title: The pattern of amino acid exchange across the brain is unaffected by intravenous glutamine supplementation in head trauma patients.
abstract: OBJECTIVE
  Exogenous intravenous glutamine supplementation to head trauma patients leaves intracerebral glutamate concentration unaffected. The effect of an exogenous supply upon glutamine and glutamate exchange across the brain has still not been characterised.
  
  
  METHODS
  A prospective randomised cross-over study, where i.v. glutamine dipeptide was compared with placebo. Arterio-venous concentration differences of free amino acids across the brain and amino acid flux across the leg were measured. In addition, the endogenous glutamine production was calculated. Fifteen mechanically ventilated head trauma patients with GCS < or =8 were included and studied during two consecutive 24-h periods on days 2-5 following head trauma.
  
  
  RESULTS
  Glutamine was continuously released from both the brain and the leg. The arterio-venous (a-v) concentration differences over the brain were calculated to be -49+/-26 and -27+/-14 micromol/L during the treatment and control periods respectively, showing a continuous release of glutamine (p<0.0001). On the other hand, the a-v difference of glutamate was not different from zero (p>0.2). The whole-body glutamine rate of appearance (R(a)) was calculated to be 218+/-75micromol/kg body weight/h.
  
  
  CONCLUSIONS
  Intravenous glutamine supplementation to head trauma patients was associated with an unaffected amino acid exchange pattern across head and leg, without any measurable uptake of glutamate across the brain. Endogenous glutamine production was in the normal range despite the low plasma glutamine concentration. This pilot study opens the possibility to perform prospective clinical trials in head trauma patients to evaluate the clinical efficacy of exogenous glutamine supplementation.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, K32, Karolinska University Hospital, Huddinge, SE 141-86 Stockholm, Sweden. agneta.berg@ki.se
authors.forename: Agneta
authors.initials: A
authors.lastname: Berg
authors.forename: Bo Michael
authors.initials: BM
authors.lastname: Bellander
authors.forename: Michael
authors.initials: M
authors.lastname: Wanecek
authors.forename: Ake
authors.initials: A
authors.lastname: Norberg
authors.forename: Urban
authors.initials: U
authors.lastname: Ungerstedt
authors.forename: Olav
authors.initials: O
authors.lastname: Rooyackers
authors.forename: Jan
authors.initials: J
authors.lastname: Wernerman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000378:metabolism*; D006259:Craniocerebral Trauma / Q000378:metabolism*; D003430:Cross-Sectional Studies; D004151:Dipeptides / Q000008:administration & dosage / Q000493:pharmacokinetics; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism*; D005973:Glutamine / Q000008:administration & dosage* / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010288:Parenteral Nutrition; D010865:Pilot Projects; D011446:Prospective Studies; D055815:Young Adult
chemical_list: D004151:Dipeptides; D005973:Glutamine; D018698:Glutamic Acid