title: Chorioretinal vascular oxygen tension in spontaneously breathing anesthetized rats.
abstract: OBJECTIVE
  To establish baseline and variability of oxygen tension (PO(2)) measurements in the choroid, retinal arteries, capillaries, and veins of spontaneously breathing anesthetized rats and determine the effect of a moderate surgical procedure on the chorioretinal PO(2).
  
  
  METHODS
  Our previously established optical section phosphorescence imaging technique was utilized to measure PO(2) in the chorioretinal vasculatures. Imaging was performed in 29 spontaneously breathing rats under ketamine/xylazine anesthesia. In 7 rats, blood was drawn using a surgically implanted femoral arterial catheter and analyzed to determine the systemic arterial PO(2). The PO(2) measurements in 22 rats without surgery (group 1) and 7 surgically instrumented rats (group 2) were statistically compared. The intrasubject variability was calculated by the average standard deviation (SD) of repeated measurements.
  
  
  RESULTS
  The average systemic arterial PO(2) was 52 +/- 7 mm Hg (mean +/- SD) in group 2. In group 1, the average PO(2) measurements in the choroid, retinal arteries, capillaries, and veins were 50 +/- 11, 40 +/- 5, 39 +/- 6, and 30 +/- 5 mm Hg, respectively. No statistically significant PO(2) differences in any of the chorioretinal vasculatures were found between the two groups (p > 0.4). The intrasubject variability was 3 mm Hg in the choroid, retinal arteries, capillaries, and veins.
  
  
  CONCLUSIONS
  Chorioretinal PO(2) measurements in spontaneously breathing anesthetized rats have a relatively low variability, indicating that PO(2) changes due to various physiological alterations can be reliably assessed.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL 60612, USA.
authors.forename: A
authors.initials: A
authors.lastname: Shakoor
authors.forename: M
authors.initials: M
authors.lastname: Gupta
authors.forename: N P
authors.initials: NP
authors.lastname: Blair
authors.forename: M
authors.initials: M
authors.lastname: Shahidi
mesh_terms: D019162:Anesthetics, Combined; D000818:Animals; D002408:Catheters, Indwelling; D002829:Choroid / Q000098:blood supply*; D008297:Male; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology; D010313:Partial Pressure; D051381:Rats; D020318:Rats, Long-Evans; D012119:Respiration; D012161:Retinal Artery / Q000502:physiology*; D012169:Retinal Vein / Q000502:physiology*
chemical_list: D019162:Anesthetics, Combined; D010100:Oxygen