FOREARM EXERCISE ON FLOW MEDIATED VASODILATION BEFORE HEMODIALYSIS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 良好的血管通路是血液透析的必要条件。血液透析的最佳途径是通过动脉和静脉直接吻合形成的自然动静脉瘘，最好是在非优势臂的前臂。然而，在美国，只有少数接受血液透析的患者有本土瘘。其主要原因是先天性瘘管，尤其是前臂的瘘管往往不能成熟为可用的瘘管。这在女性和老年患者中尤其如此，特别是那些患有血管疾病的患者。从病理生理学角度来看，这一失败的最可能原因是小血管不能充分扩张以适应必要的流速以用于透析和防止瘘管的凝结。最近的一项研究证实了这一假说，表明瘘管的结局与动脉和静脉的大小以及肱动脉对血流速度增加的扩张能力独立相关。后一种现象被称为流动介导的膨胀。血流介导性扩张(FMD)是一种测量大型导管动脉在血流速度增加时的扩张能力的指标。血流速度的增加会增加内皮细胞的剪切力，从而释放一氧化氮，产生血管扩张。因此，FMD是内皮功能的一种衡量标准，这已被证明在患有血管疾病的人中是受损的。如果在手术制造瘘管之前改善手臂血管的FMD，可能会导致更好的瘘管成熟。在其他研究中，锻炼已经被证明可以改善FMD，但从来没有人检验过前臂锻炼是否可以改善这一人群的FMD。这导致了目前的假设，即术前前臂锻炼将增加ESRD患者动静脉瘘患者的内皮依赖性FMD。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. A well functioning vascular access is a requisite for hemodialysis. The optimal access for hemodialysis is a native arteriovenous fistula created by direct anastomosis of an artery and vein preferably in the forearm of the non-dominant arm. However, only a minority of patients on hemodialysis in the United States have a native fistula. The major reason for this is that native fistulas, particularly in the forearm often fail to mature into a usable fistula. This is particularly true in women and older patients, especially those with vascular disease. Pathophysiologically, the most likely reason for this failure is small vessels that do not dilate sufficiently to accommodate the necessary flow rate to be usable for dialysis and to prevent clotting of the fistula. A recent study has confirmed this hypothesis by showing that fistula outcome is independently associated with artery and vein size and with the ability of the brachial artery to dilate in response to increased flow velocity. The latter phenomenon is known as flow mediated dilation. Flow mediated dilation (FMD) is a measure of the ability of a large conduit artery to dilate in response to an increased velocity of flow through the artery. The increased flow velocity creates an increase in shear stress on the endothelium that releases nitric oxide and produces vasodilation. Thus FMD is a measure of endothelial function and this has been shown to be impaired in people with vascular disease. If FMD of the vessels in the arm could be improved prior to surgical creation of a fistula it might lead to better fistula maturation. Exercise has been shown to improve FMD in other studies but it has never been examined whether forearm exercise can improve FMD in this population. This leads to the present hypothesis that preoperative forearm exercise will increase endothelial-dependent FMD in subjects with ESRD scheduled for an arteriovenous fistula.