玻璃体的凝胶状态与抗坏血酸依赖性氧消耗：与核性白内障病因的关系。
The gel state of the vitreous and ascorbate-dependent oxygen consumption: relationship to the etiology of nuclear cataracts.
作者信息
Shui Ying-Bo, Holekamp Nancy M, Kramer Benjamin C, Crowley Jan R, Wilkins Mark A, Chu Fred, Malone Paula E, Mangers Shayna J, Hou Joshua H, Siegfried Carla J, Beebe David C
机构信息
Department of Ophthalmology and Visual Sciences, Washington University, St Louis, Missouri 63110, USA.
出版信息
Arch Ophthalmol. 2009 Apr;127(4):475-82. doi: 10.1001/archophthalmol.2008.621.
OBJECTIVE
To investigate the rate and mechanism of oxygen consumption by the vitreous.
METHODS
Oxygen consumption was measured with a microrespirometer. Vitreous ascorbate was measured spectrophotometrically and by gas chromatography-mass spectrometry. Vitreous degeneration was related to the rate of oxygen consumption and ascorbate concentration in samples obtained during vitrectomy.
RESULTS
Prolonged exposure to oxygen or treatment with ascorbate oxidase eliminated oxygen consumption by the vitreous. Adding ascorbate restored oxygen consumption. Oxygen consumption persisted after boiling or treating the vitreous with the chelating agents EDTA and deferoxamine. In patients undergoing retinal surgery, liquefaction of the vitreous and previous vitrectomy were associated with decreased ascorbate concentration and lower oxygen consumption.
CONCLUSIONS
Ascorbate in the vitreous decreases exposure of the lens to oxygen. The catalyst for this reaction is not known, although free iron may contribute. The gel state of the vitreous preserves ascorbate levels, thereby sustaining oxygen consumption. Vitrectomy or advanced vitreous degeneration may increase exposure of the lens to oxygen, promoting the progression of nuclear cataracts.
CLINICAL RELEVANCE
Determining how the eye is protected from nuclear cataracts should suggest treatments to reduce their incidence.
目的
研究玻璃体的耗氧速率及机制。
方法
使用微量呼吸计测量耗氧量。采用分光光度法以及气相色谱 - 质谱联用技术测量玻璃体中的抗坏血酸。将玻璃体变性与玻璃体切割术中获取的样本的耗氧速率和抗坏血酸浓度相关联。
结果
长时间暴露于氧气或用抗坏血酸氧化酶处理可消除玻璃体的耗氧。添加抗坏血酸可恢复耗氧。玻璃体经煮沸或用螯合剂乙二胺四乙酸（EDTA）和去铁胺处理后，耗氧持续存在。在接受视网膜手术的患者中，玻璃体液化和既往玻璃体切割术与抗坏血酸浓度降低及耗氧量减少相关。
结论
玻璃体中的抗坏血酸可减少晶状体对氧气的暴露。尽管游离铁可能起作用，但该反应的催化剂尚不清楚。玻璃体的凝胶状态可维持抗坏血酸水平，从而维持耗氧。玻璃体切割术或严重的玻璃体变性可能增加晶状体对氧气的暴露，促进核性白内障的进展。
临床意义
确定眼睛如何免受核性白内障的影响应能提示降低其发病率的治疗方法。
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