神经元和星形胶质细胞细胞内水预交换寿命。
Intracellular water preexchange lifetime in neurons and astrocytes.
机构信息
Department of Chemistry, Washington University, St. Louis, Missouri, USA.
Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
出版信息
Magn Reson Med. 2018 Mar;79(3):1616-1627. doi: 10.1002/mrm.26781. Epub 2017 Jul 4.
PURPOSE
To determine the intracellular water preexchange lifetime, τ , the "average residence time" of water, in the intracellular milieu of neurons and astrocytes. The preexchange lifetime is important for modeling a variety of MR data sets, including relaxation, diffusion-sensitive, and dynamic contrast-enhanced data sets.
METHODS
Herein, τ in neurons and astrocytes is determined in a microbead-adherent, cultured cell system. In concert with thin-slice selection, rapid flow of extracellular media suppresses extracellular signal, allowing determination of the transcytolemmal-exchange-dominated, intracellular T . With this knowledge, and that of the intracellular T in the absence of exchange, τ can be derived.
RESULTS
Under normal culture conditions, τ for neurons is 0.75 ± 0.05 s versus 0.57 ± 0.03 s for astrocytes. Both neuronal and astrocytic τ s decrease within 30 min after the onset of oxygen-glucose deprivation, with the astrocytic τ showing a substantially greater decrease than the neuronal τ .
CONCLUSIONS
Given an approximate intra- to extracellular volume ratio of 4:1 in the brain, these data imply that, under normal physiological conditions, an MR experimental characteristic time of less than 0.012 s is required for a nonexchanging, two-compartment (intra- and extracellular) model to be valid for MR studies. This characteristic time shortens significantly (i.e., 0.004 s) under injury conditions. Magn Reson Med 79:1616-1627, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
目的
确定神经元和星形胶质细胞细胞内水的预交换寿命 τ，即水在细胞内环境中的“平均停留时间”。预交换寿命对于建模各种磁共振（MR）数据集（包括弛豫、扩散敏感和动态对比增强数据集）非常重要。
方法
在此，通过微珠附着的培养细胞系统确定神经元和星形胶质细胞中的 τ。与薄片选择相结合，细胞外介质的快速流动抑制细胞外信号，允许确定跨细胞膜交换主导的细胞内 T。有了这些知识，以及在没有交换的情况下细胞内 T 的知识，可以推导出 τ。
结果
在正常培养条件下，神经元的 τ 为 0.75±0.05 s，而星形胶质细胞的 τ 为 0.57±0.03 s。在缺氧葡萄糖剥夺开始后 30 分钟内，神经元和星形胶质细胞的 τ 均降低，星形胶质细胞的 τ 降低幅度明显大于神经元的 τ。
结论
鉴于大脑中细胞内到细胞外的体积比约为 4:1，这些数据表明，在正常生理条件下，对于 MR 研究，一个无交换的两室（细胞内和细胞外）模型，其 MR 实验特征时间小于 0.012 s 才有效。在损伤条件下，这个特征时间会显著缩短（即 0.004 s）。磁共振医学 79：1616-1627，2018。©2017 国际磁共振学会。
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