Increased Plasma Nitrite, Tissue Oxygenation and Functional Changes in PAD

描述(申请人提供)：外周动脉疾病(PAD)是由腿部动脉粥样硬化性闭塞引起的。它影响着5%的美国人口，超过50岁，其中三分之一患有间歇性跛行(IC)，定义为行走时发生的缺血性腿部疼痛，并随着休息而改善。可以(A)显著改善缺血区的氧合和(B)慢性增加这些缺血区的血管生长的干预措施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，也是内皮细胞产生NO的标志。最近，一些研究已经证明了包括亚硝酸盐在内的没有类似物的内分泌作用。这些等价物可以在血液中被输送到外周组织床，在那里在低氧条件下，它们可以转化为NO，增加血流量和氧气输送。这可能与动脉闭塞症(PAD)有关，特别是在运动时，组织缺血是限制因素。这项建议的假设是，在患有PAD和IC的患者中，定期服用高硝酸盐补充剂可提高血浆亚硝酸盐水平，并结合8周肢体缺血阈值(SET)的监督运动训练，将产生比安慰剂加肢体缺血阈值(PET)监督运动更大的临床益处(COT和PWT增加)。为了充分开发，动力和执行一项更大的研究，以下具体目标将探索我们的假设使用24人(每组12人)与PAD和IC：具体目标1a：确定部分PAD患者可以达到所需水平的血浆亚硝酸盐(&gt；500 Nm在饮酒后180分钟后)在一个8周的研究耐受量。具体目标1b：在这些受试者中，在随机到SET或PET的8周之间，在分级运动试验中确定COT、PWT和VO2峰值的差异。特定目的2：确定(A)组织氧合(近红外光谱)和(B)NO衍生物种(血浆和红细胞亚硝酸盐、硝酸盐、亚硫醇)、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后的差异3：确定SET或PET后腓肠肌(通过活检)(通过活检)(A)血管生成和动脉生成(与周围周细胞的毛细血管密度、增殖细胞核抗原和细胞凋亡)和氧化能力(纤维类型组成、柠檬酸合成酶活性)和(B)内皮功能(臂动脉FMD)的差异。 公共卫生相关性：外周动脉疾病(PAD)是一种由腿部动脉粥样硬化性闭塞引起的心血管疾病(CVD)。它影响了大约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)，定义为行走时发生的缺血性腿部疼痛，并随着休息而改善。我们建议，通过饮料补充血浆亚硝酸盐，我们可以(A)显著改善缺血区的氧合，(B)慢性增加缺血区的血管生长，允许更大的急性运动耐量，减轻运动顺应性的负担，并促进功能和生活质量的更大改善

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. PUBLIC HEALTH RELEVANCE: Peripheral artery disease (PAD) is a form of cardiovascular disease (CVD) caused by atherosclerotic occlusions in the legs. It affects approximately 5% of the US population over 50 yrs of age, one third of which suffer from intermittent claudication (IC), defined as ischemic leg pain that occurs with walking and improves with rest. We propose by supplementing plasma nitrite via a beverage we can (A) acutely improve oxygenation to areas of ischemia and (B) chronically increase vessel growth to these ischemic areas, would allow for greater acute exercise tolerance, ease the burden of exercise compliance and facilitate greater improvements in function and quality of life