Dietary Nitrate to Augment Exercise Training Benefits in DM+PAD

描述（由申请人提供）：外周动脉疾病（PAD）影响了美国50岁以上人口的5%，其中三分之一患有间歇性跛行（IC）。糖尿病患者（DM+PAD）中PAD的发病率大大增加，因此建议对无症状糖尿病患者进行PAD筛查。DM+PAD患者疾病进展为严重腿部缺血、下肢截肢和心血管事件的风险增加。血管内一氧化氮的减少可能是糖尿病的一个特别相关的问题，因为内皮源性一氧化氮的产生已被证明会因高血糖而减少，并且一氧化氮会被晚期糖基化终产物和活性氧灭活。我们之前的研究表明，只有PAD，而不是2型糖尿病(T2D)+PAD，受试者能够在运动训练后上调血管NO的生物利用度和相关的血浆亚硝酸盐信号，这些变化介导了更明显的功能反应。我们还发现，与安慰剂相比，单剂量摄入含有高硝酸盐的饮料会增加血浆亚硝酸盐，仅pad患者的COT和PWT分别增加18%和17%。此外，在长期治疗之后；A)在小鼠后肢缺血模型中，只有缺血肢体的血管生成和动脉生成明显增加；B)在健康人群中，经过两天的治疗，线粒体氧气效率提高，导致运动时氧气消耗减少。该建议的假设是，在T2D+PAD合并IC的患者中，定期摄入高硝酸盐补充剂（提高血浆亚硝酸盐），并在肢体缺血阈值（SET）进行12周的监督运动训练，将产生更大的临床益处(增加

DESCRIPTION (provided by applicant): Peripheral artery disease (PAD) affects 5% of the US population over 50 yrs, one third of which suffer from intermittent claudication (IC). The incidence of PAD in subjects with diabetes (DM+PAD) is so greatly increased that screening for PAD in asymptomatic diabetic subjects is recommended. DM+PAD patients are at increased risk for disease progression to critical leg ischemia, lower extremity amputation, and cardiovascular events. Reduced bioavailable vascular NO may be a particularly pertinent issue in diabetes given that endothelial derived NO production has been shown to be decreased by hyperglycemia, and NO is inactivated by advanced glycation end products and reactive oxygen species. We have previously shown PAD-only, but not type 2 diabetic (T2D)+PAD, subjects are able to up-regulate vascular NO bioavailability and related plasma nitrite signaling following exercise training and that these changes mediate a more pronounced functional response. We have also shown an 18% and 17% increase in COT and PWT respectively in PAD-only, following a single dose ingestion of a high-nitrate containing beverage which raises plasma nitrite in comparison to placebo. Additionally, following chronic treatment; A) In a murine model hind limb ischemia of angiogenesis and arteriogenesis were significantly increased only in the ischemic limb; and B) following two days treatment in healthy humans mitochondrial oxygen efficiency was increased causing a reduction in oxygen cost during exercise. The hypothesis of this proposal is that in T2D+PAD subjects with IC, regular consumption of a high nitrate supplement which raises plasma nitrite, in conjunction with 12 weeks of supervised exercise training at the limb ischemic threshold (SET) will produce a greater clinical benefit (increases in COT and PWT) relative to a group with the same exercise training but supplemented with placebo (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 T2D+PAD and IC: Specific Aim 1: To determine group differences in the change in COT, PWT and VO2peak during a maximal graded exercise test, following 12 weeks of supervised exercise training. Specific Aim 2: To determine group differences in the change in (a) tissue oxygenation (by NIRS) and (b) NO-derived species (plasma and RBC nitrite, nitrate, nitrosothiols, plasma nitrotyrosine), cGMP during a maximal graded exercise test, and (c) vascular function at rest (endothelial function), calf blood flow (plethysmography). Specific Aim 3a: To determine group differences in the change in gastrocnemius muscle for (a) angiogenesis (capillaries per unit area and per muscle fiber, endothelial cells with surrounding pericytes, relative fraction of type I, versus type II fibers). If differences exist we will look for changes in cell proliferation (PCNA) nd apoptosis (TUNEL); (b) oxidative capacity (citrate synthase activity); (c) mitochondrial volume and density; (d) mitochondrial oxygen efficiency (respiratory control ratio, the ratio of ATP phosphorylation rate per oxygen consumption rate (P/O ratio), and maximal rate of ATP production).