MICROVASCULAR CONTROL OF JUXTAMEDULLARY NEPHRON FUNCTION

这个项目的目的是勾勒出 参与调节延髓旁肾的血流 老鼠肾。重点放在了对 血管系统维持血流和肾小球的能力 面对血流灌注变化时的滤过率常数 压力，包括评价几种机制的作用 这可能与这种自我调节反应有关。(主要 候选的包括小管小球反馈和肌源性 机制。)此外，肾微血管对 将对重要的血管活性物质进行评估。 实验将使用体外制剂进行，该制剂 涉及延髓旁同种异体血的灌流 来自大鼠肾脏的肾脏。此实验设置允许 肾动脉和小动脉单位的可视化。 将利用视频测量技术来评估血液流动 和节段性血管直径对血管内径变化的反应 灌流压力或肾小管液体流向远端的改变 肾单位；微穿刺术将用于测量 血管系统中的静水压力，收集管状液，以及 从近端肾小管部位灌流肾小管。实验将是 用来表征体外的自我调节反应，以 确定肾血管系统的生肌能力，以及 测定肾小管球部反馈的敏感性 系统在这些条件下。这些实验将提供 旨在评估相关研究的基础 肌源性和小管小球反馈的作用 自我调节反应的机制。此外，研究还包括 将执行以建立自动调节的依赖关系 关于小球小球的几个可能的调节器 反馈系统，并调查建议的影响 肾小管小球反馈环上的自动调节介质。 这些研究将有助于描绘出 自动调节、小管小球反馈、肌源性和 体液对肾脏微血管功能的影响。

The purpose of this project is to delineate the mechanisms involved in regulating blood flow to juxtamedullary nephrons of the rat kidney. Emphasis is placed on characterization of the ability of the vasculature to maintain blood flow and glomerular filtration rate constant in the face of alterations in perfusion pressure, including evaluation of the role of several mechanisms which may be involved in this autoregulatory response. (Primary candidates include the tubuloglomerular feedback and myogenic mechanisms.) Also, the renal microvascular responses to important vasoactive agents will be evaluated. Experiments will be performed using an in vitro preparation which involves perfusion with homologous blood of juxtamedullary nephrons from the rat kidney. This experimental setting allows visualization of the renal arterial and arteriolar units. Videometric techniques will be utilized to evaluate the blood flow and segmental vascular diameter responses to changes in perfusion pressure or alterations in tubular fluid flow to the distal nephron; micropuncture techniques will be used to measure hydrostatic pressure in the vasculature, collect tubular fluid, and perfuse tubules from proximal tubular sites. Experiments will be performed to characterize the autoregulatory response in vitro, to determine the myogenic capability of the renal vasculature, and to determine the sensitivity of the tubuloglomerular feedback system under these conditions. These experiments will provide the basis for studies designed to evaluate the relative contributions of myogenic and tubuloglomerular feedback mechanisms to the autoregulatory response. In addition, studies will be performed to establish the dependency of autoregulation upon a number of putative modulators of the tubuloglomerular feedback system, and to investigate the influence of suggested autoregulatory mediators on the tubuloglomerular feedback loop. These studies will help delineate the interrelationships between autoregulatory, tubuloglomerular feedback, myogenic, and humoral influences on renal microvascular function.