Increased Plasma Nitrite, Tissue Oxygenation and Functional Changes in PAD

描述（由申请人提供）：外周动脉疾病（PAD）由腿部动脉粥样硬化闭塞引起。它影响5%的50岁以上的美国人口，其中三分之一患有间歇性跛行（IC），定义为步行时发生的缺血性腿部疼痛，休息后改善。可以（A）急性改善缺血区域的氧合和（B）慢性增加这些缺血区域的血管生长的干预将允许更大的运动耐受性和顺应性，并促进功能和生活质量的更大改善。血浆亚硝酸盐曾被认为是一种生物惰性副产物和内皮NO产生的标志物。最近，一些研究已经证明了NO当量的内分泌作用，包括亚硝酸盐。这些等价物可以在血液中运输到外周组织床，在缺氧条件下，它们可以转化为NO并增加血流和O2输送。这可能与动脉闭塞性疾病（PAD）有关，特别是在组织缺血是限制因素的运动期间。该建议的假设是，在PAD和IC受试者中，定期摄入高硝酸盐补充剂（可提高血浆亚硝酸盐），结合肢体缺血阈值（SET）下8周的监督运动训练，将产生比安慰剂加肢体缺血阈值（PET）下监督运动更大的临床获益（COT和PWT增加）。为了充分开发、加强和执行更大规模的研究，以下具体目标将使用24名患有PAD和IC的个体（每组12名）来探索我们的假设：具体目标1a：确定PAD患者的部分，其可以在8周的研究中以可耐受的体积达到期望的血浆亚硝酸盐水平（在饮料消耗后180分钟> 500 nM）。具体目标1b：在这些受试者中，确定随机分组至8周SET或PET期间分级运动试验期间COT、PWT和VO 2峰值的差异。具体目标二：确定（a）组织氧合（通过NIRS）和（B）NO衍生物质的差异（血浆和RBC亚硝酸盐、硝酸盐、亚硝基硫醇）、cGMP、氧化和亚硝化应激（血浆硝基酪氨酸和F2-异前列腺素）在SET或PET特定目标3后的跑步机测试期间：为了确定胃网膜肌（a）血管生成和动脉生成（毛细血管密度与周围周细胞、增殖细胞核抗原和凋亡）和氧化能力（纤维类型组成，柠檬酸合酶活性），和（B）SET或PET后的内皮功能（肱动脉FMD）。

DESCRIPTION (provided by applicant): Peripheral artery disease (PAD) is caused by atherosclerotic occlusions in the legs. It affects 5% of the US population over 50 yrs, one third of which suffer from intermittent claudication (IC), defined as ischemic leg pain that occurs with walking and improves with rest. An intervention that could (A) acutely improve oxygenation to areas of ischemia and (B) chronically increase vessel growth to these ischemic areas would allow for greater exercise tolerance and compliance and facilitate greater improvements in function and quality of life. Plasma nitrite was once considered a biologically inert byproduct and marker of endothelial NO production. Recently, several studies have demonstrated an endocrine role for NO equivalents, including nitrite. These equivalents may be transported in the blood to peripheral tissue beds, where under hypoxic conditions they can be converted to NO and increase blood flow and O2 delivery. This may be pertinent in an arterial occlusive disease (PAD), especially during exercise when tissue ischemia is the limiting factor. The hypothesis of this proposal is that in subjects with PAD and IC, regular consumption of a high nitrate supplement which raises plasma nitrite, in conjunction with 8 weeks of supervised exercise training at the limb ischemic threshold (SET) will produce a greater clinical benefit (increases in COT and PWT) than placebo plus supervised exercise at the limb ischemic threshold (PET). In order to adequately develop, power and execute a larger study, the following specific aims will explore our hypothesis using 24 individuals (12 per group) with PAD and IC: Specific Aim 1a: To determine the segment of PAD patients that can achieve the desired level of plasma nitrite (>500nM at 180min post beverage consumption) at a tolerable volume for an 8 week study. Specific Aim 1b: In these subjects, determine differences in COT, PWT and VO2peak during a graded exercise test, between randomization to 8 weeks of SET or PET. Specific Aim 2: To determine differences in (a) tissue oxygenation (by NIRS) and (b) NO-derived species (plasma and RBC nitrite, nitrate, nitrosothiol), cGMP, oxidative and nitrosative stress (plasma nitrotyrosine and F2-isoprostane) during treadmill testing following SET or PET Specific Aim 3: To determine differences in gastrocenemius muscle (via biopsy) (a) angiogenesis and arteriogenesis (capillary density with surrounding pericytes, proliferating cell nuclear antigen, and apoptosis) and oxidative capacity (fiber type composition, citrate synthase activity), and (b) endothelial function (brachial artery FMD) after SET or PET.