Effects of light and darkness on oxygen distribution and consumption in the cat retina.
Effects of light and darkness on oxygen distribution and consumption in the cat retina.
复制标题
光与黑暗对猫视网膜中氧分布和消耗的影响。
DOI：
10.1085/jgp.88.4.521
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发表时间：
1986-10
影响因子：
3.8
通讯作者：
Linsenmeier, R A
中科院分区：
文献类型：
--
作者：
Linsenmeier, R A
这些实验是为了研究光和暗对麻醉猫视网膜氧合的影响。测量是用双管氧微电极进行的，能够记录氧张力（PO2）和局部电压。漫射白光照射到适应黑暗的视网膜，导致视网膜外半部PO2增加高达30 mmHg。在大约75%深度处变化最大，与外核层相对应。内视网膜PO2未见改变或降低。光诱发的视网膜外PO2的增加随光照的持续时间和强度而分级，并在60 s的视杆饱和光照时达到最大。对于这些刺激，光照开始时PO2的增加（平均半时间12.2 s）比光照结束时的恢复（平均半时间5.9 s）要慢，但对于高于杆饱和的刺激，PO2的恢复要慢得多。在电极穿透和拔出以及光和暗适应过程中测量了PO2的分布。暗适应剖面的特征是在65-85%深度处PO2最小值接近0 mmHg，并且从最小值到脉络膜有一个陡峭的梯度。在光杆饱和的光适应过程中，视网膜外半部的PO2升高，最小值被消除。将这些轮廓与氧气扩散的一维模型拟合表明，光将外层视网膜的氧气消耗降低到其黑暗适应值的约50%。
These experiments were done to investigate the effects of light and darkness on the oxygenation of the retina in anesthetized cats. Measurements were made with double-barreled oxygen microelectrodes capable of recording both oxygen tension (PO2) and local voltages. Diffuse white illumination presented to a dark-adapted retina led to an increase in PO2 of up to 30 mmHg in the outer half of the retina. Changes were maximal at approximately 75% depth, corresponding to the outer nuclear layer. No change or decrease in PO2 was observed in the inner retina. Light-evoked increases in outer retinal PO2 were graded with the duration and strength of illumination, and were maximal in response to 60 s of illumination at rod saturation. For these stimuli, the increase at the onset of illumination was slower (average half- time, 12.2 s) than the recovery at the end of illumination (average half-time, 5.9 s), but for stimuli above rod saturation, PO2 recovered much more slowly. The profile of PO2 was measured during electrode penetration and withdrawal and during light and dark adaptation. Dark- adapted profiles were characterized by a minimum PO2 of nearly 0 mmHg at depths of 65-85%, and a steep gradient from the minimum to the choroid. During light adaptation at rod saturation, PO2 was elevated in the outer half of the retina and the minimum was eliminated. Fits of the profiles to a one-dimensional model of oxygen diffusion indicated that light reduced the oxygen consumption of the outer retina to approximately 50% of its dark-adapted value.