title: Cerebral ischemia and reperfusion increases the heterogeneity of local oxygen supply/consumption balance.
abstract: OBJECTIVE
  After cerebral vessel blockage, local blood flow and O2 consumption becomes lower and oxygen extraction increases. With reperfusion, blood flow is partially restored. We examined the effects of ischemia-reperfusion on the heterogeneity of local venous oxygen saturation in rats in order to determine the pattern of microregional O2 supply/consumption balance in reperfusion.
  
  
  METHODS
  The middle cerebral artery was blocked for 1 hour using the internal carotid approach in 1 group (n=9) and was then reperfused for 2 hours in another group (n=9) of isoflurane-anesthetized rats. Regional cerebral blood flow was determined using a C(14)-iodoantipyrine autoradiographic technique. Regional small vessel arterial and venous oxygen saturations were determined microspectrophotometrically.
  
  
  RESULTS
  After 1 hour of ischemia, local cerebral blood flow (92±10 versus 50±10 mL/min per 100 g) and O2 consumption (4.5±0.6 versus 2.7±0.5 mL O2/min per 100 g) decreased compared with the contralateral cortex. Oxygen extraction increased (4.7±0.2 versus 5.4±0.3 mL O2/100 mL) and the variation in small vein (20-60 μm) O2 saturation as determined by its coefficient of variation (=100×SD/mean) increased (5.5 versus 10.5). With 2 hours of reperfusion, the blood flow decrement was reduced and O2 consumption returned to the value in the contralateral cortex. Oxygen extraction remained elevated in the ischemic-reperfused area and the coefficient of variation of small vein O2 saturation increased further (17.3).
  
  
  CONCLUSIONS
  These data indicated continued reduction of O2 supply/consumption balance with reperfusion. They also demonstrated many small regions of low oxygenation within the reperfused cortical region.
authors.affiliation: Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, USA. hweiss@rwjms.rutgers.edu
authors.forename: Harvey R
authors.initials: HR
authors.lastname: Weiss
authors.forename: Jeremy
authors.initials: J
authors.lastname: Grayson
authors.forename: Xia
authors.initials: X
authors.lastname: Liu
authors.forename: Sylviana
authors.initials: S
authors.lastname: Barsoum
authors.forename: Harsh
authors.initials: H
authors.lastname: Shah
authors.forename: Oak Z
authors.initials: OZ
authors.lastname: Chi
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000097:blood / Q000000981:diagnostic imaging / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004195:Disease Models, Animal; D008297:Male; D015591:Microspectrophotometry; D020768:Middle Cerebral Artery / Q000293:injuries / Q000502:physiology / Q000503:physiopathology; D010100:Oxygen / Q000097:blood / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D011859:Radiography; D051381:Rats; D011916:Rats, Inbred F344; D015427:Reperfusion Injury / Q000097:blood / Q000378:metabolism* / Q000503:physiopathology*
chemical_list: D010100:Oxygen
keywords: cerebral O2 consumption; cerebral O2 supply/consumption balance; cerebral blood flow; ischemia-reperfusion