title: Contribution of amino acids and insulin to protein anabolism during meal absorption.
abstract: The contribution of dietary amino acids and endogenous hyperinsulinemia to prandial protein anabolism still has not been established. To this end, leucine estimates ([1-14C]leucine infusion, plasma alpha-ketoisocaproic acid [KIC] specific activity [SA] as precursor pool SA) of whole-body protein kinetics and fractional secretory rates (FSRs) of albumin, fibrinogen, antithrombin III, and immunoglobulin G (IgG) were measured in three groups of healthy volunteers during intragastric infusion of water (controls, n = 5), liquid glucose-lipid-amino acid (AA) meal (meal+AA, n = 7), or isocaloric glucose-lipid meal (meal-AA, n = 7) that induced the same insulin response as the meal+AA. The results of this study demonstrate that 1) by increasing (P < 0.01) whole-body protein synthesis and decreasing (P < 0.01) proteolysis, dietary amino acids account for the largest part (approximately 90%) of postprandial protein anabolism; 2) the ingestion of an isocaloric meal deprived of amino acids exerts a modest protein anabolic effect (10% of postprandial protein anabolism) by decreasing amino acid oxidation and increasing (P < 0.01) albumin synthesis; 3) albumin FSR is increased (approximately 20%) by postprandial hyperinsulinemia (meal-AA) and additionally increased (approximately 50%) by amino acid intake (meal+AA); 4) IgG FSR is stimulated (approximately 40%) by amino acids, not by insulin; and 5) fibrinogen and antithrombin III FSR are not regulated by amino acids or insulin.
authors.affiliation: Department of Internal Medicine, Endocrine and Metabolic Sciences, University of Perugia, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Volpi
authors.forename: P
authors.initials: P
authors.lastname: Lucidi
authors.forename: G
authors.initials: G
authors.lastname: Cruciani
authors.forename: F
authors.initials: F
authors.lastname: Monacchia
authors.forename: G
authors.initials: G
authors.lastname: Reboldi
authors.forename: P
authors.initials: P
authors.lastname: Brunetti
authors.forename: G B
authors.initials: GB
authors.lastname: Bolli
authors.forename: P
authors.initials: P
authors.lastname: De Feo
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000596:Amino Acids / Q000008:administration & dosage / Q000378:metabolism*; D000990:Antithrombin III / Q000032:analysis; D001786:Blood Glucose / Q000378:metabolism; D002096:C-Peptide / Q000097:blood; D002250:Carbon Radioisotopes; D004435:Eating; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005340:Fibrinogen / Q000032:analysis; D005934:Glucagon / Q000097:blood; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism*; D006801:Humans; D006946:Hyperinsulinism; D007074:Immunoglobulin G / Q000097:blood; D007328:Insulin / Q000097:blood*; D007408:Intestinal Absorption; D007651:Keto Acids / Q000097:blood; D007700:Kinetics; D007930:Leucine / Q000378:metabolism*; D050356:Lipid Metabolism; D008055:Lipids / Q000008:administration & dosage; D008297:Male; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism*; D011865:Radioisotope Dilution Technique; D012709:Serum Albumin / Q000032:analysis
chemical_list: D000596:Amino Acids; D001786:Blood Glucose; D002096:C-Peptide; D002250:Carbon Radioisotopes; D005230:Fatty Acids, Nonesterified; D007074:Immunoglobulin G; D007328:Insulin; D007651:Keto Acids; D008055:Lipids; D011506:Proteins; D012709:Serum Albumin; C013082:alpha-ketoisocaproic acid; D000990:Antithrombin III; D005340:Fibrinogen; D005934:Glucagon; D007930:Leucine; D005947:Glucose