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Microneurographic analysis of sympathetic nerve activity under weightlessness simulated by water immersion

水浸模拟失重状态下交感神经活动的显微神经图分析

基本信息

批准号：
61480113
负责人：
MANO Tadaaki
金额：
$ 3.84万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1988
项目状态：
已结题

项目摘要

The purpose of this research project was to clarify the neural controlling mechanisms of human body under weihjtlessness simulated by head-out water immersion. Subjects were 30 healthy volunteers ranging in age between 18 and 62. Effects of graded thermo-neutral water innersion up to the level of the neck of standing subject on sympathetic nerve activity, leg volume, cardiovascular and hormonal functions were analyzed. Muscle and skin sympathetic nerve activities (MSNA and SSNA) were recorded microneurographically from the tibial nerve. Leg volume was measured by rubber strain gauge plethysomgraphy. Heart rate, stroke volume, cardiac output, blood pressure and total peripheral resistance were measured as cardiovascular functions. Plasma catechoamines (epinephrine and norepinephrine), antidiuretic hormone(ADH), aldosterone, renin activity, angiotensin I・ II, atrial natriuretic polypeptide (ANP) were measured as homonal functions. 1. MSNA was strongly suppressed by head-out water immersion. However, this suppressive response of MSNA was less prominent in loder subjects than in younger ones. 2. SSNA was also suppressed by head-out water immersion. But this response was much weaker than that of MSNA. 3. Leg volume, heart rate and total peripheral resistance were reduced, while stroke volume and cardiac output were increased by head-out water immersion. Blood pressure was not significanty changed under the same condition. 4. Plasma catecholamines, ADH, aldosterone, renin activity, angiotensin I・ II were reduced, while ANP was markedly increased by head-out water immersion. Based on these findings, it is concluded that the suppressive response of MSNA plays an important role in cooperation with the hormonal responses to compensate cephalad fluid shift under weightlessness simulated by water immersion and to maintain hemodynamic homeostasis. This suppressive response of MSNA seems to be influenced by aging, becoming presumably less important in older subjects.

本研究的目的是阐明头外浸水模拟失重条件下人体的神经控制机制。受试者为30名健康志愿者，年龄在18至62岁之间。本文分析了在站立受试者颈部水平进行分级热中性水内洗对交感神经活动、腿部容积、心血管和激素功能的影响。肌肉和皮肤交感神经活动（MSNA和SSNA）从胫神经显微神经记录。用橡胶应变仪体积描记法测量下肢体积。心血管功能测定包括心率、每搏输出量、心输出量、血压和总外周阻力。分别测定血浆儿茶酚胺（肾上腺素和去甲肾上腺素）、抗利尿激素（ADH）、醛固酮、肾素活性、血管紧张素I· II、心钠素（ANP）等。1. MSNA被强烈抑制的头伸出水浸。然而，MSNA的这种抑制反应在年老受试者中不如年轻受试者突出。2. SSNA也被抑制的头出水浸。但这种反应比MSNA的反应弱得多。3.头外浸水使下肢容积、心率和总外周阻力降低，而每搏输出量和心输出量增加。在相同条件下，血压无明显变化。4.头外浸水可使血浆儿茶酚胺、ADH、醛固酮、肾素活性、血管紧张素I· II降低，而使血浆心钠素升高。基于这些研究结果，可以得出结论，MSNA的抑制反应起着重要的作用，在合作与激素的反应，以补偿头部液体转移下模拟失重水浸和维持血流动力学稳态。MSNA的这种抑制性反应似乎受到年龄的影响，在老年受试者中可能变得不那么重要。