Renal and sympathoadrenal responses in space
Renal and sympathoadrenal responses in space
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DOI：
10.1053/ajkd.2001.27758
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发表时间：
2001-09-01
影响因子：
13.2
通讯作者：
Norsk, P
中科院分区：
文献类型：
--
作者：
Christensen, NJ;Drummer, C;Norsk, P
根据一个经典的假设，失重应该促进钠和水的肾脏排泄率，并导致液体和电解质耗尽状态。这一假设是基于实验，在这些实验中，人类通过头朝下卧床休息和浸水来模拟失重状态。然而，经过5至6天的空间使命，利尿剂和利钠反应静脉等渗盐水负荷减弱，血浆去甲肾上腺素和肾素浓度增加，与急性仰卧位飞行前。口服水负荷后的肾液排泄也在太空中减弱。在头低位卧床休息期间未观察到类似的降低。交感神经活动在调节血容量和肾功能方面具有重要意义。在空间进行的研究表明，与在地球上仰卧时相比，使用血浆中去甲肾上腺素和肾上腺素的浓度和尿排泄量来测量，空间飞行期间交感肾上腺活动增加。空间诱导的抗心房利尿机制和交感肾上腺活性的激活可能是由早期飞行中总血容量和中心血容量的减少引起的。血浆容量减少可能是由于血浆从下半身重新分布到上半身（腿细和脸肿）、食物摄入减少和肌肉活动减少等因素。血浆量减少和随后交感神经活动增加至少部分是由于微重力期间大肌肉群的活动突然停止，这通常抵消了直立姿势的重力影响。这将导致白蛋白和液体在组织间隙中蓄积。(C)2001年由国家肾脏基金会，公司。
According to a classic hypothesis, weightlessness should promote the renal excretion rate of sodium and water nd lead to a fluid- and electrolyte-depleted state. This hypothesis is based on experiments in which weightlessness has been simulated in humans by head-down bed rest and water immersion. However, after 5 to 6 days of space mission, the diuretic and natriuretic responses to an intravenous isotonic saline load were attenuated and plasma norepinephrine and renin concentrations increased compared with those of the acute supine position before flight. Renal fluid excretion after an oral water load was also attenuated in space. Similar decreases were not observed during head-down bed rest. Sympathetic activity is of major importance in regulating blood volume and renal function. Studies in space have indicated that, compared with that while in a supine position on Earth, sympathoadrenal activity is increased during space flights as measured using plasma concentration and urinary excretion of norepinephrine and epinephrine. The space-induced activation of antinatriuretic mechanisms and sympathoadrenal activity could have been caused by early in-flight reduction in total and central blood volume. The decreased plasma volume may be explained by such factors as redistribution of plasma from the lower to the upper body (thin legs and puffy face), reduced food intake, and decreased muscle activity. The decrease in plasma volume and the subsequent increase in sympathetic activity is due, at least in part, to the abrupt cessation of activity in large muscle groups during microgravity, which normally counteracts the effects of gravity in the upright posture. This would lead to accumulation of albumin and fluid in the interstitial space. (C) 2001 by the National Kidney Foundation, Inc.