July 2019
Volume 60, Issue 9
Free
ARVO Annual Meeting Abstract  |   July 2019
Retinal Oxygen Delivery, Metabolism, and Extraction Fraction During Long-term Bilateral Common Carotid Artery Occlusion in Rats
Author Affiliations & Notes
  • Sophie Leahy
    Department of Ophthalmology, University of Southern California, Los Angeles, California, United States
  • James Burford
    Department of Ophthalmology, University of Southern California, Los Angeles, California, United States
  • Shayan Farzad
    Department of Ophthalmology, University of Southern California, Los Angeles, California, United States
  • Norman P Blair
    Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, United States
  • Mahnaz Shahidi
    Department of Ophthalmology, University of Southern California, Los Angeles, California, United States
  • Footnotes
    Commercial Relationships   Sophie Leahy, None; James Burford, None; Shayan Farzad, None; Norman Blair, None; Mahnaz Shahidi, University of Illinois at Chicago (P)
  • Footnotes
    Support  NIH research grant EY017918 and EY029220 and Research to Prevent Blindness
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 191. doi:
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      Sophie Leahy, James Burford, Shayan Farzad, Norman P Blair, Mahnaz Shahidi; Retinal Oxygen Delivery, Metabolism, and Extraction Fraction During Long-term Bilateral Common Carotid Artery Occlusion in Rats. Invest. Ophthalmol. Vis. Sci. 2019;60(9):191.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Although functional, biochemical, and anatomical changes have been reported in long-term ischemia rodent models, research regarding changes in oxygen metabolism is limited. The purpose of this study was to test the hypothesis that impairments of retinal oxygen delivery (DO2), metabolism (MO2) and extraction fraction (OEF) occur and are sustained with prolonged ischemia.

Methods : Retinal ischemia was induced in 24 rats by permanent bilateral ligation of common carotid arteries and 8 rats underwent sham procedures. Phosphorescence lifetime, microsphere fluorescence, and reflectance images were acquired in both eyes to measure retinal vascular oxygen tension, venous blood velocity and vessel diameter, respectively. Retinal arterial and venous oxygen contents (O2A, O2V), arteriovenous oxygen content difference (O2AV), and total retinal blood flow (TRBF) were determined. We calculated: DO2 = TRBF x O2A, MO2 = TRBF x O2AV, and OEF = MO2/DO2. Data from individual eyes were available in 4 study groups according to duration of ischemia: 3 hours (3H; N=10), 3 days (3D; N=10), 7 days (7D; N=14), and 14 days (14D; N=10) and one sham group (N=14; combined 3 days, 7 days, 14 days sham groups). DO2, MO2, and OEF were compared by linear mixed models accounting for data obtained in fellow eyes.

Results : In the sham group, DO2, MO2, and OEF were 814±172 nLO2/min, 403±121 nLO2/min, and 0.50±0.12 respectively. DO2 was lower in 3H (β = -711 nLO2/min), 3D (β = -575 nLO2/min), and 7D (β = -294 nLO2/min) groups compared to the sham group (P<0.003). MO2 was lower in 3H (β = -294 nLO2/min), 3D (β = -179 nLO2/min), and 7D (β = -136 nLO2/min) groups compared to the sham group (P<0.01). In the 14D group, DO2 (β = -184 nLO2/min) and MO2 (β = -46 nLO2/min) were not significantly different from the sham group (P>0.09). OEF was higher in 3H (β = 0.49) and 3D (β = 0.44) groups compared to the sham group (P<0.001). OEF was not significantly different in 7D (β = 0.09) and 14D (β = 0.13) groups compared to the sham group (P>0.11).

Conclusions : Permanent bilateral common carotid occlusion significantly, but not totally, impairs DO2, MO2 and OEF, but these recover within 14 days. This model may be useful to identify the characteristics of recoverable tissue with ischemia.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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