Vestibulosympathetic Reflexes in Humans

人类前庭交感神经反射

• 批准号: 6870181
• 负责人: CHESTER A RAY
• 金额: $ 27.25万
• 依托单位: PENNSYLVANIA STATE UNIV HERSHEY MED CTR
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-04-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6870181
• 关键词: Vestibulosympathetic; Reflexes; Humans

DESCRIPTION (provided by applicant): The long-term objective of the Principal Investigator is to evaluate vestibular reflex mechanisms that regulate the cardiovascular system in humans. During the past funding period, we demonstrated that activation of the otolith organs mediated prompt and marked increases in sympathetic nerve activity and limb vascular resistance. The main hypothesis for this project is that the vestibulosympathetic reflex participates importantly in orthostasis by activating the sympathetic nervous system in humans. It is hypothesized that attenuations in the vestibulosympathetic reflex contributes to orthostatic intolerance in humans. To test these hypotheses, we propose studies with the following specific aims: 1. To determine muscle sympathetic nerve activity (MSNA) responses during dynamic pitch rotation. Transition from the supine to upright posture and ambulation dynamically stimulate the otolith organs Therefore, it is important to determine whether dynamic activation of the otolith organs elicits increases in sympathetic vasoconstrictor outflow. We hypothesize greater increases in MSNA will be elicited by dynamic rather than static engagement of the otolith organs. 2. To determine MSNA responses to otolith organ stimulation in the prone, sitting, and upright positions. Because postural blood pressure control is most important in the upright posture, we will test the vestibulosympathetic reflex during head rotations in the sitting and standing positions. We hypothesize that increases in MSNA by the vestibulosympathetic reflex via head-down rotation is independent of body posture. 3. To determine visceral vascular responses to static head-down rotation. Because visceral vascular vasoconstriction contributes importantly to postural blood pressure regulation, we hypothesize that vestibular activation will mediate increases in visceral vascular resistance. 4. To examine sympathetic and hemodynamic responses to otolith organ stimulation in subjects with a predisposition to orthostatic intolerance. We hypothesize that MSNA responses will be attenuated and blood pressure reduced during activation of the vestibulosympathetic in subjects with orthostatic intolerance (i.e., vestibular deficient and idiopathic orthostatic hypotension subjects, and endurance trained athletes). The design of these studies will increase our understanding of how the vestibular system contributes to orthostatic blood pressure regulation in humans.

描述（由申请人提供）：主要研究者的长期目标是评价调节人类心血管系统的前庭反射机制。在过去的资助期间，我们证明了耳石器官的激活介导交感神经活动和肢体血管阻力的迅速和显着增加。该项目的主要假设是前庭交感神经反射通过激活人类的交感神经系统而重要地参与直立。据推测，前庭交感神经反射的衰减有助于人类的立位不耐受。为了验证这些假设，我们提出了以下具体目标的研究：1。目的：测定动态俯仰旋转过程中肌肉交感神经活动（MSNA）的反应。从仰卧位到直立位的过渡和腋生动态地刺激耳石器官。因此，确定耳石器官的动态激活是否会增加交感血管收缩剂的流出是重要的。我们推测，更大的MSNA增加将引起动态而不是静态的耳石器官的参与。 2.确定在俯卧位、坐位和直立位刺激耳石器官时MSNA的反应。由于体位血压控制在直立姿势中最为重要，我们将测试在坐姿和站姿下头部旋转时的前庭交感神经反射。我们假设，通过头向下旋转前庭交感神经反射增加MSNA是独立的身体姿势。 3.确定静态头向下旋转时内脏血管的反应。由于内脏血管收缩对体位性血压调节有重要作用，我们假设前庭激活将介导内脏血管阻力的增加。 4.研究有立位不耐受倾向的受试者对耳石器官刺激的交感神经和血流动力学反应。我们假设，在直立不耐受的受试者中，MSNA反应将在前庭交感神经激活期间减弱，血压降低（即，前庭缺陷和特发性直立性低血压受试者和耐力训练的运动员）。 这些研究的设计将增加我们对前庭系统如何促进人类直立性血压调节的理解。