Arginine Uptake Mechanisms Regulate Nitric Oxide in the Renal Vasculature

描述（由申请人提供）：一氧化氮（NO）通过影响全身血管阻力以及体液和电解质稳态来调节动脉血压和肾功能。尽管对此课题进行了大量研究，但调节肾脏 NO 产生的重要因素尚未明确。我们实验室之前的工作证明了肾上皮细胞中 L-精氨酸 (L-Arg) 摄取机制的重要性。我们实验室令人兴奋的新结果表明，细胞摄取 L-Arg（NO 合酶的底物）也是肾血管内皮细胞中 NO 产生的关键调节剂。因此，L-Arg 摄取也是肾血管阻力的重要调节剂，从而对肾脏排泄功能产生影响。将提出的新数据表明 L-Arg 转运机制对肾血管系统中 NO 的产生和 NO 依赖性功能具有重要影响。使用这些新数据作为基本原理和独特的综合实验方法，我们将定义 L-Arg 转运蛋白在体外和体内调节肾血管功能中的作用，以了解这种 NO 产生的生理调节剂的重要性。实验将检验一般假设，即肾血管内皮细胞中 y 和 y L 转运蛋白对细胞 L-精氨酸的摄取通过改变体内 NOS 底物的可用性来介导 NO 的产生，并在肾功能以及液体和电解质稳态的调节中发挥关键作用。这一假设将通过三个具体目标来解决。具体目标 1 将利用独特的细胞和分子技术来识别肾血管中的 L-Arg 摄取机制和转运蛋白。目标 2 将采用新颖的方法来确定肾脉管系统中这些转运蛋白对正常和患病动物的体外和体内 NO 产生和 NO 依赖性功能的功能重要性。目标 3 中的实验将利用基因操纵小鼠来确定哪种 NOS 异构体受到细胞 L-Arg 摄取机制的影响。这种新颖的实验方法组合将用于阐明L-Arg转运在肾血管阻力和肾功能调节中的重要作用。这些研究的结果可能为了解高血压和血管相关并发症的原因提供重要见解，而高血压和血管相关并发症是美国死亡和发病的主要原因。

DESCRIPTION (provided by applicant): Nitric oxide (NO) regulates arterial blood pressure and kidney function by influencing systemic vascular resistance and fluid and electrolyte homeostasis. Despite the large amount of research on this subject, the factors important in the regulation of NO production in the kidney have not been clearly defined. Previous work from our laboratory demonstrated the importance of L-Arginine (L-Arg) uptake mechanisms in renal epithelial cells. Exciting new results from our laboratory indicate that cellular uptake of L-Arg, the substrate for NO synthase, is also a critical modulator of NO production in renal vascular endothelial cells. L-Arg uptake is therefore also an important regulator of renal vascular resistance with resulting effects on kidney excretory function. New data will be presented indicating that mechanisms of L-Arg transport have important effects on NO production and NO-dependent function in the renal vasculature. Using these novel data as a rationale and a unique integrative experimental approach, we will define the role of the L-Arg transporters in the regulation of renal vascular function in vitro and in vivo to provide an understanding of the importance of this physiological regulator of NO production. Experiments will test the General Hypothesis that cellular L-arginine uptake by y+ and y+L transporters in endothelial cells of the renal vasculature mediates the production of NO by altering the availability of NOS substrate in vivo and plays a critical role in the regulation of renal function as well as fluid and electrolyte homeostasis. This hypothesis will be addressed in three specific aims. Specific Aim 1 will utilize unique cellular and molecular techniques to identify the L-Arg uptake mechanisms and transporters in renal blood vessels. Aim 2 will employ novel methodology to determine the functional importance of these transporters in the renal vasculature on NO production and NO-dependent function both in vitro and in vivo in normal and diseased animals. Experiments in Aim 3 will then make use of genetically manipulated mice to determine which NOS isoform is affected by cellular L-Arg uptake mechanisms. This novel combination of experimental methods will be used to elucidate the important role of L-Arg transport in the regulation of renal vascular resistance and kidney function. The results of these studies may provide important insight into the causes of hypertension and vascular-related complications that are a leading cause of death and morbidity in the US.