This review summarizes the existing information on the concentration of H+ (pH) in vertebrate retinae and its changes due to various reasons. Special features of H+ homeostasis that make it different from other ions will be discussed, particularly metabolic production of H+ and buffering. The transretinal distribution of extracellular H+ concentration ([H+]o) and its changes under illumination and other conditions will be described in detail, since [H+]o is more intensively investigated than intracellular pH. In vertebrate retinae, the highest [H+]o occurs in the inner part of the outer nuclear layer, and decreases toward the RPE, reaching the blood level on the apical side of the RPE. [H+]o falls toward the vitreous as well, but less, so that the inner retina is acidic to the vitreous. Light leads to complex changes with both electrogenic and metabolic origins, culminating in alkalinization. There is a rhythm of [H+]o with H+ being higher during circadian night. Extracellular pH can potentially be used as a signal in intercellular volume transmission, but evidence is against pH as a normal controller of fluid transport across the RPE or as a horizontal cell feedback signal. Pathological and experimentally created conditions (systemic metabolic acidosis, hypoxia and ischemia, vascular occlusion, excess glucose and diabetes, genetic disorders, and blockade of carbonic anhydrase) disturb H+ homeostasis, mostly producing retinal acidosis, with consequences for retinal blood flow, metabolism and function.

中文翻译：

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脊椎动物视网膜的 pH 值及其自然发生和病理变化


本文总结了脊椎动物视网膜中 H+ （pH） 浓度及其因各种原因而发生的变化的现有信息。将讨论 H+ 稳态与其他离子不同的特殊特征，特别是 H+ 的代谢产生和缓冲。将详细描述细胞外 H + 浓度 （[H + ] o） 的跨视网膜分布及其在照明和其他条件下的变化，因为 [H + ] o 比细胞内 pH 值更深入研究。在脊椎动物视网膜中，最高的 [H+]o 出现在外核层的内部，并向 RPE 降低，达到 RPE 顶端的血液水平。[H+]o 也向玻璃体下降，但较小，因此视网膜内侧对玻璃体呈酸性。光会导致电源和代谢起源的复杂变化，最终导致碱化。有一个 [H+]o 的节律，H+ 在昼夜节律中较高。细胞外 pH 值可能用作细胞间体积传递的信号，但有证据表明 pH 值不是液体通过 RPE 转运的正常控制器或作为水平细胞反馈信号。病理和实验产生的条件（全身性代谢性酸中毒、缺氧和缺血、血管阻塞、血糖过高和糖尿病、遗传疾病和碳酸酐酶阻断）扰乱 H+ 稳态，主要产生视网膜酸中毒，对视网膜血流、新陈代谢和功能产生影响。