BLOOD-LENS TRANSFER OF GLUTATHIONE & SULFUR AMINO ACIDS

谷胱甘肽的血晶状体转移

• 批准号: 2163022
• 负责人: Berislav V Zlokovic
• 金额: $ 16.45万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-08-01 至 1996-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2163022
• 关键词: aminoacid transport; biological transport; blood aqueous barrier; eye circulation; glutathione; guinea pigs; high performance liquid chromatography; lens; perfusion; radiotracer; sulfur aminoacid

Lens transparency is essential for proper visual function. Glutathione (GSH) plays an important role in preventing lens opacification (cataract) by maintaining SH-groups of the lens proteins (membrane components, enzymes and crystallins) in reduced state. The lens is rich in GSH, and the current concept states that low levels of GSH are not consistent with lens clarity, but themselves are cataract inducing. Uptake of GSH by the lens and GSH lens synthesis de novo from sulfur amino acids (SAA) have been demonstrated in vitro, but direct evidence is lacking to conclude that this approximates the situation invivo. A new invivo vascular eye perfusion (VEP) model in the guinea-pig has been developed in our laboratory. The use of this species as an animal model for proposed studies has been justified during the course of our preliminary work. Biochemical characterization of guinea-pig lens suggested that metabolic scheme for GSH homeostasis is similar to that in other mammalian lenses. Using present VEP model, we obtained strong preliminary evidence indicating significant insitu rapid cellular uptake of newly secreted plasma-derived [35S]-GSH by the lens. A rapid in situ GSH lens synthesis from newly secreted blood-borne (35S)-cysteine was shown by radio HPLC analysis. The focus of this proposal is directed at plasma-derived GSH and SAA in the lens. The proposal is designed to test in a comprehensive fashion the hypothesis that blood-to-lens transport of circulating GSH and SAA is essential for the regulation of GSH levels in normal lenses. Towards this end, several experiments are proposed to test the following two hypotheses: I. Plasma-derived GSH is rapidly taken up at the lenticular epithelium by a specific transport system. II. GSH lens synthesis de novo is dependent on blood-to-lens transport of SAA. All transport and metabolic studies in normal guinea-pigs will use the VEP model, and consider for kinetic analysis four eye compartments including plasma, aqueous humor, lens capsule/epithelium and lens/cortex. Molecular forms of uptake during compartmental blood-to-lens transfer will be determined by radio-HPLC. The specificity and kinetic properties of GSH transport system in the lens will be characterized in situ, and GSH de novo synthesis from circulating SAA precursors will be estimated. These studies will help us understand the significance of blood-to-lens transport of GSH and SAA for normal lens function. Defining the role of plasma-derived GSH and SAA in normal lenses may be important in designing therapeutic strategies to decelerate cataract-inducing processes and/or to prevent formation of cataract.

晶状体透明度对于正常的视觉功能是必不可少的。谷胱甘肽 (GSH)在预防晶状体混浊(白内障)中起着重要作用 通过维持晶状体蛋白的SH基团(膜组件， 酶和晶体蛋白)处于还原状态。晶状体富含谷胱甘肽，而且 目前的概念认为，低水平的GSH与 晶状体清澈，但本身就是诱发白内障的原因。人体摄取谷胱甘肽 含硫氨基酸(SAA)合成晶状体和GSH晶状体 已经在体外得到证实，但缺乏直接证据来得出结论 这与Vivo的情况很接近。一种新的活体血管眼 建立了豚鼠脑血流灌注(VEP)模型。 实验室。使用该物种作为建议的动物模型 在我们的前期工作过程中，研究是合理的。 豚鼠晶状体的生化特征表明代谢 GSH动态平衡的方案与其他哺乳动物的晶状体相似。 使用目前的VEP模型，我们获得了强有力的初步证据 表明新分泌的细胞在原位快速摄取 晶状体中血浆衍生的[35S]-GSH。一种快速原位合成GSH晶状体的方法 从新分泌的血源(~(35)S)-半胱氨酸用放射高效液相色谱显示 分析。这项提案的重点是针对血浆来源的GSH和 镜头里的萨阿。该提案旨在通过全面的 形成一种假说，循环中的GSH和GSH的血液到晶状体的运输 SAA对于调节正常晶状体中的GSH水平是必不可少的。 为此，建议进行几个实验来测试以下内容 两个假说：一、血浆来源的谷胱甘肽在 豆状上皮通过特定的运输系统。二、谷胱甘肽晶状体 SAA的合成依赖于血到晶状体的转运。全 正常豚鼠的运输和代谢研究将使用VEP 模型，并考虑用于运动分析的四个眼舱，包括 血浆、房水、晶状体囊/上皮和晶状体/皮质。分子 间隔性血液到晶状体转移过程中摄取的形式如下 用放射高效液相色谱仪测定。谷胱甘肽的专一性和动力学性质 在晶状体转运系统中会进行原位表征，而谷胱甘肽 将估计循环SAA前体的Novo合成。这些 研究将帮助我们理解血液到晶状体的重要性 正常晶状体功能所需的GSH和SAA转运。定义的角色 正常晶状体中血浆来源的GSH和SAA在设计中可能是重要的 减慢白内障诱发过程的治疗策略和/或 预防白内障的形成。