Chorioretinal Vascular Oxygen Tension in Spontaneously Breathing Anesthetized Rats

• Published in: Ophthalmic research Vol. 39; no. 2; pp. 103 - 107
• Main Authors: Shakoor, A., Gupta, M., Blair, N.P., Shahidi, M.
• Format: Journal Article
• Language: English
• Published: Basel, Switzerland S. Karger AG 01.01.2007
• Subjects: Anesthetics, Combined; Animals; Catheters, Indwelling; Choroid - blood supply; Male; Original Paper; Oxygen - blood; Oxygen Consumption - physiology; Partial Pressure; Rats; Rats, Long-Evans; Respiration; Retinal Artery - physiology; Retinal Vein - physiology; Choroid; Retina; Oxygen
• ISSN: 0030-3747; 1423-0259
• DOI: 10.1159/000099246

Purpose: 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.