Spatially resolved measurements of retinal metabolism

摘要 详细了解视网膜代谢是了解视网膜如何承受，补偿， 或遭受系统变化和疾病所带来的压力。这个应用程序需要一个新的 了解哺乳动物视网膜糖酵解和氧化代谢的方法，通过记录空间 在离体大鼠和小鼠视网膜与微电极的氧和pH的分布，使用数学 扩散模型，以提取关于基质利用率和废物产生率的信息，以及 利用药理学来分离不同的过程。该策略是对先前体内和 在体外方法，但允许在内部和外部视网膜的代谢事件的分离，这很少 这是可能的，不能用整个组织代谢的测量来完成。微电极 这些方法同时允许记录经视网膜和视网膜内的视网膜电图 功能有三个目标。1)将记录氧气的深度分布，以便定量确定 离体视网膜的代谢与体内视网膜的代谢相比如何，以及内层视网膜和外层视网膜的区别 新陈代谢。已知光感受器执行高速率的（无氧）糖酵解，但平衡 氧化和糖酵解能量产生之间的关系尚不清楚，在视网膜内层，这是否会改变， 取决于葡萄糖的供应。视网膜血流量增加响应闪烁的光（神经血管 耦合），但驱动这一点的内部视网膜中代谢变化的大小是未知的，并且将 在这里测量。2)通过记录离体视网膜中pH值的深度分布， 量化。糖酵解和氧化代谢在产酸过程中有很大的不同。识别 抑制糖酵解或氧化的酸产生、缺氧和代谢毒物的成分 代谢将被使用。3)在某些组织中，有证据表明糖酵解和氧化代谢是 将乳酸和/或丙酮酸从糖酵解活性细胞转移到 更依赖于氧化代谢。这个概念导致了视网膜使用类似策略的想法， 乳酸在穆勒细胞中产生并穿梭于神经元。相对较新的可用性 单羧酸转运的选择性阻断剂，提供了一个机会，以评估这种重要性， 在内层和外层视网膜中定量转移。所有要获得的信息对于 了解视网膜在疾病中的变化，以及内层和外层视网膜的功能 氧化和糖酵解代谢。

Abstract Understanding retinal metabolism in detail is fundamental to knowing how the retina withstands, compensates for, or suffers from the stresses imposed by systemic changes and disease. This application takes a new approach to understanding glycolytic and oxidative metabolism of the mammalian retina, by recording spatial profiles of oxygen and pH in the isolated rat and mouse retina with microelectrodes, using mathematical models of diffusion to extract information about rates of substrate utilization and waste generation, and employing pharmacology to isolate different processes. This strategy is complimentary to previous in vivo and in vitro approaches, but allows a separation of metabolic events in the inner and outer retina, which has rarely been possible, and cannot be done with measurements of whole tissue metabolism. Microelectrode approaches simultaneously allow recording of transretinal and intraretinal electroretinograms to monitor retinal function. There are three aims. 1) Depth profiles of oxygen will be recorded in order to determine quantitatively how the metabolism of the isolated retina compares to that in vivo, and how the inner and outer retina differ metabolically. Photoreceptors are known to perform high rates of (anaerobic) glycolysis, but the balance between oxidative and glycolytic energy production is not known in the inner retina, and whether this changes depending on glucose supply. Retinal blood flow increases in response to flickering light (neurovascular coupling), but the size of the metabolic change in the inner retina that drives this is unknown, and will be measured here. 2) By recording depth profiles of pH in the isolated retina, the production of acidic waste will be quantified. Glycolysis and oxidative metabolism are very different in acid production. To identify the components of acid production, hypoxia and metabolic poisons that suppress either glycolysis or oxidative metabolism will be used. 3) In some tissues there is evidence that glycolysis and oxidative metabolism are compartmentalized, with a transfer of lactate and/or pyruvate from glycolytically active cells to ones that depend more on oxidative metabolism. This concept has led to the idea that the retina uses a similar strategy, with lactate being produced in Muller cells and shuttled to neurons. The relatively recent availability of selective blockers of monocarboxylate transport, provides an opportunity to evaluate the importance of such transfer quantitatively in both the inner and outer retina. All the information to be gained is fundamental to understanding how the retina changes in disease, and what the capabilities of the inner and outer retina are for oxidative and glycolytic metabolism under different conditions.