Oxygen distribution in the rabbit eye and oxygen consumption by the lens
Oxygen distribution in the rabbit eye and oxygen consumption by the lens
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DOI：
10.1167/iovs.05-1475
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发表时间：
2006-04-01
影响因子：
4.4
通讯作者：
Beebe, DC
中科院分区：
文献类型：
--
作者：
Shui, YB;Fu, JJ;Beebe, DC
目的.过度暴露于氧气中被认为是核性白内障的危险因素。为了更好地了解氧在眼内的代谢，绘制了氧在眼内液中的分布图，并计算了呼吸不同氧水平的兔眼透镜的耗氧率。将年轻的白化病兔麻醉、插管并暴露于常氧、低氧或高氧条件下。用脉搏血氧仪监测血液的血红蛋白饱和度，用血气分析仪测量动脉血氧水平。采用光导纤维氧传感器（光电管）测定夜间不同区域的氧含量。通过测量玻璃体腔内的氧梯度计算穿过透镜后部的氧通量。兔呼吸低氧或高氧空气时，眼液氧含量发生明显变化。在视网膜血管系统、虹膜血管系统和中央角膜的内表面附近氧含量最高。与邻近区域相比，最靠近睫状体的睫状体部和前房角附近的房水中的氧水平降低。氧气水平一般较低，更接近透镜。根据玻璃体中的氧梯度，计算出在常氧条件下透镜后半部分的氧消耗为0.2至0.4 μ L/h。透镜后部的耗氧量与供氧量成比例增加。眼内氧气主要来自视网膜和虹膜血管系统，并通过角膜扩散。新鲜分泌的房水和前房角中的房水相对耗尽氧气。当透镜暴露于增加的氧时，氧消耗的显著增加可能导致产生更高水平的活性氧，并且可能提供升高的氧水平与核性白内障风险之间的联系。
PURPOSE. Excessive exposure to oxygen has been proposed to be a risk factor for nuclear cataracts. For a better understanding of the metabolism of oxygen in the eye, oxygen distribution was mapped in the intraocular fluids, and the rate of oxygen consumption by the lens in rabbits breathing different levels of oxygen was calculated.METHODS. Young albino rabbits were anesthetized, intubated, and exposed to normoxic, hypoxic, or hyperoxic conditions. The hemoglobin saturation of the blood was monitored with a pulse oximeter, and arterial oxygen levels were measured with a blood gas analyzer. A fiberoptic optical oxygen sensor (optode) was Used to determine oxygen levels in different regions of the eve. Oxygen flux across the posterior of the lens was calculated from the measured oxygen gradients in the vitreous chamber.RESULTS. Oxygen levels in the ocular fluids changed markedly when rabbits breathed air made hypoxic or hyperoxic. Oxygen levels were highest near the retinal vasculature, the iris vasculature, and the inner surface of the central cornea. Compared with nearby regions, oxygen levels were decreased in the aqueous humor closest to the pars plicata of the ciliary body and near the anterior chamber angle. Oxygen levels were generatly lower closer to the lens. From the oxygen gradients in the vitreous body, oxygen consumption by the posterior half of the lens was calculated to be 0.2 to 0.4 mu L/h under normoxic conditions. Oxygen Consumption by the posterior of the lens increased in proportion to the amount of oxygen Supplied.CONCLUSIONS. Intraocular oxygen is mostly derived from the retinal and, iris vasculature and by diffusion across the cornea. Freshly secreted aqueous humor and the aqueous humor in the anterior chamber angle are relatively depleted of oxygen. The marked increase in oxygen consumption that Occurs when the lens is exposed to increased oxygen is likely to result in the production of higher levels of reactive oxygen species and may provide a link between elevated oxygen levels and the risk of nuclear cataracts.