Vasomotor Control of Descending Vasa Recta

描述（由申请人提供）：肾髓质的微循环捕获通过Henle袢和集管沉积到间质中的NaCI和尿素，并将血流分配到肾的缺氧区域。大量证据表明，髓质灌注与肾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15微米的小动脉微血管，血液通过它到达髓质。DVR被平滑肌/周细胞包围，平滑肌/周细胞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ca2 +信号和通道结构的方法。使用这些方法，我们已经证明周细胞通过激活ca2 +依赖的CI-电导和抑制K+通道来去极化。这些事件伴随着血管紧张素II诱导的血管收缩。为了促进我们对DVR周细胞生理学的理解，我们提出以下目标：目的1)我们将研究ca2 +依赖性CI-电导调节周细胞膜电位的生理特性。我们将确定阴离子的选择性和对全细胞电流抑制剂的敏感性，以及我们之前确定的11ps CICa通道。我们将测试蛋白激酶C和蛋白激酶A在大鼠周细胞CICa通道激活和失活中的作用。目的2)我们将检查血管紧张素II （Angll）对周细胞Kv通道的抑制。我们将测试Angll抑制整个细胞电流的阳离子选择性。我们将确定Angll在细胞附着斑块中抑制的58ps Kv通道的阳离子选择性和激活机制。目的3)我们将测试20-HETE介导Angll诱导的DVR血管收缩和Kv通道抑制的作用。我们将测试20-HETE在调节周细胞膜电位和抑制K+通道中的作用。目的4)我们将确定哪些途径参与ca2 +进入DVR周细胞。我们将研究ca2 +存储耗尽打开的ca2 +进入途径的电流电压特性和阳离子选择性。我们将验证电压操作ca2 +进入参与周细胞信号传导的假设。我们将确定VOCC和非选择性阳离子通道在Angll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.