title: Increasing Insulin Availability Does Not Augment Postprandial Muscle Protein Synthesis Rates in Healthy Young and Older Men.
abstract: BACKGROUND
  Skeletal muscle protein synthesis is highly responsive to food intake. It has been suggested that the postprandial increase in circulating insulin modulates the muscle protein synthetic response to feeding.
  
  
  OBJECTIVE
  The objective of the study was to investigate whether a greater postprandial rise in circulating insulin level increases amino acid uptake in muscle and augments postprandial muscle protein synthesis rates.
  
  
  METHODS
  Forty-eight healthy young (age 22 ± 1 y; body mass index 22.0 ± 0.3 kg/m2) and older males (age 68 ± 1 y; body mass index 26.3 ± 0.4 kg/m2) ingested 20 g intrinsically L-[1-13C]-leucine- and L-[1-13C]-phenylalanine-labeled casein protein with or without local insulin infusion. Primed continuous infusions of L-[1-13C]-leucine and L-[ring-2H5]-phenylalanine were applied, with arterial and venous blood samples and muscle biopsies being collected during a 5-hour postprandial period.
  
  
  RESULTS
  Insulin administration did not increase overall leg blood flow (P = .509) but increased amino acid uptake over the leg in both young and older subjects (P = .003). The greater amino acid uptake over the leg did not further increase postprandial muscle protein synthesis rates (0.050% ± 0.006% and 0.037% ± 0.004% per hour vs 0.044% ± 0.004% and 0.037% ± 0.002% per hour in the insulin-stimulated vs control condition in the young and older groups, respectively; P = .804) and did not affect postprandial deposition of dietary protein-derived amino acids in de novo muscle protein (P = .872).
  
  
  CONCLUSIONS
  Greater postprandial plasma insulin availability stimulates amino acid uptake over the leg but does not further augment postprandial muscle protein synthesis rates or stimulate the postprandial deposition of protein derived amino acids into de novo muscle protein in healthy young and older men.
authors.affiliation: Top Institute Food and Nutrition (B.B.L.G., A.M.H.H., H.M.H., J.v.K., L.J.C.v.L.), 6709 PG Wageningen, The Netherlands; Departments of Human Biology and Movement Sciences (B.B.L.G., A.M.H.H., H.M.H., L.J.C.v.L.), Radiology (M.d.H.), Clinical Genetics, and Surgery (M.P.), Laboratory Biochemical Genetics (J.B.), and Central Diagnostic Laboratory (W.K.W.H.W.), Maastricht University Medical Centre, 6200 MD Maastricht, The Netherlands; and Department of Nutrition and Metabolism (B.B.R.), University of Texas Medical Branch, Galveston, Texas 77550.
authors.forename: Bart B L
authors.initials: BB
authors.lastname: Groen
authors.affiliation: Top Institute Food and Nutrition (B.B.L.G., A.M.H.H., H.M.H., J.v.K., L.J.C.v.L.), 6709 PG Wageningen, The Netherlands; Departments of Human Biology and Movement Sciences (B.B.L.G., A.M.H.H., H.M.H., L.J.C.v.L.), Radiology (M.d.H.), Clinical Genetics, and Surgery (M.P.), Laboratory Biochemical Genetics (J.B.), and Central Diagnostic Laboratory (W.K.W.H.W.), Maastricht University Medical Centre, 6200 MD Maastricht, The Netherlands; and Department of Nutrition and Metabolism (B.B.R.), University of Texas Medical Branch, Galveston, Texas 77550.
authors.forename: Astrid M H
authors.initials: AM
authors.lastname: Horstman
authors.affiliation: Top Institute Food and Nutrition (B.B.L.G., A.M.H.H., H.M.H., J.v.K., L.J.C.v.L.), 6709 PG Wageningen, The Netherlands; Departments of Human Biology and Movement Sciences (B.B.L.G., A.M.H.H., H.M.H., L.J.C.v.L.), Radiology (M.d.H.), Clinical Genetics, and Surgery (M.P.), Laboratory Biochemical Genetics (J.B.), and Central Diagnostic Laboratory (W.K.W.H.W.), Maastricht University Medical Centre, 6200 MD Maastricht, The Netherlands; and Department of Nutrition and Metabolism (B.B.R.), University of Texas Medical Branch, Galveston, Texas 77550.
authors.forename: Henrike M
authors.initials: HM
authors.lastname: Hamer
authors.affiliation: Top Institute Food and Nutrition (B.B.L.G., A.M.H.H., H.M.H., J.v.K., L.J.C.v.L.), 6709 PG Wageningen, The Netherlands; Departments of Human Biology and Movement Sciences (B.B.L.G., A.M.H.H., H.M.H., L.J.C.v.L.), Radiology (M.d.H.), Clinical Genetics, and Surgery (M.P.), Laboratory Biochemical Genetics (J.B.), and Central Diagnostic Laboratory (W.K.W.H.W.), Maastricht University Medical Centre, 6200 MD Maastricht, The Netherlands; and Department of Nutrition and Metabolism (B.B.R.), University of Texas Medical Branch, Galveston, Texas 77550.
authors.forename: Michiel
authors.initials: M
authors.lastname: de Haan
authors.affiliation: Top Institute Food and Nutrition (B.B.L.G., A.M.H.H., H.M.H., J.v.K., L.J.C.v.L.), 6709 PG Wageningen, The Netherlands; Departments of Human Biology and Movement Sciences (B.B.L.G., A.M.H.H., H.M.H., L.J.C.v.L.), Radiology (M.d.H.), Clinical Genetics, and Surgery (M.P.), Laboratory Biochemical Genetics (J.B.), and Central Diagnostic Laboratory (W.K.W.H.W.), Maastricht University Medical Centre, 6200 MD Maastricht, The Netherlands; and Department of Nutrition and Metabolism (B.B.R.), University of Texas Medical Branch, Galveston, Texas 77550.
authors.forename: Janneau
authors.initials: J
authors.lastname: van Kranenburg
authors.affiliation: Top Institute Food and Nutrition (B.B.L.G., A.M.H.H., H.M.H., J.v.K., L.J.C.v.L.), 6709 PG Wageningen, The Netherlands; Departments of Human Biology and Movement Sciences (B.B.L.G., A.M.H.H., H.M.H., L.J.C.v.L.), Radiology (M.d.H.), Clinical Genetics, and Surgery (M.P.), Laboratory Biochemical Genetics (J.B.), and Central Diagnostic Laboratory (W.K.W.H.W.), Maastricht University Medical Centre, 6200 MD Maastricht, The Netherlands; and Department of Nutrition and Metabolism (B.B.R.), University of Texas Medical Branch, Galveston, Texas 77550.
authors.forename: Jörgen
authors.initials: J
authors.lastname: Bierau
authors.affiliation: Top Institute Food and Nutrition (B.B.L.G., A.M.H.H., H.M.H., J.v.K., L.J.C.v.L.), 6709 PG Wageningen, The Netherlands; Departments of Human Biology and Movement Sciences (B.B.L.G., A.M.H.H., H.M.H., L.J.C.v.L.), Radiology (M.d.H.), Clinical Genetics, and Surgery (M.P.), Laboratory Biochemical Genetics (J.B.), and Central Diagnostic Laboratory (W.K.W.H.W.), Maastricht University Medical Centre, 6200 MD Maastricht, The Netherlands; and Department of Nutrition and Metabolism (B.B.R.), University of Texas Medical Branch, Galveston, Texas 77550.
authors.forename: Martijn
authors.initials: M
authors.lastname: Poeze
authors.affiliation: Top Institute Food and Nutrition (B.B.L.G., A.M.H.H., H.M.H., J.v.K., L.J.C.v.L.), 6709 PG Wageningen, The Netherlands; Departments of Human Biology and Movement Sciences (B.B.L.G., A.M.H.H., H.M.H., L.J.C.v.L.), Radiology (M.d.H.), Clinical Genetics, and Surgery (M.P.), Laboratory Biochemical Genetics (J.B.), and Central Diagnostic Laboratory (W.K.W.H.W.), Maastricht University Medical Centre, 6200 MD Maastricht, The Netherlands; and Department of Nutrition and Metabolism (B.B.R.), University of Texas Medical Branch, Galveston, Texas 77550.
authors.forename: Will K W H
authors.initials: WK
authors.lastname: Wodzig
authors.affiliation: Top Institute Food and Nutrition (B.B.L.G., A.M.H.H., H.M.H., J.v.K., L.J.C.v.L.), 6709 PG Wageningen, The Netherlands; Departments of Human Biology and Movement Sciences (B.B.L.G., A.M.H.H., H.M.H., L.J.C.v.L.), Radiology (M.d.H.), Clinical Genetics, and Surgery (M.P.), Laboratory Biochemical Genetics (J.B.), and Central Diagnostic Laboratory (W.K.W.H.W.), Maastricht University Medical Centre, 6200 MD Maastricht, The Netherlands; and Department of Nutrition and Metabolism (B.B.R.), University of Texas Medical Branch, Galveston, Texas 77550.
authors.forename: Blake B
authors.initials: BB
authors.lastname: Rasmussen
authors.affiliation: Top Institute Food and Nutrition (B.B.L.G., A.M.H.H., H.M.H., J.v.K., L.J.C.v.L.), 6709 PG Wageningen, The Netherlands; Departments of Human Biology and Movement Sciences (B.B.L.G., A.M.H.H., H.M.H., L.J.C.v.L.), Radiology (M.d.H.), Clinical Genetics, and Surgery (M.P.), Laboratory Biochemical Genetics (J.B.), and Central Diagnostic Laboratory (W.K.W.H.W.), Maastricht University Medical Centre, 6200 MD Maastricht, The Netherlands; and Department of Nutrition and Metabolism (B.B.R.), University of Texas Medical Branch, Galveston, Texas 77550.
authors.forename: Luc J C
authors.initials: LJ
authors.lastname: van Loon
mesh_terms: D065567:Absorption, Physiological / Q000187:drug effects; D000328:Adult; D000368:Aged; D000375:Aging; D000596:Amino Acids / Q000097:blood / Q000378:metabolism*; D001706:Biopsy; D002247:Carbon Isotopes; D002364:Caseins / Q000378:metabolism; D005263:Femoral Artery; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism / Q000494:pharmacology; D007261:Infusions, Intra-Arterial; D007328:Insulin / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism*; D019518:Postprandial Period; D052097:Quadriceps Muscle; D012039:Regional Blood Flow / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects; D055815:Young Adult
chemical_list: D000596:Amino Acids; D002247:Carbon Isotopes; D002364:Caseins; D007004:Hypoglycemic Agents; D007328:Insulin; D009124:Muscle Proteins