男性卧床休息期间及卧床休息后直立位时的血管运动交感神经活动。

Vasomotor sympathetic nerve activity in men during bed rest and on orthostasis after bed rest.

作者信息

Kamiya A, Iwase S, Sugiyama Y, Mano T, Sudoh M

机构信息

Department of Autonomic Neuroscience, Research Institute of Environmental Medicine, Nagoya University, Japan.

出版信息

Aviat Space Environ Med. 2000 Feb;71(2):142-9.

PMID:10685588

Abstract

BACKGROUND

Alterations in autonomic function are commonly seen during and after spaceflight, and its ground-based analog, 6 degrees head-down bed rest (HDBR). They may include peripheral vascular regulation, but vasomotor sympathetic efferent nerve discharges to peripheral vasculatures have not been examined. The aim of our study was to examine changes in vasomotor sympathetic nerve activity during HDBR and under orthostasis after HDBR.

METHODS

We performed 6 d of HDBR on six male subjects, and measured muscle sympathetic nerve activity (MSNA) together with plasma norepinephrine concentrations in the supine position before HDBR and in 6 degrees head-down position on the sixth day (HDBR6) of HDBR. We also measured MSNA in head-up tilt (HUT) test before and after HDBR.

RESULTS

On HDBR6, MSNA burst rate was the same (17+/-4 bursts x min(-1)) as that in supine position before HDBR (15+/-2 bursts min(-1)), but plasma norepinephrine concentrations were decreased to 1.14+/-0.10 pmol x ml(-1) compared with the supine value before HDBR (1.56+/-0.20 pmol x ml(-1), p<0.05). After HDBR, supine MSNA burst rate significantly increased by 58% to 24+/-4 bursts x min(-1). MSNA increment in response to HUT was similar between before (34+/-3 bursts min(-1) x sin HUT(-1)) and after (40+/-6 bursts x min(-1) x sin HUT(-1)) HDBR.

CONCLUSIONS

Our findings suggest that: a) the relationship between MSNA and plasma norepinephrine concentrations was altered on the sixth day during HDBR; b) the vasomotor sympathetic nerve activity was enhanced after HDBR; and c) the augmentation of vasomotor sympathetic outflow to muscles under orthostasis was preserved after HDBR.

摘要

背景

自主神经功能改变在太空飞行期间及之后以及其地面模拟环境——头低位卧床休息（HDBR）6°时很常见。这些改变可能包括外周血管调节，但尚未对外周血管的血管运动交感传出神经放电进行研究。我们研究的目的是检查HDBR期间及HDBR后直立位时血管运动交感神经活动的变化。

方法

我们对6名男性受试者进行了6天的HDBR，并在HDBR前的仰卧位以及HDBR第6天（HDBR6）的头低位测量了肌肉交感神经活动（MSNA）以及血浆去甲肾上腺素浓度。我们还在HDBR前后的头高位倾斜（HUT）试验中测量了MSNA。

结果

在HDBR6时，MSNA爆发频率与HDBR前仰卧位时相同（17±4次爆发×分钟⁻¹），但血浆去甲肾上腺素浓度降至1.14±0.10 pmol×毫升⁻¹，与HDBR前仰卧位值（1.56±0.20 pmol×毫升⁻¹）相比，差异有统计学意义（p<0.05）。HDBR后，仰卧位MSNA爆发频率显著增加58%，达到24±4次爆发×分钟⁻¹。HDBR前后对HUT的MSNA增量相似（HDBR前为34±3次爆发×分钟⁻¹×sin HUT⁻¹，HDBR后为40±6次爆发×分钟⁻¹×sin HUT⁻¹）。