VESTIBULOSYMPATHETIC REFLEXES IN HUMANS

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。本研究的具体目标是进一步了解前庭系统的激活如何通过调节交感神经活动和外周血管阻力参与直立。我们将研究肌肉交感神经活动（MSNA）和血压反应：1）在耳石器官的动态接合期间，2）在直立姿势下耳石器官的接合期间，3）在易患直立不耐受的受试者中前庭交感神经反射的接合期间。试点数据表明，动态刺激的耳石器官eleaned更大的MSNA增加动态，而不是静态的耳石器官的参与。这一发现将支持这一假设，前庭交感神经反射，介导的动态刺激的耳石器官，有助于直立耐力与姿势的变化。初步数据还表明，通过头向下旋转（HDR）的前庭交感神经反射增加MSNA与身体姿势无关。这一发现将提供第一个证据表明，前庭激活在直立姿势有助于交感神经流出，并将支持前庭系统有助于直立在人类的概念。最后，试验数据表明，MSNA的前庭激活在与直立不耐受相关的条件下减弱（即，特发性直立性低血压、前庭缺陷受试者和高度训练的耐力运动员），并且在这些受试者中，血压在前庭激活期间降低。

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 specific goals of this study are to further our understanding of how activation of the vestibular system participates in orthostasis by its regulation of sympathetic nerve activity and peripheral vascular resistance in humans. We will investigate muscle sympathetic nerve activity (MSNA) and blood pressure responses: 1) during dynamic engagement of the otolith organs, 2) during engagement of the otolith organs in the upright posture, and 3) during engagement of the vestibulosympathetic reflex in subjects predisposed to orthostatic intolerance. Pilot data suggests that dynamic stimulation of the otolith organs elicits greater increases in MSNA during dynamic rather than static engagement of the otolith organs. This finding would support the hypothesis that the vestibulosympathetic reflex, mediated by dynamic stimulation of the otolith organs, contributes to orthostatic tolerance with changes in posture. Preliminary data also suggests that increases in MSNA by the vestibulosympathetic reflex via head-down rotation (HDR) is independent of body posture. This finding would provide the first evidence that vestibular activation in the upright posture contributes to sympathetic outflow and will support the concept that the vestibular system contributes to orthostasis in humans. Finally, pilot data suggests that vestibular activation of MSNA is attenuated in conditions that are associated with orthostatic intolerance (i.e., idiopathic orthostatic hypotension, vestibular deficient subjects, and highly trained endurance athletes), and that, blood pressure is reduced during vestibular activation in these subjects.