See Article by Nijst et al Few will argue against the central role of salt in fluid volume and blood pressure homeostasis—a role that has passed the test of time through classical studies linking blood pressure and Na+ balance,1 also placing the kidney in the very center of extracellular fluid volume and blood pressure homeostasis.2 This fact notwithstanding, a role for other tissues like the interstitium, mostly in skin, has more recently been suggested in an increasing number of studies.3 Indeed, already Guyton et al4 proposed that strongly negatively charged mucopolysaccharides (now named glycosaminoglycans [GAGs]) could attract and thereby generate a higher density of cations, notably Na+, and that “tissue fluids, pressures, and gel” could influence overall regulation of circulation.5 There are 2 major types of GAGs, hyaluronan having 1 charge and sulfated GAGs having ≤3 charges per disaccharide unit.6 At physiological pH, GAGs have a net negative charge, thus attracting counterions. Although there existed data showing Na+ accumulation in skin, thus challenging the commonly accepted sodium homeostasis principle,7 this challenge was brought to a new level by Titze et al who introduced a new paradigm with regard to salt handling in the body. In studies from humans, rats, and mice, they showed that Na+ can be buffered in the body in kidney-independent reservoirs. This occurs without commensurate water retention, thereby making the Na+ osmotically inactive by association with negatively charged GAGs and thereby invisible to the kidney. In a series of studies, they demonstrated that the skin acts as kidney-independent regulator of the release and storage of Na+, for example,8 making the interstitium and its extracellular matrix and gel phase an additional player in Na+ homeostasis. Without questioning the undisputed role of …

中文翻译：

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从外部调节流体量

每个二糖单元含1个电荷的透明质酸和2个≤3个电荷的硫酸化GAG。6在生理pH值下，GAG具有净负电荷，因此会吸引抗衡离子。尽管已有数据显示Na +在皮肤中的蓄积，从而挑战了公认的钠稳态原理7，但Titze等人将这一挑战推向了一个新的高度，他们提出了有关体内盐处理的新范例。在对人，大鼠和小鼠的研究中，他们表明Na +可以在不依赖肾脏的储库中被体内缓冲。发生这种情况时没有适当的保水率，从而通过与带负电荷的GAG结合使Na +渗透失活，从而对肾脏不可见。在一系列研究中，他们证明皮肤可作为肾脏独立控制Na +释放和储存的调节剂，例如，8使间质及其细胞外基质和凝胶相成为Na +稳态中的另一个角色。毫无疑问……