Bakay L, Kurland R J, Parrish R G, Lee J C, Peng R J, Bartkowski H M
Exp Brain Res. 1975 Sep 29;23(3):241-8. doi: 10.1007/BF00239737.
The nmr relaxation rate results show unequivocally that there are at least two fractions of tissue water in both normal and edematous white matter which do not exchange on an nmr time scale (i.e. at times of the order of milli-seconds to fraction of a second). In conjunction with the electron microscopic determination of the extracellular volumes of normal and edematous white matter, the relaxation results can be interpreted in terms of the following model. The two slowly-exchanging water components giving rise to the non-exponential relaxation correspond to cellular and extracellular water; edema changes the relaxation rate of the extracellular component much more than that of the cellular component (the extracellular component becoming more "liquid-like" in its relaxation). Such behavior is consistent with the properties of the extracellular water being due to rapid exchange between motionally restricted water adsorbed at the surface of myelin sheaths, and relatively unrestricted, bulk water. Edema presumably increases the relative amount of the "bulk" water between the axons.
核磁共振弛豫率结果明确显示，在正常和水肿的白质中至少存在两部分组织水，它们在核磁共振时间尺度上（即从毫秒到几分之一秒的时间量级）不发生交换。结合对正常和水肿白质细胞外体积的电子显微镜测定，弛豫结果可根据以下模型进行解释。产生非指数弛豫的两个缓慢交换的水成分分别对应细胞内水和细胞外水；水肿对细胞外成分弛豫率的改变远大于对细胞内成分弛豫率的改变（细胞外成分在弛豫方面变得更“像液体”）。这种行为与细胞外水的性质一致，细胞外水的性质是由于吸附在髓鞘表面的运动受限水与相对不受限的大量水之间的快速交换所致。水肿可能增加了轴突之间“大量”水的相对含量。
