Purpose: To establish baseline and variability of oxygen tension (PO2) 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 PO2. Methods: Our previously established optical section phosphorescence imaging technique was utilized to measure PO2 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 PO2. The PO2 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 PO2 was 52 ± 7 mm Hg (mean ± SD) in group 2. In group 1, the average PO2 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 PO2 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 PO2 measurements in spontaneously breathing anesthetized rats have a relatively low variability, indicating that PO2 changes due to various physiological alterations can be reliably assessed.

Keywords:
Choroid, Oxygen, Retina
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© 2007 S. Karger AG, Basel
2007
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