VESTIBULOSYMPATHETIC REFLEXES IN HUMANS

描述(改编自申请人的摘要)：长期 首席调查员的目标是评估反射机制 调节人体心血管系统的物质。调查员已经 最近证明，头向下的颈部屈曲(HDNF)可以增加肌肉 交感神经活动(MSNA)。这一发现表明， 前庭系统对MSNA的调节。总体假设是 在这个项目中评价的是，前庭系统起着重要的作用 在人类交感神经系统调节中的作用。这 假说将通过在激活过程中记录人类的MSNA来评估 通过不同的头部运动来控制前庭系统。在这份提案中， 将检验以下假设：1.在HDNF期间MSNA的增加是 由于前庭的激活。2.耳石器官，但不是半圆形 运河会引起MSNA的增加。3.激活前庭交感神经 反射调节由其他心血管反射引起的MSNA。为了测试 提出这些假设、研究的具体目的有以下几点：1. 在不同水平和持续时间内确定MSNA对HDNF的响应 颈部屈曲，并在不同的身体位置进行。2.确定 在激活耳石的动态头部运动中的MSNA反应 器官和半规管。3.确定HDNF的相互作用 (前庭交感神经反射)与其他心血管反射(例如， 动脉压力感受性反射)。这些研究的设计将 提供有关交感神经前庭调节的新知识 人类的活动。这些发现可能会对 了解健康人群直立不耐受的原因 受试者以及为什么直立不耐受在老年人中更普遍 以及长期暴露在微重力下的个体。

DESCRIPTION (Adapted from the applicant's abstract): The long-term objectives of the Principal Investigator are to evaluate reflex mechanisms that regulate the cardiovascular system in humans. The investigator has recently demonstrated that head-down neck flexion (HDNF) increases muscle sympathetic nerve activity (MSNA). This finding suggested a role of the vestibular system in regulating MSNA. The overall hypothesis to be evaluated in this project is that the vestibular system plays an important role in the regulation of the sympathetic nervous system in humans. This hypothesis will be evaluated by recording MSNA in humans during activation of the vestibular system by different head movements. In this proposal the following hypotheses will be tested: 1. Increases in MSNA during HDNF are due to vestibular activation. 2. Otolith organs but not semicircular canals elicit increases in MSNA. 3. Activation of the vestibulosympathetic reflex modulates MSNA elicited by other cardiovascular reflexes. To test these hypotheses, studies with the following specific aims are proposed: 1. To determine MSNA responses to HDNF during different levels and durations of neck flexion, and performed in different body positions. 2. To determine MSNA responses during dynamic head movements which activate both the otolith organs and semicircular canals. 3. To determine the interaction of HDNF (vestibulosympathetic reflex) with other cardiovascular reflexes (e.g., arterial baroreflex) on MSNA in humans. The design of these studies will provide new knowledge regarding vestibular regulation of sympathetic activity in humans. These findings may have important implications in understanding the cause of orthostatic intolerance in otherwise healthy subjects and why orthostatic intolerance is more prevalent in the elderly and in individuals following prolonged exposure to microgravity.