aInterdisciplinary Center for Clinical Research and Department of Nephrology and Hypertension, Friedrich-Alexander-University, Erlangen-Nürnberg, Germany bDivision of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
Curr Opin Nephrol Hypertens. 2014 Mar;23(2):101-5. doi: 10.1097/01.mnh.0000441151.55320.c3.
The equilibration theory of extracellular body fluids is tightly linked to sodium (Na) metabolism. It is accepted that with changes in salt intake, renal sodium elimination will prevent any change in interstitial Na content and concentration. This review summarizes recent anomalous findings regarding salt and water homeostasis that are inconsistent with current assumptions.
Recent findings from chemical analysis studies of laboratory animals, as well as noninvasive quantitative Na MRI (Na-MRI) studies in patients, have shown that remarkable amounts of Na are stored in muscle and in skin without commensurate water retention. Furthermore, an ultra-long Na balance study in humans suggests the presence of endogenous clocks that generate weekly and monthly infradian rhythmicity of Na storage independent of salt intake. Animal experiments suggest that fluids in the skin interstitium are hypertonic compared with plasma, and that interstitial osmotic stress induces local extrarenal immune cell and lymph-capillary driven mechanisms for electrolyte clearance and maintenance of the internal environment.
Recent quantitative evidence challenges current ideas on salt and water homeostasis, and suggests that Na homeostasis cannot be maintained without additional previously unappreciated extrarenal regulatory mechanisms.
细胞外体液平衡理论与钠（Na）代谢密切相关。人们普遍认为，随着盐摄入量的变化，肾脏会排出钠，以防止间质 Na 含量和浓度发生任何变化。本综述总结了最近关于盐和水稳态的异常发现，这些发现与当前的假设不一致。
来自实验室动物化学分析研究以及患者非侵入性定量 Na MRI（Na-MRI）研究的最新发现表明，大量的 Na 储存在肌肉和皮肤中，而没有相应的水潴留。此外，一项针对人类的超长 Na 平衡研究表明，存在内源性生物钟，可产生独立于盐摄入量的每周和每月亚昼夜节律性 Na 储存。动物实验表明，与血浆相比，皮肤间质中的液体呈高渗状态，间质渗透压应激会引起局部肾外免疫细胞和淋巴毛细血管驱动的电解质清除和内部环境维持机制。
最近的定量证据挑战了当前关于盐和水稳态的观点，并表明，如果没有以前未被认识到的额外的肾外调节机制，就不能维持 Na 稳态。
