Pollack G L
Biophys J. 1977 Jul;19(1):49-62. doi: 10.1016/S0006-3495(77)85561-6.
We have measured the total permeability coefficients P as a function of stirring frequency omega for 133Xe through frog skins and toad bladders. The permeability coefficients for the frog skins and toad bladders proper are, respectively, Pm = (3.9 +/- 0.8) X 10(-4) cm/s and (7.4 +/- 4.2) X 10(-4) cm/s. "Unstirred" water layer thickness delta is determined concurrently, from the frequency dependence of P(omega); the result for frog skin is delta = (0.060 +/- 0.016) square root of omega(rad/s) cm. The stirring frequency range is from omega = 7.5 rad/s (72 rpm) to 55 rad/s (530 rpm). The results support the conclusions that the principal barrier to Xe diffusion in these epithelia is inter- and intracellular water, and that the diffusion is passive and rapid. The experimental method may be straightforwardly adapted to the measurement of diffusion or counterdiffusion of any gamma-radioactive soluble or partly soluble solute through any flat membrane or through a solvent. We estimate the amount of total body-absorbed radioactivity due to environmental 133Xe to be 50 fCi for an ambient concentration of 2.6 pCi/m3 of air.
我们测量了133Xe通过蛙皮和蟾蜍膀胱的总渗透系数P随搅拌频率ω的变化。蛙皮和蟾蜍膀胱本身的渗透系数分别为Pm = (3.9 ± 0.8)×10⁻⁴ cm/s和(7.4 ± 4.2)×10⁻⁴ cm/s。同时，根据P(ω)的频率依赖性确定“未搅拌”水层厚度δ；蛙皮的结果是δ = (0.060 ± 0.016)√ω(rad/s) cm。搅拌频率范围是从ω = 7.5 rad/s（72转/分钟）到55 rad/s（530转/分钟）。这些结果支持以下结论：在这些上皮细胞中，Xe扩散的主要屏障是细胞间和细胞内的水，并且扩散是被动且快速的。该实验方法可以直接用于测量任何γ放射性可溶性或部分可溶性溶质通过任何扁平膜或通过溶剂的扩散或逆向扩散。对于空气中2.6 pCi/m³的环境浓度，我们估计由于环境中的133Xe导致的全身吸收放射性量为50 fCi。
