Integrated Tubular and Vascular Structure and Function in Renal Inner Medulla

描述（由申请人提供）：内髓尿浓缩机制是一种重要但了解甚少的肾功能。本项目的目标是促进我们对结构组织和功能之间关系的理解，包括无机离子，尿素和水的通量，以及哺乳动物肾髓质中的尿液浓缩机制。三维结构强调了内髓腔不是一个单一的混合良好的腔室。对Henle环跨上皮NaCl、尿素和水渗透性的不完全了解是创建解释IM渗透梯度和UCM生成的高级模型的唯一最关键障碍。只有考虑到肾IM的三维结构和功能架构，才能充分理解UCM。基于其他人的工作和我们以前在确定功能组织和溶质和水通量方面的工作，将研究以下三个具体目标。目的：1、测定中度浓缩大鼠Henle肌袢对水、尿素和NaCl的通透性。目的2，确定IM中Henle环和CD环、血管网络和间质结间隙（INS）的功能结构。目的3测定利尿和抗利尿大鼠Henle袢的尿素和NaCl渗透性，并观察加压素对Henle袢的影响。试验性办法将包括：1）使用生理功能的免疫细胞化学标记物从连续切片产生Henle袢、CD和直血管的所有IM细肢的三维重建，以鉴定小管和血管节段、细胞运输功能的位点和间质区室，并确定结构与结构的相互作用，和2）通过体外微灌注直接测量，的NaCl，尿素，和水的渗透性的特定薄肢段中定义的重建。将在体外使用和不使用加压素的情况下研究肾小管渗透性，并将在体内水利尿、抗利尿和暴露于加压素后研究渗透性。

DESCRIPTION (provided by applicant): The inner medullary urinary concentrating mechanism is an important yet poorly understood renal function. The goal of this project is to advance our understanding of the relationships between structural organization and function, including fluxes of inorganic ions, urea, and water, and the urine concentrating mechanism in the mammalian renal medulla. Three-dimensional architecture underscores the paradigm that the inner medullary interstitium is not one single well-mixed compartment. Incomplete knowledge of loop of Henle transepithelial NaCl, urea, and water permeabilities is the single most critical barrier to creating advanced models that explain generation of the IM osmotic gradient and the UCM. The UCM can only be fully understood by taking into consideration three-dimensional structural and functional architecture of the renal IM. Based on the work of others and on our previous work in determining the functional organization and solute and water fluxes, the three following specific aims will be investigated. Aim 1, determination of water, urea, and NaCl permeabilities of IM loops of Henle from moderately-concentrating rats. Aim 2, determination of functional architecture of loops of Henle and CDs, vascular networks, and interstitial nodal spaces (INSs) in the IM. Aim 3, determination of urea, and NaCl permeabilities of loops of Henle from diuretic and antidiuretic rats, and following vasopressin treatment in vivo and in vitro. Experimental approaches will include: 1) production of three-dimensional reconstruction of all IM thin limbs of Henle's loops, CDs, and vasa recta from serial sections, using immunocytochemical markers of physiological function to identify tubule and vessel segments, sites of cellular transport functions, and interstitial compartments and determination of structure-to-structure interactions, and 2) direct measurements, by in vitro microperfusions, of the NaCl, urea, and water permeabilities of specific thin limb segments defined in the reconstructions. Tubule permeabilities will be investigated with and without vasopressin in vitro, and permeabilities will be investigated following water diuresis, antidiuresis, and exposure to vasopressin in vivo.