of BCAA-containing supplements. It is hypothesized that, under hyperammonemic conditions, enhanced glutamine availability and decreased BCAA levels facilitate the amination of branched-chain keto acids (BCKAs; α-ketoisocaproate, α-keto-β-methylvalerate, and α-ketoisovalerate) to the corresponding BCAAs, and that BCKA supplementation may offer advantages over BCAAs. Studies examining the effects of ketoanalogues of amino acids have provided proof that subjects with hyperammonemia can effectively synthesize BCAAs from BCKAs. Unfortunately, the benefits of BCKA administration have not been clearly confirmed. The shortcoming of most reports is the use of mixtures intended for patients with renal insufficiency, which might be detrimental for patients with liver injury. It is concluded that (i) BCKA administration may decrease ammonia production, attenuate cataplerosis, correct amino acid imbalance, and improve protein balance and (ii) studies specifically investigating the effects of BCKA, without the interference of other ketoanalogues, are needed to complete the information essential for decisions regarding their suitability in hyperammonemic conditions.

Abstract MP125: Branched-chain Keto Acids, Not Branched-chain Amino Acids, Impairs Cardiac Insulin Sensitivity by Disrupting Insulin Signaling in the Mitochondria

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Qutuba Karwi ◽  
Golam Mezbah Uddin ◽  
Cory S Wagg ◽  
Gary D Lopaschuk
Keyword(s):  
Insulin Resistance ◽  
Amino Acids ◽  
Insulin Sensitivity ◽  
Glucose Oxidation ◽  
Branched Chain Amino Acids ◽  
Mitochondrial Translocation ◽  
Oxidation Rates ◽  
Keto Acids ◽  
Branched Chain ◽  
Branched Chain Keto Acids

Alterations in branched-chain amino acids (BCAA) oxidation have been linked to the development of cardiac insulin resistance and its negative impact on cardiac function. However, it is not clear if these detrimental effects are due to the accumulation of BCAAs or branched-chain keto acids (BCKAs). It is also unknown how impaired BCAAs oxidation mediates cardiac insulin resistance. To examine this, we specifically deleted mitochondrial branched-chain aminotransferase (BCATm) in the heart to selectively increase in BCAAs and decrease in BCKAs in the heart. BCATm -/- mice had normal cardiac function compared to their wildtype littermates (WT Cre+/+ ). However, there was a significant increase in insulin-stimulated cardiac glucose oxidation rates in BCATm -/- mice, independent of any changes in glucose uptake or glycolytic rates. This enhancement in cardiac insulin sensitivity was associated with an increase in the phosphorylation of Akt and activation of pyruvate dehydrogenase (PDH), the rate-limiting enzyme of glucose oxidation. To determine the impact of reversing these events, we examined the effects of increasing cardiac BCKAs on cardiac insulin sensitivity. We perfused isolated working mice hearts with high levels of BCKAs (α;-keto-isocaproate 80 μM, α;-keto-β;-methylvalorate 100μM, α;-keto-isovalorate 70 μM), levels that can be seen during diabetes and obesity. The BCKAs completely blunted insulin-stimulated glucose oxidation rates. We also found that BCKAs abolished insulin-stimulated mitochondrial translocation of Akt, an effect which was associated with PDH deactivation. We conclude that the accumulation of BCKAs, and not BCAAs, is a major contributor to cardiac insulin resistance via abrogating mitochondrial translocation of Akt.

scholarly journals Amino acid infusion increases the sensitivity of muscle protein synthesis in vivo to insulin. Effect of branched-chain amino acids

1988 ◽  
Vol 254 (2) ◽  
pp. 579-584 ◽  
Author(s):  
P J Garlick ◽  
I Grant
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Branched Chain Amino Acids ◽  
Acid Infusion ◽  
Amino Acid Infusion ◽  
Branched Chain

Rates of muscle protein synthesis were measured in vivo in tissues of post-absorptive young rats that were given intravenous infusions of various combinations of insulin and amino acids. In the absence of amino acid infusion, there was a steady rise in muscle protein synthesis with plasma insulin concentration up to 158 mu units/ml, but when a complete amino acids mixtures was included maximal rates were obtained at 20 mu units/ml. The effect of the complete mixture could be reproduced by a mixture of essential amino acids or of branched-chain amino acids, but not by a non-essential mixture, alanine, methionine or glutamine. It is concluded that amino acids, particularly the branched-chain ones, increase the sensitivity of muscle protein synthesis to insulin.

Protein synthesis in human tumour and muscle is enhanced more by TPN than by solutions enriched with branched-chain amino acids

1990 ◽  
Vol 9 ◽  
pp. 21-22 ◽  
Author(s):  
M.A. McNurlan ◽  
S.D. Heys ◽  
K.G.M. Park ◽  
J. Broom ◽  
D. Brown ◽  
...  
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Branched Chain Amino Acids ◽  
Human Tumour ◽  
Branched Chain

scholarly journals Effect of endurance training and branched-chain amino acids on the signaling for muscle protein synthesis in CKD model rats fed a low-protein diet

2017 ◽  
Vol 313 (3) ◽  
pp. F805-F814 ◽  
Author(s):  
Takuya Yoshida ◽  
Sachika Kakizawa ◽  
Yuri Totsuka ◽  
Miho Sugimoto ◽  
Shinji Miura ◽  
...  
Keyword(s):  
Amino Acids ◽  
Renal Function ◽  
Protein Synthesis ◽  
Sham Group ◽  
Treadmill Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Branched Chain Amino Acids ◽  
Low Protein ◽  
Branched Chain

A low-protein diet (LPD) protects against the progression of renal injury in patients with chronic kidney disease (CKD). However, LPD may accelerate muscle wasting in these patients. Both exercise and branched-chain amino acids (BCAA) are known to increase muscle protein synthesis by activating the mammalian target of rapamycin (mTOR) pathway. The aim of this study was to investigate whether endurance exercise and BCAA play a role for increasing muscle protein synthesis in LPD-fed CKD (5/6 nephrectomized) rats. Both CKD and sham rats were pair-fed on LPD or LPD fortified with a BCAA diet (BD), and approximately one-half of the animals in each group was subjected to treadmill exercise (15 m/min, 1 h/day, 5 days/wk). After 7 wk, renal function was measured, and soleus muscles were collected to evaluate muscle protein synthesis. Renal function did not differ between LPD- and BD-fed CKD rats, and the treadmill exercise did not accelerate renal damage in either group. The treadmill exercise slightly increased the phosphorylation of p70s6 kinase, a marker of mTOR activity, in the soleus muscle of LPD-fed CKD rats compared with the sham group. Furthermore, BCAA supplementation of the LPD-fed, exercise-trained CKD rats restored the phosphorylation of p70s6 kinase to the same level observed in the sham group; however, the corresponding induced increase in muscle protein synthesis and muscle mass was marginal. These results indicate that the combination of treadmill exercise and BCAA stimulates cell signaling to promote muscle protein synthesis; however, the implications of this effect for muscle growth remain to be clarified.

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