Seeliger Erdmann, Ladwig Mechthild, Reinhardt H Wolfgang
Institut für Physiologie, Charité Universitätsmedizin Berlin CCM, Tucholskystr. 2, 10117 Berlin, Germany.
Am J Physiol Regul Integr Comp Physiol. 2006 May;290(5):R1429-35. doi: 10.1152/ajpregu.00676.2005. Epub 2005 Dec 22.
Alterations in total body sodium (TBSodium) that covered the range from moderate deficit to large surplus were induced by 10 experimental protocols in 66 dogs to study whether large amounts of Na+ are stored in an osmotically inactive form during Na+ retention. Changes in TBSodium, total body potassium (TBPotassium), and total body water (TBWater) were determined by 4-day balance studies. A rather close correlation was found between individual changes in TBSodium and those in TBWater (r2 = 0.83). Changes in TBSodium were often accompanied by changes in TBPotassium. Taking changes of both TBSodium and TBPotassium into account, the correlation with TBWater changes became very close (r2 = 0.93). The sum of changes in TBSodium and TBPotassium was accompanied by osmotically adequate TBWater changes, and plasma osmolality remained unchanged. Calculations reveal that even moderate TBSodium changes often included substantial Na+/K+ exchanges between extracellular and cellular space. The results support the theory that osmocontrol effectively adjusts TBWater to the body's present content of the major cations, Na+ and K+, and do not support the notion that, during Na+ retention, large portions of Na+ are stored in an osmotically inactive form. Furthermore, the finding that TBSodium changes are often accompanied by TBPotassium changes and also include Na+/K+ redistributions between fluid compartments suggests that cells may serve as readily available Na+ store. This Na+ storage, however, is osmotically active, since osmotical equilibration is achieved by opposite redistribution of K+.
通过10种实验方案在66只犬身上诱导出全身钠（TBSodium）从适度缺乏到大量过剩的变化，以研究在钠潴留期间大量钠离子是否以渗透惰性形式储存。通过为期4天的平衡研究来测定TBSodium、全身钾（TBPotassium）和全身水（TBWater）的变化。发现TBSodium的个体变化与TBWater的个体变化之间存在相当密切的相关性（r2 = 0.83）。TBSodium的变化常常伴随着TBPotassium的变化。综合考虑TBSodium和TBPotassium的变化，与TBWater变化的相关性变得非常密切（r2 = 0.93）。TBSodium和TBPotassium变化的总和伴随着渗透上适当的TBWater变化，血浆渗透压保持不变。计算结果表明，即使是适度的TBSodium变化通常也包括细胞外和细胞内空间之间大量的Na+/K+交换。这些结果支持了渗透控制能有效地使TBWater适应身体目前主要阳离子Na+和K+含量的理论，并不支持在钠潴留期间大部分钠离子以渗透惰性形式储存的观点。此外，TBSodium变化常常伴随着TBPotassium变化且还包括液体隔间之间的Na+/K+重新分布这一发现表明细胞可能作为随时可用的钠离子储存库。然而，这种钠离子储存是渗透活性的，因为通过钾离子的相反重新分布实现了渗透平衡。
