Influence of amino acid administration on whole-body leucine kinetics and resting metabolic rate in postabsorptive normal subjects.
1. We have investigated the effect of an amino acid mixture (Vamin 14; 57.4 +/- 10.2 mumol h-1 kg-1) on whole-body leucine kinetics, calculated by a steady-state reciprocal pool model, and resting metabolic rate in eight postabsorptive normal subjects. 2. Vamin 14 infusion increased whole-body leucine flux (P less than 0.001), leucine employed for protein synthesis (P less than 0.001), leucine oxidation (P less than 0.001), metabolic clearance rate of alpha-ketoisocaproic acid (P less than 0.05) and levels of all three branched-chain amino acids (P less than 0.001) compared with the basal situation. In contrast, whole-body proteolysis was reduced (P less than 0.05). 3. Resting metabolic rate was increased during Vamin 14 infusion (P less than 0.05) and was positively correlated with whole-body protein synthesis (n = 16, r = 0.6342, P less than 0.01; y = 0.605x + 173.7), as was the change in metabolic rate with the change in protein synthesis (n = 8, r = 0.772, P less than 0.05; y = 0.493x - 10.85). 4. Overall, Vamin 14 infusion was associated with increased blood glucose (P less than 0.001), although the observed increase in plasma glucagon (t = 2.012) and plasma insulin (t = 1.683) failed to reach statistical significance. 5. These data lend a measure of support to the hypothesis that the apparent increase in whole-body protein synthesis in insulin-dependent diabetic (type I) subjects during insulin withdrawal may be substrate related.
D000328:Adult; D000596:Amino Acids / Q000008:administration & dosage*; D001481:Basal Metabolism; D004573:Electrolytes; D005260:Female; D005947:Glucose; D006801:Humans; D007651:Keto Acids / Q000378:metabolism; D007700:Kinetics; D007930:Leucine / Q000378:metabolism*; D008297:Male; D010288:Parenteral Nutrition; D057947:Parenteral Nutrition Solutions; D012996:Solutions
D000596:Amino Acids; D004573:Electrolytes; D007651:Keto Acids; D057947:Parenteral Nutrition Solutions; D012996:Solutions; C545824:amino-acid, glucose, and electrolyte solution; C013082:alpha-ketoisocaproic acid; D007930:Leucine; D005947:Glucose