Vasomotor Control of Descending Vasa Recta

描述（由申请方提供）：肾髓质的微循环通过Henle袢和集合管捕获沉积到肾小管的NaCl和尿素，并将血流分配到肾脏的缺氧区域。大量证据表明，髓质灌注与肾脏对盐和水排泄的调节以及急性肾衰竭的发生有关。直降血管（DVR）是直径为15 μ m的小动脉微血管，血流通过该微血管到达髓质。DVR被平滑肌/周细胞包围，赋予收缩特性以调节血管活性。我们现在已经建立了研究DVR周细胞的Ca 2+信号和通道结构的方法。利用这些方法，我们已经表明，周细胞通过激活Ca 2+依赖的Cl-电导和抑制K+通道来脱钙。这些事件伴随血管紧张素II诱导的血管收缩。为了加深对DVR周细胞生理学的理解，我们提出了以下目的：目的1）我们将研究调节周细胞膜电位的Ca 2+依赖性Cl-电导的生理特性。我们将确定阴离子的选择性和敏感性的抑制剂的全细胞电流和11 pS CICa通道，我们以前确定。我们将测试蛋白激酶C和蛋白激酶A在大鼠周细胞CICa通道的激活和失活中的作用。目的2）研究血管紧张素II（AngII）对外周细胞Kv通道的抑制作用。我们将测试AngII可抑制的全细胞电流的阳离子选择性。我们将确定AngII在细胞附着的贴片中抑制的58 pS Kv通道的阳离子选择性和激活机制。目的3）检测20-HETE在AngII诱导的DVR血管收缩和Kv通道抑制中的作用。我们将测试20-HETE调节周细胞膜电位和抑制K+通道的作用。目的4）明确DVR周细胞内Ca 2+内流的途径.我们将研究由Ca 2+库耗尽打开的Ca 2+进入途径的电流电压特性和阳离子选择性。我们将检验电压操纵的Ca 2+内流参与周细胞信号传导的假说.我们将确定VOCC和非选择性阳离子通道在AngII信号传导中的作用，并测试蛋白激酶C在其激活中的作用。

DESCRIPTION (provided by applicant): The microcirculation of the renal medulla traps NaCI and urea deposited to the interstitium by the loops of Henle and collecting ducts and distributes blood flow to a hypoxic region of the kidney. Substantial evidence has linked medullary perfusion to renal regulation of salt and water excretion and genesis of acute renal failure. Descending vasa recta (DVR) are 15 um diameter arteriolar microvessels through which blood flow reaches the medulla. DVR are surrounded by smooth muscle / pericytes that impart contractile properties to regulate vasoactivity. We have now established methods to study Ca 2+ signaling and channel architecture of the DVR pericyte. Using those methods we have shown that pericytes depolarize through activation of a Ca 2+-dependent CI- conductance and inhibition of K+ channels. These events accompany angiotensin II induced vasoconstriction. To advance our understanding of the physiology of the DVR pericyte, we propose the following aims: Aim 1) We will examine the physiological properties of the Ca 2+-dependent CI- conductance that regulates pericyte membrane potential. We will determine the anion selectivity and sensitivity to inhibitors of whole cell currents and the 11 pS CICa channel we previously identified. We will test the roles of protein kinase C and protein kinase A in the activation and inactivation of the rat pericyte CICa channel. Aim 2) We will examine pericyte Kv channel suppression by angiotensin II (Angll). We will test the cation selectivity of Angll suppressible whole cell currents. We will determine the cation selectivity and activation mechanisms of a 58 pS Kv channel that Angll suppresses in cell attached patches. Aim 3) We will test the role of 20-HETE to mediate Angll induced DVR vasoconstriction and Kv channel inhibition. We will test the role of 20-HETE to regulate pericyte membrane potential and suppress K+ channels. Aim 4) We will determine which pathways participate in Ca 2+ entry in DVR pericytes. We will examine the current voltage characteristics and cation selectivity of Ca 2+ entry pathways opened by Ca 2+store depletion. We will test the hypothesis that voltage operated Ca 2+ entry participates in pericyte signaling. We will determine the role of VOCC and nonselective cation channels in Angll signaling and test a role for protein kinase C in their activation.