ASCORBIC ACID

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 我们的数据表明，晶状体周围液体中的相对低氧对于保护晶状体免受最常见类型的年龄相关性白内障的伤害是重要的。玻璃体凝胶的破坏会导致晶状体暴露在氧气中的增加，并形成核性白内障。我们在接受视网膜手术的患者的眼睛中检测到氧气梯度，这预示着玻璃体肯定在消耗氧气。对玻璃体液中氧气消耗的直接测试证实了这一预测，并证明了这种影响独立于细胞代谢活动，并依赖于抗坏血酸。以前对兔的研究表明，抗坏血酸在房水中进入眼睛，滋养眼球前部结构(房水中的抗坏血酸浓度是血液中的20倍)。据认为，眼球后部的抗坏血酸是由房水扩散而来的。然而，与其他物种不同的是，人类在玻璃体体液(眼睛的后部)比(前部)房水中的抗坏血酸含量更高，这排除了水是人类玻璃体抗坏血酸的唯一来源。为了更好地了解抗坏血酸在眼睛中的分布，从而了解抗坏血酸的来源和汇，我们想要测量活体兔和人眼睛中的抗坏血酸梯度。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our data suggest that the relative hypoxia in the fluids around the lens is important to protect the lens against the most common type of age-related cataract. Destruction of the vitreous gel leads to increased exposure of the lens to oxygen and the formation of nuclear cataracts. We detected oxygen gradients in the eyes of patients undergoing retinal surgery that predicted that the vitreous body must be consuming oxygen. Direct tests of oxygen consumption in isolated vitreous humor confirmed this predication and demonstrated that this effect was independent of cellular metabolic activity and dependent on ascorbate. Previous studies in rabbits have suggested that ascorbate enters the eye in the aqueous humor that nourishes the structures of the anterior of the eye (ascorbate concentrations in aqueous humor are >20X greater than in the blood). It was believed that ascorbate in the posterior of the eye was derived by diffusion from the aqueous humor. However, unlike other species, humans have higher ascorbate in the vitreous humor (in the posterior of the eye) than in the (anterior) aqueous humor, ruling out the aqueous as the sole source of ascorbate for the human vitreous. To get a better idea of the ascorbate distribution in the eye and, therefore, the sources and sinks for ascorbate, we would like to measure ascorbate gradients in the eyes of living rabbits and humans.