title: Effects of dexmedetomidine on microregional O2 balance during reperfusion after focal cerebral ischemia.
abstract: BACKGROUND
  This study was performed to determine whether there is an association between microregional O2 balance and neuronal survival in cerebral ischemia-reperfusion using dexmedetomidine, an α2-adrenoreceptor agonist and a sedative.
  
  
  METHODS
  Rats were subjected to 1 hour middle cerebral artery occlusion and a 2-hour reperfusion. During reperfusion, normal saline (n = 14) or dexmedetomidine 1 μg/kg/minute (n = 14) was infused intravenously. At 2 hours of reperfusion, regional cerebral blood flow using (14)C-iodoantipyrine autoradiography, microregional arterial and venous (20-60 μm in diameter) O2 saturation (SvO2) using cryomicrospectrophotometry, and the size of cortical infarction were determined.
  
  
  RESULTS
  Ischemia-reperfusion decreased microregional SvO2 (52.9 ± 3.7% vs. 61.1 ± .6%, P < .005) with increased variation or heterogeneity (P < .0001) with similar regional cerebral blood flow and O2 consumption. Dexmedetomidine during reperfusion decreased the heterogeneity of SvO2 that was analyzed with an analysis of variance (P < .01) and reported as coefficient of variation (100 × standard deviation/Mean) (11.8 vs. 16.4). The number of veins with O2 saturation less than 50% decreased with dexmedetomidine (13/80 vs. 27/81, P < .01). The percentage of cortical infarct in total cortex was smaller with dexmedetomidine (8.3 ± 2.2% vs. 12.6 ± 1.5%, P < .005).
  
  
  CONCLUSIONS
  In the cerebral ischemic reperfused cortex, dexmedetomidine decreased the heterogeneity of SvO2 and the number of small veins with low O2 saturation suggesting improved microregional O2 supply/consumption balance. The improvement was accompanied by the reduced size of cortical infarction.
authors.affiliation: Department of Anesthesiology, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey. Electronic address: chi@rwjms.rutgers.edu.
authors.forename: Oak Z
authors.initials: OZ
authors.lastname: Chi
authors.affiliation: Department of Anesthesiology, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey.
authors.forename: Jeremy
authors.initials: J
authors.lastname: Grayson
authors.affiliation: Department of Anesthesiology, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey.
authors.forename: Sylviana
authors.initials: S
authors.lastname: Barsoum
authors.affiliation: Department of Anesthesiology, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey.
authors.forename: Xia
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Anesthesiology, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey.
authors.forename: Aliraza
authors.initials: A
authors.lastname: Dinani
authors.affiliation: Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey.
authors.forename: Harvey R
authors.initials: HR
authors.lastname: Weiss
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000627:therapeutic use*; D000818:Animals; D001784:Blood Gas Analysis; D002545:Brain Ischemia / Q000188:drug therapy* / Q000378:metabolism* / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology; D020927:Dexmedetomidine / Q000627:therapeutic use*; D006439:Hemodynamics; D020244:Infarction, Middle Cerebral Artery / Q000188:drug therapy / Q000473:pathology; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects*; D011149:Pons / Q000473:pathology; D051381:Rats; D011916:Rats, Inbred F344; D015427:Reperfusion Injury / Q000188:drug therapy* / Q000378:metabolism* / Q000503:physiopathology
chemical_list: D000316:Adrenergic alpha-Agonists; D020927:Dexmedetomidine
keywords: Cerebral ischemia reperfusion; cerebral O(2) supply and consumption balance; cerebral venous O(2) saturation; α(2) agonist