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Gender and Orthostatic Tolerance

性别和直立耐受性

基本信息

批准号：
6354448
负责人：
WILLIAM H COOKE
金额：
$ 9.95万
依托单位：
MICHIGAN TECHNOLOGICAL UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2001
资助国家：
美国
起止时间：
2001-08-17 至 2003-08-15
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/6354448
关键词：
cardiovascular disorder diagnosis cardiovascular function clinical research female gender difference human subject male menstrual cycle physiologic stressor postural hypotension posture pulmonary respiration respiratory airway pressure syncope

项目摘要

DESCRIPTION (provided by applicant): Orthostatic tolerance is defined by the ability to maintain adequate arterial pressure and cerebral perfusion despite head-to-foot fluid shifts induced by standing or lower body negative pressure (LBNP). Syndromes such as neuro-cardiogenic syncope afflict thousands of apparently normal, healthy people every day, and greater than 50% of astronauts returning from space cannot stand passively for 10 minutes. The etiology of orthostatic intolerance is multi-factorial, but the condition is likely related to one or more of the following: 1) malfunction of arterial baroreceptors; 2) inappropriate autonomic cardiac regulation; 3) relative hypovolemia; 4) inadequate sympathetic nervous system activation; and/or 5) inadequate peripheral vascular responsiveness to sympathetic stimulation. To complicate matters, women seem to experience orthostatic intolerance to a greater extent than men. Women develop greater cardioacceleration during LBNP compared with men, less systemic vasoconstriction, and greater blood pooling in the pelvic region. Circulating estrogen levels, through activation of vasodilators such as nitric oxide, have also been implicated as a contributing factor. Therefore, the global objective of this proposal is to identify differences in cardiovascular responses to orthostatic stress between men and women, and between women during different phases of their menstrual cycle. To study the influence of gender on orthostatic tolerance, males and females will be directly compared, and the same females will be compared during different phases of their menstrual cycle with the following tests: 1) controlled frequency breathing; 2) Valsalva's maneuver; and 3) LBNP. Beat-to beat R-R interval, arterial pressure, body fluid distribution, and muscle sympathetic nerve activity will be measured during all protocols. These minimally invasive, highly integrated tests of autonomic cardiovascular control will inform fundamental cardiovascular mechanisms during orthostatic challenges, and will highlight differences associated with gender and menstrual phase. The results of the proposed research could lead to advances in the terrestrial treatment of neuro-cardiogenic syncope, and to gender-specific countermeasures to the cardiovascular deconditioning that occurs in astronauts in space. As an additional specific aim, the research is designed in large part to allow undergraduate students to receive an invaluable introduction to research.

描述（由申请人提供）：立位公差由维持足够的动脉压和脑灌注的能力，站立或下体负压引起的头到脚液体转移（黎巴嫩国家银行）。神经心源性晕厥等晕厥折磨着成千上万的每天都有健康的人，超过50%的宇航员从太空回来不能被动地站十分钟。的病因直立不耐受是多因素的，但条件可能是相关的以下一种或多种：1）动脉压力感受器功能障碍; 2）不适当的自主心脏调节; 3）相对低血容量; 4）交感神经系统激活不充分;和/或5）不充分外周血管对交感神经刺激的反应性。复杂化问题是，女性似乎在更大程度上经历了直立性不耐受而不是男人。女性在LBNP期间的心脏加速程度高于男性，全身血管收缩较少，盆腔血液淤积较多地区循环雌激素水平，通过激活血管扩张剂，一氧化氮也被认为是一个促成因素。因此，我们认为，本建议的总体目标是确定以下方面的差异：男性和女性对直立性应激的心血管反应，以及女性在月经周期的不同阶段。研究性别对立位耐力的影响，男性和女性将直接比较，相同的女性将在不同的时间进行比较，她们的月经周期的阶段与以下测试：1）控制频率呼吸; 2）Valsalva动作;和3）LBNP。拍-拍R-R 间隔、动脉压、体液分布和肌肉交感神经将在所有方案期间测量神经活动。这些微创手术自主心血管控制的高度综合测试将告知立位挑战期间的基本心血管机制，并将强调了与性别和月经期相关的差异。结果拟议的研究可能会导致陆地处理的进展，神经心源性晕厥，并采取针对性别的对策，发生在太空宇航员身上的心血管失调。作为另外，研究的目的在很大程度上是为了让本科生将获得宝贵的研究介绍。