The measurement of fluid compartmentalization, or the distribution of fluid volume between extracellular (ECF) and intracellular (ICF) spaces, historically requires complicated, burdensome, and often terminal methodologies that do not permit repeated or longitudinal experiments. New technologies including time-domain nuclear magnetic resonance (TD-NMR)-based methods allow for highly accurate measurements of total body water (TBW) within minutes in a non-invasive manner, but do not permit dissection of ECF versus ICF reservoirs. In contrast, methods such as bioimpedance spectroscopy (BIS) allow dissection of ECF versus ICF reservoirs but are hampered by dependence upon many nuanced details in data collection which undermine confidence in experimental results. Here, we present a novel combinatorial use of these two technologies (NMR/BIS) to improve the accuracy of BIS-based assessments of ECF and ICF, while maintaining the advantages of these minimally-invasive methods. Briefly, mice undergo TD-NMR and BIS-based measures, and then fat masses as derived by TD-NMR are used to correct BIS outputs. Mice of the C57BL/6J background were studied using NMR/BIS methods to assess the effects of acute furosemide injection and diet-induced obesity upon fluid compartmentalization, and to examine the influence of sex, body mass and composition, and diet upon TBW, ECF, and ICF. We discovered that in mice, sex and body size/composition have substantial and interactive effects upon fluid compartmentalization. We propose that the combinatorial use of NMR/BIS methods will enable a revisioning of the types of longitudinal, kinetic studies that can be performed to understand the impact of various interventions upon body fluid homeostasis.

中文翻译：

---

结合时域核磁共振和生物阻抗谱对体液区室化进行量化

流体分隔或细胞外 (ECF) 和细胞内 (ICF) 空间之间的流体体积分布的测量历来需要复杂、繁重且通常是不允许重复或纵向实验的终端方法。包括基于时域核磁共振 (TD-NMR) 的方法在内的新技术允许以非侵入性方式在几分钟内高度准确地测量全身水分 (TBW)，但不允许解剖 ECF 与 ICF 水库。相比之下，生物阻抗谱 (BIS) 等方法允许对 ECF 与 ICF 储层进行剖析，但由于依赖数据收集中许多细微的细节而受到阻碍，这会破坏对实验结果的信心。这里，我们提出了这两种技术 (NMR/BIS) 的新型组合使用，以提高基于 BIS 的 ECF 和 ICF 评估的准确性，同时保持这些微创方法的优势。简而言之，小鼠接受 TD-NMR 和基于 BIS 的测量，然后使用 TD-NMR 得出的脂肪量来校正 BIS 输出。使用 NMR/BIS 方法研究 C57BL/6J 背景的小鼠，以评估急性呋塞米注射和饮食诱导的肥胖对液体分隔的影响，并检查性别、体重和成分以及饮食对 TBW、ECF 的影响和 ICF。我们发现，在小鼠中，性别和体型/成分对液体区室化有实质性的相互作用影响。我们建议 NMR/BIS 方法的组合使用将使纵向类型的修订成为可能，