ENDOTHELIN CONTROL OF RENAL HEMODYNAMIC AND EXCRETORY FUNCTION

盐敏感性或盐依赖性血压升高在大多数人群中是明显的。控制钠排泄的肾缺陷是导致盐依赖性高血压的主要原因。每位项目负责人在过去10年的工作提供了关于肾内皮素（ET- 1）系统在控制钠排泄、肾脏血流动力学和血压方面的强大作用的重要信息，表明内皮素系统在生理意义上可与肾素-血管紧张素系统相媲美。这包括重要的证据表明，高盐饮食，即使没有高血压，对肾脏血流动力学功能有显著影响。我们的研究使我们假设，ETB受体的功能是对ETA受体强大的血管收缩和高血压作用的一种平衡。然而，关于决定这些受体系统活性的具体条件，根本没有足够的信息。目前的建议是基于研究表明，ETA受体在促进高血压和相关的终末器官损伤中起作用，而缺乏ETB受体功能会导致对盐诱导高血压的敏感性增加。因此，当前项目的目标是通过从基因水平到全动物模型的一系列实验方法来确定ET-1的生理作用，以全面探索肾脏中调节ET-1活性的途径。

Salt-sensitivity or salt-dependent elevations in blood pressure are evident in a majority of the human population. Renal defects in the control of sodium excretion are known to be major contributors to the development of salt-dependent hypertension. Work conducted by each of the Project Leaders over the past 10 years has provided important Information about the powerful role of the renal endothelin (ET- 1) system in the control of sodium excretion, renal hemodynamics, and blood pressure indicating that the endothelin system rivals the renin-angiotensin system in physiological significance. This includes important evidence that a high salt diet, even without hypertension, has a significant influence on renal hemodynamic function. Our studies have led us to hypothesize that the ETB receptor functions as a counter-balance to the powerful vasoconstrictor and pro-hypertensive actions of the ETA receptor. However, there is simply not enough information available about the specific conditions that determine the activity of these receptor systems. The current proposal builds on studies demonstrating that the ETA receptor plays a role in promoting hypertension and associated end-organ damage while a lack of ETB receptor function results in increased sensitivity to salt-induced hypertension. Therefore, the goal of the current Program Project is to determine the physiological actions of ET-1 using an array of experimental approaches ranging from the gene level to whole animal models to comprehensively explore the pathways regulating ET-1 activity in the kidney. The current Program is made of four Projects. Each project explores a unique aspect of the endothelin system in terms of both hemodynamics and tubular function and will elucidate the receptor subtype specific actions on inflammation, oxidative stress, renal hemodynamics and tubular function; a particular emphasis is on factors that influence the control of sodium excretion and blood pressure. These studies are expected to provide important new insight into a major system that regulates renal sodium excretion. In particular, this Program will investigate a full range of mechanisms that control ET-1 release and receptor specific actions in order to provide clinically relevant information.