EFFECT OF SYMP NEURAL BLOCKADE ON REACTIVE HYPEREMIA & RESPONSES IN OSA

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。 本研究的目的是更好地了解交感神经系统在阻塞性睡眠呼吸暂停(OSA)患者血管张力调节中的作用。本方案的具体目的是确定：1)最大血管扩张剂容量(反应性充血血流反应，RHBF)；2)交感血管收缩张力对RHBF的影响；3)交感血管收缩张力对低氧诱导的OSA血管扩张的影响。根据初步数据，我们推测阻塞性睡眠呼吸暂停患者的血管扩张机制受损。我们进一步假设，对血管扩张剂刺激的反应减弱是由于交感神经张力增强。这些目标将在三项采用类似技术的独立研究中得到解决。在研究I中，我们将测定阻塞性睡眠呼吸暂停综合征患者和对照组手臂和腿部的RHBF。在研究II中，我们将确定区域前臂交感神经阻滞(Bier阻滞剂，见下文)对阻塞性睡眠呼吸暂停综合征和对照组RHBF的影响。在第三项研究中，我们将确定Bier阻滞剂对阻塞性睡眠呼吸暂停低氧患者和对照组前臂血管扩张的影响。在给定的一天，每个受试者只会进行三项研究中的一项。然而，受试者可能会被邀请在另一天回来参加上述其他研究之一。为了确定OSA治疗是否能逆转血管功能障碍，OSA患者将在接受持续气道正压治疗(CPAP)治疗1-6个月后参加同一项研究。

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. The purpose of this study is to better understand the role the sympathetic nervous system plays in the regulation of vascular tone in patients with obstructive sleep apnea (OSA). The specific aims of this protocol are to determine: 1) the maximal vasodilator capacity (reactive hyperemic blood flow response, RHBF); 2) the effects of sympathetic vasoconstrictor tone on RHBF; and 3) the effect of sympathetic vasoconstrictor tone on hypoxia-induced vasodilation in OSA. Based on preliminary data, we postulate that in OSA mechanisms of vasodilation are impaired. We further postulate that the reduced response to vasodilator stimuli is due to enhanced sympathetic tone. These aims will be addressed in 3 separate studies that employ similar techniques. In Study I we will determine RHBF in the arm and leg in OSA and in controls. In Study II we will determine the effect of regional forearm sympathetic blockade (Bier block, see below) on RHBF in OSA and in controls. In Study III we will determine the effect of the Bier block on forearm vasodilation induced by systemic hypoxia in OSA and in controls. Only one of the 3 studies will be performed in each subject on a given day. However, the subject may be invited to return on another day to participate in one of the other studies described above. To determine whether OSA therapy reverses vascular dysfunction, OSA patients will participate in the same study after 1-6 months of OSA treatment with continuous positive airway pressure therapy (CPAP).