ASCORBIC ACID

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 我们的数据表明，透镜周围液体中的相对缺氧对于保护透镜免受最常见类型的年龄相关性白内障的影响是重要的。玻璃体凝胶的破坏导致透镜暴露于氧气的增加和核性白内障的形成。我们检测了接受视网膜手术的患者眼中的氧梯度，预测玻璃体必须消耗氧气。在离体玻璃体液中的耗氧量的直接测试证实了这一预测，并表明这种效果是独立的细胞代谢活性和依赖于抗坏血酸。先前在兔子中的研究表明，抗坏血酸盐通过水状体进入眼睛，水状体覆盖眼睛前部的结构（水状体中的抗坏血酸盐浓度比血液中的高> 20倍）。据信，眼后部的抗坏血酸盐是通过从房水扩散而获得的。然而，与其他物种不同，人类在玻璃体液（在眼睛后部）中具有比在（前部）房水中更高的抗坏血酸盐，排除了房水作为人类玻璃体的抗坏血酸盐的唯一来源。为了更好地了解抗坏血酸在眼睛中的分布，以及抗坏血酸的来源和吸收，我们想测量活体兔子和人类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.