Suenson M, Richmond D R, Bassingthwaighte J B
Am J Physiol. 1974 Nov;227(5):1116-23. doi: 10.1152/ajplegacy.1974.227.5.1116.
The cumulative fluxes of radioactive sucrose, sodium, and water across a sheet of cat right ventricle were studied simultaneously to obtain the apparent tissue diffusion coefficients for extravascular diffusion at 37°C. The sucrose data fitted the equations for diffusion in tortuous channels in a plane sheet with a tortuosity factor, λ, of 2.11 ± 0.11 (mean ± SE, = 10). The fit of the earliest data before attainment of steady state was improved by assuming a Gaussian distribution of diffusion path lengths through the extracellular space, but λ was only changed by a few percent. The sucrose diffusion channel contained 0.27 ± 0.03 ml of total tissue water, which is more than measured by others but still less than the expected sucrose space. The steady-state data for sodium agreed with the model for extracellular diffusion using λ and the area available for diffusion for sucrose when sodium equilibration with a dead-end pore volume (presumed to be intracellular) was taken into account. The cumulative flux data for water were monotonic and lacked secondary inflections. Thus the apparent tissue diffusion coefficients for sucrose, sodium, and water were (in 10 cm/s) 1.77 ± 0.23, 5.13 ± 0.68, and 7.39 ± 0.99, respectively, representing a reduction to 23% of the free diffusion coefficient for sucrose and sodium and 22% for water.
同时研究了放射性蔗糖、钠和水通过猫右心室片的累积通量，以获得37℃下血管外扩散的表观组织扩散系数。蔗糖数据符合平面片中曲折通道中扩散的方程，曲折因子λ为2.11±0.11（平均值±标准误，n = 10）。通过假设穿过细胞外空间的扩散路径长度呈高斯分布，改善了达到稳态之前最早数据的拟合，但λ仅改变了几个百分点。蔗糖扩散通道包含0.27±0.03 ml的总组织水，这比其他人测量的要多，但仍小于预期的蔗糖空间。当考虑到钠与死端孔体积（假定为细胞内）平衡时，钠的稳态数据与使用λ和蔗糖可用于扩散的面积的细胞外扩散模型一致。水的累积通量数据是单调的，没有二次拐点。因此，蔗糖、钠和水的表观组织扩散系数（单位为10⁻⁵ cm²/s）分别为1.77±0.23、5.13±0.68和7.39±0.99，这表明蔗糖和钠的扩散系数降至自由扩散系数的23%，水降至22%。
