Pacific Northwest National Laboratory, Richland, Washington, United States of America.
PLoS One. 2012;7(7):e39685. doi: 10.1371/journal.pone.0039685. Epub 2012 Jul 25.
Metabolic processes result in the release and exchange of H and O atoms from organic material as well as some inorganic salts and gases. These fluxes of H and O atoms into intracellular water result in an isotopic gradient that can be measured experimentally. Using isotope ratio mass spectroscopy, we revealed that slightly over 50% of the H and O atoms in the intracellular water of exponentially-growing cultured Rat-1 fibroblasts were isotopically distinct from growth medium water. We then employed infrared spectromicroscopy to detect in real time the flux of H atoms in these same cells. Importantly, both of these techniques indicate that the H and O fluxes are dependent on metabolic processes; cells that are in lag phase or are quiescent exhibit a much smaller flux. In addition, water extracted from the muscle tissue of rats contained a population of H and O atoms that were isotopically distinct from body water, consistent with the results obtained using the cultured Rat-1 fibroblasts. Together these data demonstrate that metabolic processes produce fluxes of H and O atoms into intracellular water, and that these fluxes can be detected and measured in both cultured mammalian cells and in mammalian tissue.
代谢过程导致 H 和 O 原子从有机物质以及一些无机盐和气体中释放和交换。这些 H 和 O 原子流入细胞内水的通量会导致可在实验中测量的同位素梯度。使用同位素比质谱法，我们揭示了在指数生长培养的 Rat-1 成纤维细胞的细胞内水中，略超过 50%的 H 和 O 原子与生长培养基水的同位素不同。然后，我们采用红外光谱显微镜实时检测这些相同细胞中 H 原子的通量。重要的是，这两种技术都表明 H 和 O 通量取决于代谢过程；处于迟滞期或静止期的细胞表现出的通量要小得多。此外，从大鼠肌肉组织中提取的水含有一群 H 和 O 原子，它们与体液的同位素不同，这与使用培养的 Rat-1 成纤维细胞得到的结果一致。这些数据共同表明，代谢过程会将 H 和 O 原子通量带入细胞内水，并且这些通量可以在培养的哺乳动物细胞和哺乳动物组织中检测和测量。
