Epoxyeicosatrienoic Acids Regulate Na Transport in CCD

皮质集合管（CCD）负责钠离子重吸收的调节。的Na CCD中的转运是一个两步过程：Na通过细胞膜穿过顶膜进入细胞。 上皮Na通道（ENaC），Na通过Na-K-ATP酶被挤出穿过基底外侧膜。 顶端Na电导是CCD中Na重吸收的限速步骤。此外，Na 由于Na的转运是一种产电的过程，因此Na的转运速率也受细胞膜电位的影响。 过程因此，通过改变基底外侧K通道活性来改变细胞膜电位， 影响CCD中Na的转运。我们的初步数据表明，花生四烯酸（AA）抑制 ENaC和基底外侧钾通道活性以及AA对ENaC和基底外侧钾通道活性的影响 通道通过阻断AA的表氧化酶依赖性代谢而消除。还有11，12 环氧二十碳三烯酸（EET）是CYP-环氧合酶-依赖性AA代谢产物， AA对ENaC影响。因此，我们将测试EET通过抑制Na转运来抑制Na转运的假设。 EET的抑制作用是由ENaC和基底外侧K通道在CCD和EET的抑制作用增强的高浓度 纳摄入量。 具体目标1：检测Na摄入通过改变Na+浓度来调节AA对ENaC的抑制作用 EET还参与介导ENaC的反馈调节。 具体目的2：检验AA的CYP-表氧化酶依赖性代谢物抑制 基底外侧的K通道。 具体目的3：检验腺苷受体的刺激抑制ENaC和ENaC的假设。 CCD中的基底外侧K通道通过CYP-环氧合酶依赖性AA代谢物。 具体目标4：检验EET与其他细胞信号传导途径的相互作用是 参与EET对ENaC的影响。

The cortical collecting duct (CCD) is responsible for the hormone-regulated Na reabsorption. The Na transport in the CCD is a two-step process:Na enters the cell across the apical membrane through the epithelial Na channel (ENaC) and Na is extruded across the basolateral membrane via Na-K-ATPase. Apical Na conductance is a rate limiting step for the Na reabsorption in the CCD. In addition, the Na transport rate is also affected by the cell membrane potential because the Na transport is an electrogenic process. Thus, an alteration in cell membrane potential by changing basolateral K channel activity should affect Na transport in the CCD. Our preliminary data have demonstrated that arachidonic acid (AA) inhibits the activity of ENaC and the basolateral K channels and that the effect of AA on ENaC and basolateral K channels is abolished by blocking CYP epoxygenase-dependent metabolism of AA. Also, 11,12 epoxyeicosatrienoic acid (EET), a product of CYP-epoxygenase-dependet AA metabolite, mimic the effect of AA on ENaC. Thus, we will test the hypothesis that EET suppresses Na transport by inhibiting ENaC and basolateral K channels in the CCD and that the inhibitory effect of EET is enhanced by a high Na intake. Specific Aim 1: To test that Na intake modulates the inhibitory effect of AA on ENaC by changing CYP Epoxygenase activity and that EET also is involved in mediating the feedback-regulation of ENaC. Specific Aim 2: To test the hypothesis that CYP-epoxygenase dependent metabolites of AA inhibit basolateral K channels in the CCD. Specific Aim 3: To test the hypothesis that stimulation of adenosine receptor inhibits ENaC and the basolateral K channels in the CCD via CYP-epoxygenase dependent AA metabolites. Specific Aim 4: To test the hypothesis that the interaction of EET with other cell signaling pathways is involved in mediatina the effect of EET on ENaC.