Centre for Ophthalmology and Visual Science, Lions Eye Institute, The University of Western Australia, Perth, Western Australia, Australia.
Adv Exp Med Biol. 2018;1072:241-244. doi: 10.1007/978-3-319-91287-5_38.
The oxygen supply to the retina in man and most mammals is derived from both the retinal and choroidal circulations. However, some mammals have only a partially vascularized retina, and some have a completely avascular retina. Here we contrast the retinal oxygen levels during systemic hyperoxia in a fully vascularized retina (rat), a partially vascularized retina (rabbit), and an avascular retina (guinea pig). Oxygen sensitive microelectrodes were used to measure the intraretinal oxygen distribution in anaesthetized rats, rabbits and guinea pigs during air breathing and 100% oxygen ventilation. In the vascularized rat retina the increase in oxygen tension in the choroid, reflected the increase in systemic oxygen levels during hyperoxic ventilation. However, the rise in oxygen levels in the inner retina was muted. In the avascular region of the partially vascularized rabbit retina, the increase in choroidal oxygen tension resulted in a large increase in oxygen tension across the full thickness of the retina. In the avascular retina of the guinea pig, very little change in choroidal or retinal oxygen tension was seen during systemic hyperoxia. Remarkably different responses to systemic hyperoxia are evident in the rat, rabbit, and guinea pig, three conventional laboratory animals that are commonly used in ophthalmic research. Neither the regulatory mechanisms responsible for the increase in oxygen consumption in the rat retina, or the stability of the choroidal oxygen tension in the guinea pig during systemic hyperoxia are currently understood. A better understanding of oxygen regulation in the mammalian retina could open up new avenues for improving the oxygen environment in the human retina in a range of ischaemic retinal diseases that account for the majority of blindness in the developed world.
人和大多数哺乳动物的视网膜供氧来自视网膜和脉络膜循环。然而，有些哺乳动物的视网膜只有部分血管化，有些则完全没有血管。在这里，我们对比了在完全血管化的视网膜（大鼠）、部分血管化的视网膜（兔）和无血管的视网膜（豚鼠）中，全身高氧血症期间视网膜的氧水平。在麻醉的大鼠、兔和豚鼠中，使用氧敏感微电极测量空气呼吸和 100% 氧气通气期间的视网膜内氧分布。在血管化的大鼠视网膜中，脉络膜氧张力的增加反映了高氧通气期间全身氧水平的增加。然而，内视网膜的氧水平上升幅度较小。在部分血管化兔视网膜的无血管区域，脉络膜氧张力的增加导致整个视网膜厚度的氧张力大幅增加。在豚鼠的无血管视网膜中，在全身高氧血症期间，脉络膜或视网膜氧张力几乎没有变化。大鼠、兔和豚鼠这三种常用于眼科研究的常规实验室动物对全身高氧血症的反应明显不同。目前还不清楚导致大鼠视网膜耗氧量增加的调节机制，或豚鼠在全身高氧血症期间脉络膜氧张力的稳定性。对哺乳动物视网膜氧调节的更好理解可能为改善包括发达国家大多数失明在内的多种缺血性视网膜疾病中人类视网膜的氧环境开辟新途径。
