title: Nitric oxide in acute brain injury: a pilot study of NO(x) concentrations in human brain microdialysates and their relationship with energy metabolism.
abstract: BACKGROUND
  This pilot microdialysis study in acute brain injury patients assessed the relationship between nitric oxide products (total nitrite plus nitrate, termed NO(x)) and energy-related molecules: glucose, lactate, pyruvate, glutamate and glycerol.
  
  
  METHODS
  Twelve patients (11 major head-injury and one subarachnoid haemorrhage) were studied, 11 of which had single catheters and one had two catheters, in the cerebral cortex. Catheters were perfused at 0.3 microL/min with CNS perfusion fluid. Collection vials were changed hourly. Microdialysates were analysed for energy-related molecules on a CMA600 or ISCUS analyser, and for NO(x) using a purge vessel (VCl3 plus HCl at 95 degrees C, purged with nitrogen) connected to a Sievers NOA 280i analyser.
  
  
  RESULTS
  The mean of mean NO(x) concentration (+/- SD) for the 13 catheters was 32.7 +/- 16.8 micromol/L, and the lactate/ pyruvate ratio was 38.6 +/- 20.1. Increasing NO(x) concentrations correlated significantly with decreasing lactate/ pyruvate ratio (Spearman r = -0.79, p = 0.0065), with decreasing lactate concentration (r = -0.59, p = 0.042), and with increasing glucose concentration (r = 0.71, p = 0.018).
  
  
  CONCLUSIONS
  These pilot data suggest that in injured brains, higher concentrations of nitric oxide are associated with more favourable metabolism. Nitric oxide may act beneficially by increasing blood flow and delivery of oxygen and glucose. Further patients are being recruited.
authors.affiliation: Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Box 167, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK. klc1000@wbic.cam.ac.uk
authors.forename: Keri L H
authors.initials: KL
authors.lastname: Carpenter
authors.forename: Ivan
authors.initials: I
authors.lastname: Timofeev
authors.forename: Pippa G
authors.initials: PG
authors.lastname: Al-Rawi
authors.forename: David K
authors.initials: DK
authors.lastname: Menon
authors.forename: John D
authors.initials: JD
authors.lastname: Pickard
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hutchinson
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry / Q000502:physiology; D001930:Brain Injuries / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D017551:Microdialysis / Q000379:methods; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D010865:Pilot Projects; D018709:Statistics, Nonparametric; D055815:Young Adult
chemical_list: D009569:Nitric Oxide