Renin regulation by nitric oxide

一氧化氮对肾素的调节

• 批准号: 6867419
• 负责人: WILLIAM H BEIERWALTES
• 金额: $ 32.4万
• 依托单位: HENRY FORD HEALTH SYSTEM
• 依托单位国家: 美国
• 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/6867419
• 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

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血管紧张素II，该血管收缩蛋白II与I调节血管耐药性，血压以及几乎每种形式的高血压有关。 肾素是血管紧张素形成的limilmg酶促步骤。 在肾脏中，血管紧张素的血管收缩被血管舒张剂内皮衍生的一氧化氮（NO）缓冲。 我们建议，没有两种应对血管紧张素引起的血管收缩，并通过差异调节肾素分泌来调节其形成。 据报道，尚无抑制和刺激肾素分泌，但尚不清楚如何发生这些不同的影响。 虽然刺激肾素分泌的环状核苷酸是cAMP，但我们假设CGMP是NO的第二个信使，当CAMP水平通过激活蛋白激酶GI而降低cAMC的肾素释放！ （PKGII）并增加JG细胞内钙。 相反，当前列腺素（PG）E等促分子增加cAMP时，CGMP通过抑制磷酸二酯酶（PDE）-3并通过减少其代谢而间接刺激肾素释放。 在AIM 1中，我们提出，在较低的营地水平下，NO通过刺激CGMP的产生并增加JG细胞中的PKGII活性来抑制肾素。 我们将使用ENOS基因敲除小鼠研究NO和CGMP对肾素的影响（分离的JG细胞的一级培养和分离的肾小球）和体内的影响。 在AIM 2中，我们建议，如果cAMP水平升高，则不会通过CGMP抑制PDE-3和cAMP介导的肾素刺激增强肾素释放。 我们将使用原发性JG培养物，分离的肾小球（不含黄斑densa）和肾皮质切片（带有黄斑densa）来研究肾脏刺激肾素，阻断CGMP或CAMP的PDE，阻止CGMP或CAMP的PDE。 我们将使用NNOS基因敲除小鼠，看看Macula densa中的NO是否介导了肾素刺激。 在AIM 3中，我们建议前列腺素，特别是Cox-2在Macule致密中产生的PGE2，调节JG细胞中的cAMP水平。 黄斑densa中Cox-2和NNO的共表达表明NO对肾素的影响取决于Cox-2的表达和活性。 我们将使用肾皮质切片和刺激大鼠和NNOS敲除小鼠的黄斑densa介导的肾素分泌的肾皮质切片和体内实验来操纵Macula densa中的COX-2表达和PG合成，并研究NO和CGMP的效果。 这些研究应揭示双重途径不能抑制或刺激肾素分泌。