血管内皮上皮细胞钠通道（ENaC）在盐敏感性高血压中作用及机制研究

The epithelial sodium channel (ENaC) mediates Na+ absorption across epithelial cells in the kidney collecting duct, lung, distal colon, and sweat duct. Na+ transport is critical for the maintenance of Na+ homeostasis and thus plays a critical role in maintenance of salt balance and systemic blood pressure. In our recent work, we find the expression of ENaC in rat small-diameter mesenteric arteries (SDMAs); Patch-clamp experiments demonstrated that primary cultured mesenteric artery endothelial cells expressed amiloride-sensitive sodium currents; the expression and activity of ENaC in SDMAs are significantly changed after high salt intake, which is followed the blood pressure alteration. Therefore, this subject hypothesized that the endothelial cells ENaC may play an important role in salt-sensitive hypertension through regulation of vasodilation by nitric oxide. In this study, we will detect the mechanism that endothelium ENaC involved in salt-sensitive hypertension from two aspects of aldosterone and endothlium oxidation in vitro and in vivo by the technology of patch clamp, immunofluorescence, western blot and vascular function test. We will carry out this program using salt-sensitive and salt-resistant Sprague Dawle rat. We put forward a new point-of-view that endothlial cells ENaC is involved in salt-sensitive hypertension denpended on its ability to regulate vascular function. This new view will provide a new strategy for prevention and treatment of salt-sensitive hypertension.

上皮细胞钠通道（ENaC）在维持体内钠离子的动态平衡和控制系统血压起到重要作用。我们在前期工作中发现ENaC在成年大鼠肠系膜动脉内皮细胞表达，并在剖开的肠系膜动脉内皮进行膜片钳检测时，发现与经典的ENaC生物物理学特征一致的单通道电流，并发现ENaC表达水平及活性在高盐饲养时，随着血压的升高而变化。因此，我们提出假设，高盐摄入可引起醛固酮信号异常和/或氧化应激诱导血管内皮细胞ENaC的表达水平和活性改变，进而影响内皮细胞内钠水平和NO合成/释放，从而影响血管功能，最终导致盐敏感性高血压的发生。我们拟采用体内高盐模型观察血管内皮细胞ENaC表达分布及活性的变化规律；通过电生理学、分子生物学、激光共聚焦成像和血管功能学等方法验证上述科学假设并阐明其机制。本项目首次探讨血管内皮细胞ENaC在盐敏感性高血压的调节作用，为盐敏感性高血压的发生机制提供新的理论依据。

寻找调节盐敏感性高血压的关键因素对临床防治高血压具有重要意义。上皮钠通道（ENaC）在血管内皮中表达，并且在高盐饮食刺激后活性升高。我们假设血管内皮ENaC活性升高参与高盐诱导的血管功能紊乱，并在盐敏感性高血压发生发展中具有重要调节作用。本课题发现如下：1. 在正常SD大鼠中，高盐饲养可引起大鼠血清醛固酮水平下降，从而抑制血管内皮ENaC的表达和活性，进而改善血管的内皮依赖性舒张反应，从而减缓高盐诱导的SD大鼠血压升高（结果发表于British J Pharmacology, IF: 5.259）；2. 发现高盐孵育血管内皮细胞可抑制AMPK活性而上调ENaC通道活性和表达，从而抑制血管内皮的一氧化氮水平，进而调节血管功能，这可能是高盐上调血管内皮ENaC的可能机制（结果发表于Oxidative Medicine and Cellular Longevity，IF: 4.492）；3. 高盐饲养可显著升高SS大鼠血压，引起高血压症，机制为：高盐诱导SS大鼠血清醛固酮水平升高，从而上调血管内皮ENaC的表达和活性，引起eNOS活性和NO水平下降，进而损害血管的内皮依赖性舒张反应，从而诱导SS大鼠发生高血压。这可能与SS大鼠缺乏对高盐的反馈调节有关（相关结果投稿British J Pharmacology）。我们的研究结果为防治盐敏感性高血压开拓了新的研究方向。本项目相关研究成果发表了两篇SCI论文，一篇正在改稿，培养了研究生4名。