Naito S, Hoshi M, Yagihara S
Biological Science Laboratories, Kao Corporation, 2606, Akabane, Ichikai, Haga, Tochigi 321-34, Japan.
Biochim Biophys Acta. 1998 Aug 24;1381(3):293-304. doi: 10.1016/s0304-4165(98)00041-5.
The dielectric properties of the human skin stratum corneum (SC) in the frequency range higher than 107 Hz are not well understood because of the difficulty in selective scanning of the SC area in vivo. The present study was carried out to make clear factors responsible for the dielectric properties using a measuring system specially developed for the study of SC [S. Naito, M. Hoshi, S. Mashimo, Anal. Biochem. 251 (1997) 163-172]. We found that the dielectric properties of SC can be expressed by the linear combination of two relaxation processes and d.c. conduction. The faster relaxation is that of free water. The slower relaxation and d. c. conduction were analyzed using a model assuming interfacial polarization between dissimilar materials. We concluded that the polarization is the origin of the slower relaxation process because the experimental data could be well interpreted according to the above mechanism. We also concluded that the polarization of swelled SC locates at the interface between SC cells and the intercellular lipid layer, or at the interface between the lipophilic and the hydrophilic part of the lamellar structured intercellular lipid layer.
由于在体内对角质层（SC）区域进行选择性扫描存在困难，人们对频率高于107 Hz范围内人体皮肤角质层的介电特性了解不足。本研究使用专门为角质层研究开发的测量系统进行，以明确影响介电特性的因素[S. Naito, M. Hoshi, S. Mashimo, Anal. Biochem. 251 (1997) 163 - 172]。我们发现，角质层的介电特性可以通过两个弛豫过程和直流传导的线性组合来表示。较快的弛豫是自由水的弛豫。使用一个假设不同材料间界面极化的模型分析了较慢的弛豫和直流传导。我们得出结论，极化是较慢弛豫过程的起源，因为根据上述机制实验数据能够得到很好的解释。我们还得出结论，肿胀角质层的极化位于角质形成细胞与细胞间脂质层之间的界面，或者位于层状结构细胞间脂质层的亲脂部分与亲水部分之间的界面。
