Interdisciplinary Center for Clinical Research, Friedrich-Alexander-University, Erlangen-Nürnberg, Glückstrasse 6, D-91054 Erlangen, Germany.
Cell Metab. 2013 Jan 8;17(1):125-31. doi: 10.1016/j.cmet.2012.11.013.
The steady-state concept of Na(+) homeostasis, based on short-term investigations of responses to high salt intake, maintains that dietary Na(+) is rapidly eliminated into urine, thereby achieving constant total-body Na(+) and water content. We introduced the reverse experimental approach by fixing salt intake of men participating in space flight simulations at 12 g, 9 g, and 6 g/day for months and tested for the predicted constancy in urinary excretion and total-body Na(+) content. At constant salt intake, daily Na(+) excretion exhibited aldosterone-dependent, weekly (circaseptan) rhythms, resulting in periodic Na(+) storage. Changes in total-body Na(+) (±200-400 mmol) exhibited longer infradian rhythm periods (about monthly and longer period lengths) without parallel changes in body weight and extracellular water and were directly related to urinary aldosterone excretion and inversely to urinary cortisol, suggesting rhythmic hormonal control. Our findings define rhythmic Na(+) excretory and retention patterns independent of blood pressure or body water, which occur independent of salt intake.
基于对高盐摄入反应的短期研究，钠（Na+）稳态的概念认为膳食中的 Na+会迅速排泄到尿液中，从而保持体内总 Na+和水分的含量恒定。我们通过将参与太空飞行模拟的男性的盐摄入量固定在 12 克、9 克和 6 克/天数月，并测试尿液排泄和体内总 Na+含量的预测恒定性，引入了相反的实验方法。在盐摄入量恒定的情况下，每日 Na+排泄表现出醛固酮依赖性的每周（circaseptan）节律，导致周期性的 Na+储存。体内总 Na+（±200-400 mmol）的变化表现出更长的 infradian 节律周期（约每月和更长的周期长度），而体重和细胞外液没有平行变化，并且与尿醛固酮排泄直接相关，与尿皮质醇呈负相关，提示存在节律性激素控制。我们的发现定义了与血压或体液无关的、独立于盐摄入的节律性 Na+排泄和保留模式。
