Renin regulation by nitric oxide

一氧化氮对肾素的调节

基本信息

批准号：
7010667
负责人：
WILLIAM H BEIERWALTES
金额：
$ 31.64万
依托单位：
HENRY FORD HEALTH SYSTEM
依托单位国家：
美国
项目类别：
财政年份：
2004
资助国家：
美国
起止时间：
2004-03-08 至 2008-02-29
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7010667
关键词：
cGMP dependent protein kinase cyclic AMP cyclic GMP enzyme activity gene expression genetically modified animals laboratory mouse laboratory rat nitric oxide phosphodiesterases prostaglandin E prostaglandin endoperoxide synthase renal glomerulus renal tubule renin renin angiotensin system tissue /cell culture

项目摘要

The renin-angiotensin system produces the potent vasoconstrictor angiotensin II, which is involved in i regulation of vascular resistance, blood pressure, and virtually every form of hypertension. Renin is the rate-i limilmg enzymatic step in angiotensin formation. In the kidney, the vasoconstriction by angiotensin is buffered by the vasodilator endothelium-derived nitric oxide (NO). We propose that NO both counteracts angiotensin-induced vasoconstriction and regulates its formation by differentially regulating renin secretion. NO has been reported to both inhibit and stimulate renin secretion, but it is unclear how these different effects could occur. While the cyclic nucleotide which stimulates renin secretion is cAMP, we hypothesize that cGMP, the second messenger of NO, inhibits renin release when cAMP levels are low by activating protein kinase GI! (PKGII) and increasing JG cell intracellular calcium. In contrast, when cAMP is increased by secretagogues such as prostaglandin (PG)E, cGMP stimulates renin release indirectly by inhibiting phosphodiesterase (PDE)-3 and exaggerating cAMPs effects by reducing its metabolism. In aim 1, we propose that with low cAMP levels, NO inhibits renin by stimulating cGMP production and increasing PKGII activity in the JG cells. We will study effects of NO and cGMP on renin without stimulating cAMP both in vitro (primary cultures of isolated JG cells and isolated glomeruli) and in vivo using eNOS knockout mice. In aim 2, we propose that if cAMP levels are elevated, NO enhances renin release by cGMP inhibition of PDE-3 and potentiation of cAMP-mediated renin stimulation. We will study cAMP and macula densa stimulation of renin, blocking PDEs that break down either cGMP or CAMP, using primary JG cultures, isolated glomeruli (without the macula densa) and renal cortical slices (with the macula densa). We will use nNOS knockout mice to see if NO from the macula densa mediates renin stimulation. In aim 3 we propose that prostanoids, particularly PGE2 produced by COX-2 in the macule dense, regulate cAMP levels in JG cells. Co-expression of COX-2 and nNOS in the macula densa suggests NO's effect on renin depends on COX-2 expression and activity. We will manipulate COX-2 expression and PG synthesis in the macula densa and study the effects of NO and cGMP, using renal cortical slices and in vivo experiments stimulating macula densa-mediated renin secretion in rats and nNOS knockout mice. These studies should reveal the dual pathways by which NO can either inhibit or stimulate renin secretion.

肾素-血管紧张素系统产生有效的血管收缩剂血管紧张素II，它参与血管阻力、血压和几乎所有形式的高血压的调节。肾素是血管紧张素形成中的限速酶促步骤。在肾脏中，血管紧张素引起的血管收缩被内皮衍生的一氧化氮 (NO) 缓冲。我们认为NO既可以抵消血管紧张素诱导的血管收缩，又可以通过差异性调节肾素分泌来调节其形成。据报道，NO 既能抑制又能刺激肾素分泌，但尚不清楚这些不同的作用是如何发生的。虽然刺激肾素分泌的环核苷酸是cAMP，但我们假设NO的第二信使cGMP在cAMP水平较低时通过激活蛋白激酶GI来抑制肾素释放！ (PKGII) 并增加 JG 细胞胞内钙。相反，当前列腺素 (PG)E 等促分泌剂增加 cAMP 时，cGMP 通过抑制磷酸二酯酶 (PDE)-3 并通过降低其代谢来增强 cAMP 的作用，从而间接刺激肾素释放。在目标 1 中，我们提出，在 cAMP 水平较低的情况下，NO 通过刺激 JG 细胞中的 cGMP 产生和增加 PKGII 活性来抑制肾素。我们将在体外（分离的 JG 细胞和分离的肾小球的原代培养物）和体内使用 eNOS 敲除小鼠研究 NO 和 cGMP 对肾素的影响，而不刺激 cAMP。在目标 2 中，我们提出，如果 cAMP 水平升高，NO 通过 cGMP 抑制 PDE-3 和增强 cAMP 介导的肾素刺激来增强肾素释放。我们将使用原代 JG 培养物、分离的肾小球（不含致密斑）和肾皮质切片（带有致密斑）来研究 cAMP 和致密斑对肾素的刺激，阻断分解 cGMP 或 CAMP 的 PDE。我们将使用 nNOS 敲除小鼠来观察来自致密斑的 NO 是否介导肾素刺激。在目标 3 中，我们提出前列腺素类化合物，特别是黄斑致密区中 COX-2 产生的 PGE2，调节 JG 细胞中的 cAMP 水平。 COX-2 和 nNOS 在致密斑中的共表达表明 NO 对肾素的影响取决于 COX-2 的表达和活性。我们将利用肾皮质切片和刺激大鼠和 nNOS 敲除小鼠中致密斑介导的肾素分泌的体内实验，操纵致密斑中的 COX-2 表达和 PG 合成，并研究 NO 和 cGMP 的影响。这些研究应该揭示NO可以抑制或刺激肾素分泌的双重途径。