title: Radial oxygen gradients over rat cortex arterioles.
abstract: OBJECTIVE
  We present the results of the visualisation of radial oxygen gradients in rats' cortices and their potential use in neurocritical management.
  
  
  METHODS
  PO₂ maps of the cortex of ten sedated, intubated and controlled ventilated Wistar rats were obtained with a camera (SensiMOD, PCO, Kelheim, Germany). Those pictures were analysed and edited by a custom-made software. A virtual matrix, designed to evaluate the cortical O₂ partial pressure, was placed vertically to the artery under investigation, and afterwards multiple regions of interest were measured (width 10 pixels, length 15-50 pixels). The results showed a map of the cerebral oxygenation, which allowed us to calculate radial oxygen gradients over arterioles. Three groups were defined according to the level of the arterial pO₂: PaO₂ < 80, PaO₂ 80-120 and PaO₂ > 120. Gradients were analysed from the middle of the vessel to its border (1), from the border into the parenchyma next to the vessel (2) and a combination of both (3).
  
  
  RESULTS
  Gradient 1 showed significantly different cortical pO₂ values between the three different groups. The mean pO₂ values were 2.62, 5.29 and 5.82 mmHg/mm. Gradient 2 measured 0.56, 0.90 and 1.02 mmHg/mm respectively. Gradient 3 showed significant results between the groups with values of 3.18, 6.19 and 6.84 mmHg/mm.
  
  
  CONCLUSIONS
  Using these gradients, it is possible to describe and compare the distribution of oxygen to the brain parenchyma. With the presented technique, it is possible to detect pO₂ changes in the oxygen supply of the brain cortex.
authors.affiliation: Klinik und Poliklinik für Neurochirurgie, Universität Regensburg, Germany. Michael-Galler@t-online.de
authors.forename: Michael
authors.initials: M
authors.lastname: Galler
authors.forename: Stefan
authors.initials: S
authors.lastname: Moritz
authors.forename: Gregor
authors.initials: G
authors.lastname: Liebsch
authors.forename: Chris
authors.initials: C
authors.lastname: Woertgen
authors.forename: Alexander
authors.initials: A
authors.lastname: Brawanski
authors.forename: Jan
authors.initials: J
authors.lastname: Warnat
mesh_terms: D000818:Animals; D001160:Arterioles / Q000378:metabolism*; D001931:Brain Mapping / Q000379:methods; D002536:Cerebral Arteries / Q000378:metabolism*; D002540:Cerebral Cortex / Q000098:blood supply* / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008163:Luminescent Measurements / Q000379:methods; D008833:Microcirculation / Q000502:physiology; D055096:Optical Devices / Q000592:standards; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology*; D010313:Partial Pressure; D051381:Rats; D017208:Rats, Wistar
chemical_list: D010100:Oxygen