Analysis of distal conboluted tubule function in vivo

描述(由申请人提供)： 在美国，高血压影响着大约25%的成年人口，是中风、心肌梗死、充血性心力衰竭和慢性肾脏疾病死亡的重要危险因素。肾脏的远端曲管(DCT)在钠的重吸收(主要是通过氯化钠共转运体，NCC)从而调节血压方面起着关键作用。假性低醛固酮增多症II型(PHAII)最能说明这一点，该病以高钾性高血压为特征，由NCC调节器中增强其活性的基因缺陷引起。PHAII可以通过使用噻嗪类利尿剂治疗来治愈，这种利尿剂可以特异性地抑制NCC。重要的是，噻嗪类利尿剂是大多数高血压患者的首选治疗药物，而不仅仅是PHAII患者。对于PHAII是否仅仅是由NCC活动改变引起的，或者是否涉及其他离子通道和转运体的调节失调，存在争议。也有证据表明，NCC的活性受盐皮质激素醛固酮的调节。由于DCT中盐皮质激素受体的水平较低，因此，醛固酮对该肾段的生理作用尚不清楚。这项建议旨在描述两种小鼠模型的特征，以更好地了解PHAII和DCT的功能。(1)在DCT中高表达NCC的小鼠的建立和分析，作为PHAII的可能模型。血压测量、尿液和血浆电解质分析将与蛋白质组分析结合进行。这些参数将在正常饮食以及钠和钾水平已被改变的饮食中进行研究。将对硫化物使任何缺陷正常化的能力进行评估。(2)诱导的，DCT特异性的破坏盐皮质激素受体，以深入了解醛固酮在DCT功能中的作用。这些小鼠将被产生，类似于AIM(1)，将在不同的饮食条件下进行血压和电解质测量。在肾脏病学和负责任的研究行为方面的教学计划将补充研究计划，以帮助候选人实现其长期的职业目标，即在学术环境中进行独立的基础肾脏学研究。DCT生理学的领导者David Ellison博士将指导候选人的科学发展，高血压小鼠模型的领导者Donald Kohan博士也将提供意见。

DESCRIPTION (provided by applicant): Hypertension affects approximately 25% of the adult population in the United States and is an important risk factor for death from stroke, myocardial infarction, congestive heart failure, and chronic kidney disease. The distal convoluted tubule (DCT) of the kidney plays a critical role in the reabsorption of sodium (primarily via the sodium chloride cotransporter, NCC) and hence in regulation of blood pressure. This is best illustrated by the disease Pseudohypoaldosteronism type II (PHAII), characterized by hyperkalemic hypertension, caused by gene defects in regulators of NCC that enhance its activity. PHAII is remediable by treatment with thiazide diuretics, which specifically inhibit NCC. Importantly, thiazide diuretics are the first therapuetic choice in the majority of hypertensive patients, not just those with PHAII. There is controversy as to whether PHAII is caused solely by altered NCC activity, or whether dysregulation of other ion channels and transporters is involved. There is also evidence that NCC activity is regulated by the mineralocorticoid hormone aldosterone. Since levels of the mineralocorticoid receptor are low in the DCT, the physiological effects of aldosterone on this kidney segment are unclear. This proposal aims to characterize two mouse models to give better insight into PHAII and DCT function. (1) Generation and analysis of mice over-expressing NCC in the DCT, as a possible model of PHAII. Blood pressure measurements, and analysis of urinary and plasma electrolytes will be performed in conjunction with proteomic analysis. These parameters will be studied on a normal diet, and on diets in which sodium and potassium levels have been modified. The ability of thiazides to normalize any defects will be assessed. (2) Inducible, DCT-specific disruption of the mineralocorticoid receptor, to gain insight into the role of aldosterone in DCT function. These mice will be generated, and similarly to aim (1), blood pressure and electrolyte measurements will be performed under various dietary conditions. A didactic program in nephrology and in the responsible conduct of research will complement the research program to assist the candidate in achieving his long term career goal of performing independent basic nephrology research in an academic setting. Dr. David Ellison, a leader in DCT physiology will mentor the candidate's scientific development, as will input from Dr. Donald Kohan, a leader in mouse models of hypertension.