VESTIBULOSYMPATHETIC REFLEXES IN HUMANS

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。 这项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人类的交感神经活动和外周血管阻力来参与矫形。我们将研究肌肉交感神经活动(MSNA)和血压反应：1)在动态接触耳石器官时，2)在直立姿势下接触耳石器官时，3)在易发生立位耐受不良的受试者中，在参与前庭交感神经反射时。飞行员数据表明，在耳石器官的动态接触过程中，动态刺激耳石器官会引起MSNA的更大增加，而不是静态刺激。这一发现支持这样一种假设，即通过动态刺激耳石器官，前庭交感神经反射有助于随着姿势的改变而产生立位耐受。初步数据还表明，通过头向下旋转(HDR)的前庭交感神经反射(HDR)增加的MSNA与身体姿势无关。这一发现将提供第一个证据，证明直立状态下前庭的激活有助于交感神经流出，并将支持前庭系统有助于人类直立的概念。最后，飞行员数据表明，在与立位耐受性相关的情况下(即特发性直立性低血压、前庭缺陷患者和训练有素的耐力运动员)，MSNA的前庭激活会减弱，并且这些受试者在前庭激活期间血压会降低。

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.