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       #Post#: 1445--------------------------------------------------
       Effects of Branched-Chain-Amino Acids, and Leucine
       By: Road2HardCoreIron Date: November 9, 2022, 6:32 pm
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       Effects of branched-chain-enriched amino acids and insulin on
       forearm leucine kinetics
       M Zanetti 1, R Barazzoni, E Kiwanuka, P Tessari
       Affiliations expand
       PMID: 10491344
       Abstract
       Although amino acid mixtures enriched in branched-chain amino
       acids (BCAA) and deficient in aromatic amino acids (AAA) are
       often used together with insulin and glucose in clinical
       nutrition, their physiological effects on muscle protein
       anabolism are not known. To this aim, we studied forearm leucine
       kinetics in post-absorptive volunteers, before and after the
       systemic infusion of BCAA-enriched, AAA-deficient amino acids
       along with insulin and the euglycaemic clamp. The results were
       compared with the effects of insulin infusion alone. A
       compartmental leucine forearm model was employed at steady
       state. Hyperaminoacidaemia with hyperinsulinaemia (to
       approximately 80-100 micro-units/ml) increased the leucine
       plasma concentration (+70%; P<0.001), inflow into the forearm
       cell (+150%; P<0.01), disposal into protein synthesis (+100%;
       P<0.01), net intracellular retention (P<0.01), net forearm
       balance (by approximately 6-fold; P<0.01) and net deamination to
       alpha-ketoisocaproate (4-methyl-2-oxopentanoate) (+9%; P<0.05).
       Leucine release from forearm proteolysis and outflow from the
       forearm cell were unchanged. In contrast, hyperinsulinaemia
       alone decreased plasma leucine concentrations (-35%; P<0.001)
       and leucine inflow (-20%; P<0.05) and outflow (-30%; P<0.01)
       into and out of forearm cell(s), it increased net intracellular
       leucine retention (P<0.03), and it did not change leucine
       release from forearm proteolysis (-20%; P=0.138), net leucine
       deamination to alpha-ketoisocaproate, leucine disposal into
       protein synthesis or net forearm protein balance. By considering
       all data together, leucine disposal into protein synthesis was
       directly correlated with leucine inflow into the cell (r=0.71;
       P<0.0001). These data indicate that the infusion of
       BCAA-enriched, AAA-deficient amino acids along with insulin is
       capable of stimulating forearm (i.e. muscle) protein anabolism
       in normal volunteers by enhancing intracellular leucine
       transport and protein synthesis. These effects are probably due
       to hyperaminoacidaemia and/or its interaction with
       hyperinsulinaemia, since they were not observed under conditions
       of hyperinsulinaemia alone.
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