Renal Control of Blood Pressure in Early Diabetes

描述(由申请人提供)：我们已经证明，如果糖尿病患者首次出现高血糖，如果它发生在慢性一氧化氮(NO)合成抑制的条件下，会导致显着的肾血管收缩和高血压。这些高血糖的有害后果可以通过使用超氧化物歧化酶(SO)模拟物Tempoll进行抗氧化治疗来预防。潜在的假设是，早期糖尿病的高血糖导致血管紧张素II依赖的、超氧化物介导的肾压-钠尿关系的右移，而一氧化氮是预防高血压的重要中和力量。该项目中的实验将通过测试中心假设来确定这些重要相互作用的机制，该中心假设一氧化氮抵消依赖血管紧张素II的超氧化物介导的肾血管收缩，以预防糖尿病早期高血糖期间的高血压。实验将通过测试以下三个假设来验证这一点：1.一氧化氮是预防糖尿病发作时肾脏血管收缩和高血压所必需的。我们的L-NAME、ACh和肾小球滤过率数据支持这一点，但为了更好地揭示NO并确定其在早期糖尿病中控制肾功能的部位(S)，我们将： A.每天24小时测量肾血流量以量化阻力和滤过分数的变化；B.测定eNOS和nNOS的时间依赖性、葡萄糖依赖性和胰岛素依赖性的变化； C.确定血管扩张性前列腺素何时以及是否发挥NO的血管保护作用； D.利用基因敲除小鼠和注入拮抗剂来确定eNOS和nNOS的作用。 2.血管紧张素II增加了对高血糖时肾血管收缩和高血压的敏感性，并且是这些反应发生所必需的。我们的证据支持这一角色，但为了确定安吉尔的重要性，独立于L的名字导致的增长，我们将确定： A.低钠摄入是否会加剧糖尿病大鼠对一氧化氮合酶抑制的敏感性； B.通过减少肾脏质量来控制GFR来控制GFR与血压之间的联系； C.糖尿病的发病是否会导致Ang11高血压大鼠的高血压； D.血管紧张素转换酶对MAP和肾阻力的影响中的超氧阴离子非依赖性成分。 3.在高血糖开始时，超氧阴离子可引起肾脏血管收缩和高血压影响。我们已经证明，坦普尔可以预防L治疗的糖尿病大鼠的高血压，但为了更具体地说，在阻断或不阻断一氧化氮合酶的情况下，我们将确定： A.抗氧化剂治疗是否可以在不减少肾素分泌的情况下预防高血压；b.敲除SOD1是否会加剧高血压反应； C.转基因小鼠中增加的SOD1是否与temol相似，可以预防高血压； D.NADPH氧化酶的作用，通过测量p22Phox的表达和载脂蛋白的作用。

DESCRIPTION (provided by applicant): We have shown that the first onset of hyperglycemia in diabetes causes significant renal vasoconstriction and hypertension if it occurs under conditions of chronic nitric oxide (NO) synthesis inhibition. Those deleterious consequences of hyperglycemia are prevented by antioxidant treatment with the superoxide (SO) dismutase mimetic, tempol. The underlying hypothesis is that onset of hyperglycemia in early diabetes induces an angiotensin II-dependent, superoxide-mediated right-shift in the renal pressure-natriuresis relationship, and that nitric oxide is an important counteracting force that prevents hypertension. The experiments in this project will determine the mechanisms for these important interactions by testing the central hypothesis that nitric oxide counteracts angiotensin II-dependent, superoxide-mediated renal vasoconstriction to prevent hypertension during hyperglycemia early in diabetes. Experiments will test this by testing the 3 subhypotheses that: 1. Nitric oxide is required to prevent renal vasoconstriction and hypertension at the onset of diabetes. Our L-NAME, ACh, and glomerular filtration rate (GFR) data support this, but to better implicate NO and define the site(s) for its control of renal function in early diabetes, we will: a. measure renal blood flow 24 hr/d to quantify the changes in resistance and filtration fraction; b. determine the time-, glucose-, and insulin-dependent changes in eNOS and nNOS; c. determine when, and if, vasodilatory prostaglandins assume the vasoprotective role of NO; d. determine the roles of eNOS vs. nNOS using knockout mice and infusion of antagonists. 2. Angiotensin II increases sensitivity to renal vasoconstriction and hypertension during hyperglycemia and is required for those responses to occur. Our evidence supports this role, but to determine Angll's importance independent of L-NAME-induced increases we will determine: a. whether low-sodium intake exacerbates the sensitivity of diabetic rats to NOS inhibition; b. the link between GFR and blood pressure by using decreased kidney mass to control GFR; c. whether onset of diabetes causes hypertension in rats with Angll hypertension; d. the superoxide-independent component of Angll's influence on MAP and renal resistance. 3. Superoxide induces a renal vasoconstrictor and hypertensive influence at the onset of hyperglycemia. We have shown that tempol prevents hypertension in L-NAME-treated diabetic rats, but to more specifically implicate SO, with or w/o NOS blockade, we will determine: a. whether antioxidant treatment can prevent hypertension without decreasing renin secretion; b. whether knockout of SO dismutase-1 (SOD1) exacerbates the hypertensive response; c. whether increased SOD1 in transgenic mice protects against hypertension similar to tempol; d. the role of NADPH oxidase, by measuring p22 phox expression and the effect of apocynin.