Exercise Pressor Reflex in Peripheral Artery Disease: Roles of Flow Limitation and Reperfusion

项目概要/摘要 我们的目标是确定外周动脉疾病（PAD）心血管功能障碍的机制 然后研究能减少这些病理生理过程影响的治疗方法。我们有 表明PAD患者腿部运动时的运动加压反射（EPR）被夸大。的 PAD患者中扩大EPR的机制尚未彻底研究。利用人类 和动物实验，我们建议检查血流限制（BFR）和缺血再灌注的作用， (IR)强调诱发扩大的EPR。我们预计，阻断酸敏感离子通道（ASIC） 联合阿米洛利治疗可降低PAD患者的过度EPR，提高步行耐力。目标1： 确定BFR在诱导PAD中的过度EPR中的作用。我们假设BFR会导致 更高的H+/更低的pH值在运动肌肉的韧带，从而加重EPR通过刺激 ASIC。我们建议采用健康受试者的BFR来模拟PAD的BFR。我们推测BFR将 在安慰剂试验中，阿米洛利会增加EPR，在安慰剂试验中，阿米洛利会减少EPR，增加运动时间/负荷。 BFR条件。我们还推测阿米洛利将在PAD患者中发挥同样的有益作用。在动物 研究，我们推测股动脉闭塞的BFR将增加间质H+/降低pH，从而 通过ASIC亚型3（ASIC 3）和长时间闭塞来扩大EPR将上调ASIC 3表达 PAD的肌传入神经。目的2：探讨IR在PAD中诱发EPR增高的作用。 我们假设IR导致PAD中EPR升高，而阿米洛利降低了EPR升高 通过阻断ASIC由IR应激诱导。健康受试者将在自由流动下进行跖屈运动 缺血20 min后再灌注20 min。我们推测IR应力会加重 EPR。PAD患者在腿部血运重建前后还将进行跖屈运动。我们 推测阿米洛利将改善IR应激后受试者的EPR并增加运动时间/负荷， 血管重建的PAD患者。在动物实验中，我们将检测IR大鼠在不同时间的EPR 并推测IR大鼠再灌注满意可减轻EPR和升压反应 由传入神经的ASIC 3的激活诱导。目的3：确定ASIC对运动能力的影响， PAD和基本机制。我们推测，阿米洛利将减少升压反应， 增加PAD患者的跛行发作时间和步行距离/时间。在动物研究中， 我们推测IR诱导的过度EPR将在ASIC 3敲除大鼠中减弱。我们将 比较IR大鼠肌肉传入神经元中ASIC 3的蛋白水平及其电流反应， 不同的时间进程和它们的对应物作为对照。我们推测ASIC 3的表达及其与细胞凋亡的关系。 在IR起始阶段，肌肉传入神经元的电流反应将被放大， 将通过ASIC 3敲除或用足够的再灌注时间来降低。

PROJECT SUMMARY/ABSTRACT Our goal is to identify the mechanisms responsible for cardiovascular disability in peripheral artery disease (PAD) and to then examine therapies that will reduce the impact of these pathophysiologic processes. We have demonstrated that the exercise pressor reflex (EPR) during leg exercise is exaggerated in PAD patients. The mechanisms for the exaggerated EPR in PAD patients have not been examined thoroughly. Utilizing both human and animal studies, we propose to examine the roles of blood flow restriction (BFR) and ischemia-reperfusion (IR) stress in inducing the exaggerated EPR. We anticipate that a blockade of acid sensing ion channels (ASICs) with amiloride will reduce the exaggerated EPR and enhance the walking tolerance in PAD patients. Aim 1: Determine the role of BFR in inducing the exaggerated EPR in PAD. We hypothesize that BFR leads to a greater H+/lower pH in the interstitium of exercising muscles and thereby accentuates the EPR via stimulating ASICs. We propose to employ BFR in healthy subjects to simulate the BFR in PAD. We speculate that BFR will augment the EPR in the placebo trial and amiloride will reduce the EPR and increase exercise time/load under BFR condition. We also speculate that amiloride will play the same beneficial role in PAD patients. In animal studies, we speculate that BFR by femoral artery occlusion will increase interstitial H+/decrease pH thereby exaggerating the EPR via ASIC subtype 3 (ASIC3) and prolonged occlusion will upregulate ASIC3 expression in muscle afferent nerves of PAD. Aim 2: Determine the role of IR in inducing the exaggerated EPR in PAD. We hypothesize that IR contributes to the exaggerated EPR in PAD and amiloride reduces the exaggerated EPR induced by IR stress via blocking ASICs. Healthy subjects will perform plantar flexion exercise under free flow conditions and after 20 min ischemia followed by 20 min reperfusion. We speculate that IR stress will accentuate the EPR. PAD patients before and after leg revascularization will also perform plantar flexion exercise. We speculate that amiloride will improve the EPR and increase exercise time/load in subjects after IR stress and in PAD patients with revascularization. In animal studies, we will examine the EPR in IR rats at different time courses and speculate that in IR rats satisfied reperfusion will alleviate the EPR and the pressor response induced by activation of afferent nerves’ ASIC3. Aim 3: Determine the effects of ASIC on exercise ability in PAD and fundamental mechanisms. We speculate that amiloride will decrease the pressor response to walking and increase the claudication onset time and walking distance/time in PAD patients. In animal studies, we speculate that exaggerated EPR induced by the IR will be attenuated in ASIC3 knockout rats. We will compare the protein levels of ASIC3 and its current response in muscle afferent neurons between IR rats at different time courses and their counterparts serving as controls. We speculate that ASIC3 expression and its current response in muscle afferent neurons will be amplified during the initiating IR stage and the effects of IR will be reduced by ASIC3 knockout or with sufficient time of reperfusion.