Chavarri M, Ganguly A, Luetscher J A, Zager P G
Aviat Space Environ Med. 1977 Jul;48(7):633-6.
Previous studies of normal men after 5 d of bedrest showed that circulatory instability on head-up tilt or standing is preceded by increased plasma renin activity (PRA) at bedrest. In the present study, the circadian rhythms of PRA, aldosterone, and cortisol have been observed in five normal men on a constant diet. In ambulatory controls, PRA and aldosterone increased normally after standing. On the third morning of bedrest, PRA was higher than before, and at noon, PRA was higher than in standing controls. The nocturnal peaks of PRA resulting from episodic renin secretion during sleep were higher after bedrest. Plasma aldosterone was also increased by bedrest. The findings are compatible with the theory that intermittent beta-adrenergic nerve activity during sleep is increased after bedrest, but other factors, such as loss of body sodium and a lower plasma volume, may also be involved.
先前对正常男性进行5天卧床休息后的研究表明，在卧床休息时血浆肾素活性（PRA）升高之后，会出现头高位倾斜或站立时的循环不稳定。在本研究中，观察了5名饮食恒定的正常男性体内PRA、醛固酮和皮质醇的昼夜节律。在动态对照组中，站立后PRA和醛固酮正常升高。卧床休息的第三天早晨，PRA高于之前，中午时，PRA高于站立对照组。睡眠期间间歇性肾素分泌导致的PRA夜间峰值在卧床休息后更高。卧床休息也使血浆醛固酮增加。这些发现与以下理论相符：卧床休息后睡眠期间间歇性β-肾上腺素能神经活动增加，但其他因素，如身体钠流失和较低的血浆容量，也可能起作用。
