Amino acid infusion increases the sensitivity of muscle protein synthesis in vivo to insulin. Effect of branched-chain amino acids.
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.
D000596:Amino Acids / Q000097:blood / Q000494:pharmacology*; D000818:Animals; D005947:Glucose / Q000494:pharmacology; D007262:Infusions, Intravenous; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains
D000596:Amino Acids; D007328:Insulin; D009124:Muscle Proteins; D005947:Glucose