Department of Ophthalmology, University of Southern California, Los Angeles, California, United States.
Department of Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, Illinois, United States.
Invest Ophthalmol Vis Sci. 2022 Jun 1;63(6):30. doi: 10.1167/iovs.63.6.30.
The purpose of the current study was to test the hypothesis that responses of total retinal blood flow (TRBF), inner retinal oxygen delivery (DO2), metabolism (MO2), and extraction fraction (OEF) to hyperoxia are higher after minutes of bilateral common carotid artery occlusion (BCCAO) as compared to days of BCCAO.
Twenty-eight rats were subjected to BCCAO for 30 minutes (n = 12), 1 day (n = 8), or 3 days (n = 8). Eight of the 12 rats were also evaluated at baseline, prior to BCCAO. During room air breathing (RA) and 100% O2 inspiration (hyperoxia), blood flow and phosphorescence lifetime imaging were performed to measure TRBF and vascular O2 contents, respectively. DO2, MO2, and OEF were calculated from these measurements.
After 30 minutes or 3 days of BCCAO, TRBF did not differ between RA and hyperoxia conditions (P ≥ 0.14) but decreased under hyperoxia after 1 day (P = 0.01). Compared to RA, DO2 and MO2 were increased under hyperoxia after 30 minutes of BCCAO (P ≤ 0.02). Additionally, MO2 was decreased under hyperoxia after 1 day of BCCAO (P = 0.04). OEF was decreased under hyperoxia compared to RA (P < 0.001). Under hyperoxia, TRBF and DO2 were reduced after all BCCAO durations compared to baseline (P ≤ 0.04), whereas MO2 did not differ from baseline after 30 minutes of BCCAO (P = 1.00).
The findings indicate that hyperoxia introduced minutes after ischemia can reduce DO2 impairments and potentially return MO2 to approximately normal values. This information contributes to the knowledge of the effect of supplemental oxygen intervention on TRBF, DO2, MO2, and OEF outcomes after variable durations of ischemia.
本研究旨在验证以下假设，即在双侧颈总动脉阻塞（BCCAO）后数分钟内，与数天相比，总视网膜血流（TRBF）、内视网膜氧输送（DO2）、代谢（MO2）和提取分数（OEF）对高氧的反应更高。
28 只大鼠接受 30 分钟（n = 12）、1 天（n = 8）或 3 天（n = 8）的 BCCAO。其中 12 只大鼠中的 8 只在 BCCAO 前进行了基线评估。在进行空气呼吸（RA）和 100%氧气吸入（高氧）时，进行血流和磷光寿命成像以分别测量 TRBF 和血管氧含量。从这些测量中计算 DO2、MO2 和 OEF。
在 30 分钟或 3 天的 BCCAO 后，RA 和高氧条件下的 TRBF 没有差异（P≥0.14），但 1 天后高氧下 TRBF 下降（P = 0.01）。与 RA 相比，30 分钟 BCCAO 后高氧下 DO2 和 MO2 增加（P≤0.02）。此外，1 天后高氧下 MO2 降低（P = 0.04）。与 RA 相比，高氧下 OEF 降低（P<0.001）。与基线相比，所有 BCCAO 持续时间下高氧下 TRBF 和 DO2 降低（P≤0.04），而 30 分钟 BCCAO 后 MO2 与基线无差异（P = 1.00）。
这些发现表明，在缺血后几分钟内引入的高氧可以减少 DO2 损伤，并可能使 MO2 恢复到接近正常水平。这些信息有助于了解补充氧气干预对 TRBF、DO2、MO2 和 OEF 结果的影响，以及不同持续时间的缺血。
