Response of Inner Retinal Oxygen Extraction Fraction to Light Flicker Under Normoxia and Hypoxia in Rat
Response of Inner Retinal Oxygen Extraction Fraction to Light Flicker Under Normoxia and Hypoxia in Rat
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DOI：
10.1167/iovs.13-13811
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发表时间：
2014-09-01
影响因子：
4.4
通讯作者：
Shahidi, Mahnaz
中科院分区：
文献类型：
--
作者：
Teng, Pang-yu;Wanek, Justin;Shahidi, Mahnaz
目的.氧摄取分数（OEF），定义为氧代谢（MO 2）与输送（DO 2）的比率，决定了DO 2对MO 2的补偿水平。在本研究中，我们验证了一个假设，即在全身常氧和缺氧条件下，由于MO 2和DO 2的匹配，视网膜内OEF在光闪烁期间保持不变。用磷光寿命成像法测定10只大鼠视网膜血管氧分压（PO 2）。根据Fick原理，从血管PO 2中推导出视网膜内OEF。在全身常氧和缺氧条件下，在光闪烁之前和期间获得测量值。光闪烁和全身氧合对视网膜血管PO 2和OEF的影响用方差分析法（ANOVA）进行了分析。闪烁时视网膜静脉PO 2降低（P < 0.01，N = 10），而视网膜内OEF升高（P = 0.02）。缺氧时视网膜动、静脉PO 2降低（P < 0.01），OEF升高（P < 0.01）。OEF的交互作用不显著（P = 0.52），表明常氧和缺氧条件下OEF对闪烁光的反应相似。在光闪烁期间，OEF在常氧下从0.46 +/- 0.13增加到0.50 +/- 0.11，而在缺氧下，OEF从0.67 +/- 0.16增加到0.74 +/-0.14。在光闪烁期间，视网膜内OEF增加，表明在全身常氧和缺氧条件下，DO 2的相对变化小于MO 2。内视网膜OEF是一个潜在的有用参数，用于评估在生理和病理条件下MO 2和DO 2的相对变化。
PURPOSE. Oxygen extraction fraction (OEF), defined by the ratio of oxygen metabolism (MO2) to delivery (DO2), determines the level of compensation of MO2 by DO2. In the current study, we tested the hypothesis that inner retinal OEF remains unchanged during light flicker under systemic normoxia and hypoxia in rats due to the matching of MO2 and DO2.METHODS. Retinal vascular oxygen tension (PO2) measurements were obtained in 10 rats by phosphorescence lifetime imaging. Inner retinal OEF was derived from vascular PO2 based on Fick's principle. Measurements were obtained before and during light flicker under systemic normoxia and hypoxia. The effects of light flicker and systemic oxygenation on retinal vascular PO2 and OEF were determined by ANOVA.RESULTS. During light flicker, retinal venous PO2 decreased (P < 0.01, N = 10), while inner retinal OEF increased (P = 0.02). Under hypoxia, retinal arterial and venous PO2 decreased (P < 0.01), while OEF increased (P < 0.01). The interaction effect was not significant on OEF (P = 0.52), indicating the responses of OEF to light flicker were similar under normoxia and hypoxia. During light flicker, OEF increased from 0.46 +/- 0.13 to 0.50 +/- 0.11 under normoxia, while under hypoxia, OEF increased from 0.67 +/- 0.16 to 0.74 +/- 0.14.CONCLUSIONS. Inner retinal OEF increased during light flicker, indicating the relative change in DO2 is less than that in MO2 in rats under systemic normoxia and hypoxia. Inner retinal OEF is a potentially useful parameter for assessment of the relative changes of MO2 and DO2 under physiologic and pathologic conditions.