Corneal transparency is dependent on regulation of the hydration of the corneal stroma. Water is driven into the cornea across the epithelial and endothelial cell layers by the stromal swelling pressure. This fluid leak into the cornea is counterbalanced by the corneal fluid pump, which is predominantly attributed to the ion and fluid transport capacity of the endothelial cell layer. Primary and secondary active transport mechanisms are responsible for generating a net ion flux from the stromal to anterior chamber side of the endothelium; however, the identity and location of all the components of this transport system are not known. The endothelial fluid pump is dependent on the presence of Cl(-) and HCO(3)(-), and can be slowed by carbonic anhydrase inhibitors. A number of anion transport mechanisms have been identified and characterized in the endothelium, including basolateral Na(+)/2HCO(3)(-) cotransport, Na(+)/K(+)/2Cl(-) cotransport, Cl(-)/HCO(3)(-) exchange, and apical anion channels permeable to both Cl(-) and HCO(3)(-). Furthermore, there is evidence for a carbonic anhydrase mediated CO(2)-diffusive mode of apical HCO(3)(-) flux. These findings are incorporated into a new model of transendothelial anion transport, which suggests that there are a number of alternate pathways for anion transport. There have been few studies on activation of signal transduction pathways that could stimulate endothelial fluid transport. Interestingly, recent studies show that multiple autocrine signaling pathways are in place that could be upregulated during physical stimulation and may be responsible for maintaining basal levels of fluid secretion.

中文翻译：

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角膜内皮中离子转运机制的鉴定和调控。

角膜透明性取决于角膜基质水合的调节。通过基质溶胀压力，水穿过上皮和内皮细胞层进入角膜。流体渗入角膜可通过角膜液泵来抵消，这主要归因于内皮细胞层的离子和流体传输能力。初级和次级主动转运机制负责产生从内皮的基质室到前房侧的净离子通量。但是，该运输系统所有组件的标识和位置尚不清楚。内皮液泵取决于Cl（-）和HCO（3）（-）的存在，并且可以被碳酸酐酶抑制剂减慢。在内皮中已鉴定并表征了许多阴离子转运机制，包括基底外侧Na（+）/ 2HCO（3）（-）共转运，Na（+）/ K（+）/ 2Cl（-）共转运，Cl（- ）/ HCO（3）（-）交换，以及可渗透Cl（-）和HCO（3）（-）的顶端阴离子通道。此外，有证据表明碳酸酐酶介导的顶HCO（3）（-）通量的CO（2）扩散模式。这些发现被并入了跨内皮阴离子转运的新模型，这表明阴离子转运有许多替代途径。关于激活刺激内皮液运输的信号转导途径的研究很少。有趣的是