title: Glucose and insulin administration while maintaining normoglycemia inhibits whole body protein breakdown and synthesis after cardiac surgery.
abstract: We investigated the effect of insulin administered as part of a hyperinsulinemic-normoglycemic clamp on protein metabolism after coronary artery bypass grafting (CABG) surgery. Eighteen patients were studied, with nine patients in the control group receiving standard metabolic care and nine patients receiving insulin (5 mU·kg(-1)·min(-1)). Whole body glucose production, protein breakdown, synthesis, and oxidation were determined using stable isotope tracer kinetics (l-[1-(13)C]leucine, [6,6-(2)H2]glucose) before and 6 h after the procedure. Plasma amino acids, cortisol, and lactate were also measured. Endogenous glucose production (preoperatively 10.0 ± 1.6, postoperatively 3.7 ± 2.5 μmol·kg(-1)·min(-1); P = 0.0001), protein breakdown (preoperatively 105.3 ± 9.8, postoperatively 85.2 ± 9.2 mmol·kg(-1)·h(-1); P = 0.0005) and synthesis (preoperatively 88.7 ± 8.7, postoperatively 72.4 ± 8.4 mmol·kg(-1)·h(-1); P = 0.0005) decreased in the presence of hyperinsulinemia, whereas both parameters remained unchanged in the control group. A positive correlation between endogenous glucose production and protein breakdown was observed in the insulin group (r(2) = 0.385). Whole body protein oxidation and balance decreased after surgery in patients receiving insulin without reaching statistical significance. In the insulin group the plasma concentrations of 13 of 20 essential and nonessential amino acids decreased to a significantly greater extent than in the control group. In summary, supraphysiological hyperinsulinemia, while maintaining normoglycemia, decreased whole body protein breakdown and synthesis in patients undergoing CABG surgery. However, net protein balance remained negative.
authors.affiliation: Department of Anaesthesia, McGill University Health Center, Montreal, Canada; Department of Critical Care, McGill University Health Center, Montreal, Canada; roupen.hatzakorzian@muhc.mcgill.ca.
authors.forename: Roupen
authors.initials: R
authors.lastname: Hatzakorzian
authors.affiliation: Department of Cardiovascular Surgery, McGill University Health Center, Montreal, Canada;
authors.forename: Dominique
authors.initials: D
authors.lastname: Shum-Tim
authors.affiliation: School of Dietetics and Human Nutrition, McGill University, Montreal, Canada; and.
authors.forename: Linda
authors.initials: L
authors.lastname: Wykes
authors.affiliation: Department of Anaesthesia, McGill University Health Center, Montreal, Canada;
authors.forename: Ansgar
authors.initials: A
authors.lastname: Hülshoff
authors.affiliation: Department of Endocrinology and Metabolism, McGill University Health Center, Montreal, Canada.
authors.forename: Helen
authors.initials: H
authors.lastname: Bui
authors.affiliation: School of Dietetics and Human Nutrition, McGill University, Montreal, Canada; and.
authors.forename: Evan
authors.initials: E
authors.lastname: Nitschmann
authors.affiliation: Department of Anaesthesia, McGill University Health Center, Montreal, Canada;
authors.forename: Ralph
authors.initials: R
authors.lastname: Lattermann
authors.affiliation: Department of Anaesthesia, McGill University Health Center, Montreal, Canada;
authors.forename: Thomas
authors.initials: T
authors.lastname: Schricker
mesh_terms: D000368:Aged; D000596:Amino Acids / Q000097:blood; D001026:Coronary Artery Bypass; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage*; D007328:Insulin / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D011182:Postoperative Care / Q000379:methods*; D011184:Postoperative Period; D014176:Protein Biosynthesis / Q000187:drug effects*; D011506:Proteins / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D007004:Hypoglycemic Agents; D007328:Insulin; D011506:Proteins
keywords: amino acids; cardiac surgery; insulin; protein breakdown; protein synthesis