title: Perioperative perturbations in carnitine metabolism are attenuated by preoperative carbohydrate treatment: Another mechanism by which preoperative feeding may attenuate development of postoperative insulin resistance.
abstract: OBJECTIVE
  Fasting increases lipid flux into mitochondria causing excessive β-oxidation, carnitine acylation and impaired cellular glucose uptake. Preoperative carbohydrate treatment (PCT) attenuates postoperative insulin resistance, but mechanisms underlying this and the effects on carnitine metabolism remain largely unknown.
  
  
  METHODS
  Pre-, intra- and-postoperative (day 1) plasma, and intraoperative rectus muscle mitochondrial free (FC), acyl (AC) and total (TC) carnitine concentrations were determined radioenzymatically in non-diabetic patients undergoing laparoscopic cholecystectomy in a post hoc analysis of a randomised double-blind study (NCT00662376). Patients received 600 ml of a carbohydrate-based drink (ONS, Fresenuis Kabi, N = 15, 50 g carbohydrate, 15 g glutamine and antioxidants/300 ml) or placebo (N = 15, 0 g carbohydrate) the evening before surgery, and 300 ml 3-4 h pre-anaesthesia.
  
  
  RESULTS
  No intra- or intergroup differences occurred in pre- or intraoperative plasma FC, TC or AC concentrations. Postoperatively, plasma TC and FC concentrations increased in the placebo group (p = 0.005 and p = 0.013). In the ONS group, postoperative increases occurred in plasma TC (p = 0.048). Increases in postoperative plasma TC and FC concentrations were attenuated in the ONS group (p = 0.013 and p = 0.044, respectively). No intergroup differences occurred in intraoperative mitochondrial carnitine concentrations.
  
  
  CONCLUSIONS
  Preventing excessive/incomplete mitochondrial β-oxidation, characterised by perturbed carnitine metabolism, may be a mechanism by which PCT attenuates the reduction in postoperative insulin sensitivity.
authors.affiliation: Division of Gastrointestinal Surgery, Nottingham Digestive Diseases Centre NIHR Biomedical Research Unit, Nottingham University Hospitals, Queen's Medical Centre, Nottingham NG7 2UH, UK.
authors.forename: Sherif
authors.initials: S
authors.lastname: Awad
authors.forename: Francis
authors.initials: F
authors.lastname: Stephens
authors.forename: Chris
authors.initials: C
authors.lastname: Shannon
authors.forename: Dileep N
authors.initials: DN
authors.lastname: Lobo
mesh_terms: D000215:Acylation; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000975:Antioxidants / Q000008:administration & dosage; D015992:Body Mass Index; D002331:Carnitine / Q000097:blood / Q000378:metabolism*; D017081:Cholecystectomy, Laparoscopic; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004311:Double-Blind Method; D005215:Fasting; D005947:Glucose / Q000493:pharmacokinetics; D005973:Glutamine / Q000008:administration & dosage; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D008055:Lipids / Q000097:blood; D008875:Middle Aged; D008928:Mitochondria / Q000378:metabolism; D011184:Postoperative Period; D011300:Preoperative Care / Q000379:methods*; D055815:Young Adult
chemical_list: D000975:Antioxidants; D004040:Dietary Carbohydrates; D007328:Insulin; D008055:Lipids; D005973:Glutamine; D005947:Glucose; D002331:Carnitine