THERMOELECTRICAL ANALYSIS OF THE HUMAN SKIN BARRIER
THERMOELECTRICAL ANALYSIS OF THE HUMAN SKIN BARRIER
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DOI：
10.1016/0040-6031(94)01887-m
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发表时间：
1995-01-02
影响因子：
3.5
通讯作者：
BODDE, HE
中科院分区：
文献类型：
--
作者：
CRAANEVANHINSBERG, WHM;VERHOEF, JC;BODDE, HE
研究了温度对体外人角质层的电阻和电容特性的影响，以确定角质层的亚结构内电阻R和电容C分量的位置。加热-冷却循环根据人角质层脂质和/或蛋白质的热转变的早期量热和光谱研究来设计。使用了两种不同的方案。(A)在pH 7.4磷酸盐缓冲盐水中同时进行热处理和电分析，从pH 7.4的预水合角质层（70%w/w）开始。(B)在电分析之前，使用干燥的角质层（<10%w/w）进行热处理，然后进行预水合并在20 ℃的磷酸盐缓冲盐水中测量电特性。每60秒施加13 μ A cm-2的方波交流脉冲。对所得到的角质层上的电压波形的分析产生了角质层的等效电模型，该等效电模型由两个RC电路（R1与C1并联，R2与C2并联）的串联连接组成。低于60 ℃时，测得的恒定活化能为5.4 +/- 0.7 kcal mol-1，这接近于K+在流体水性介质中扩散的活化能。角质层的总电阻小于100 k Ω cm 2，这与黑色脂质膜的电阻（1-10 k Ω cm 2）相比非常低。人角质层的低活化能和电阻都表明存在通过膜的高导电通路。在60 ℃和75 ℃之间，观察到电阻R1和R2的突然下降以及电容C1和C2的快速上升。该温度间隔对应于在人角质层中观察到的第二热转变的温度间隔，该第二热转变是脂质相变。超过75摄氏度，电阻相当恒定，而电容继续增加。加热到75 ℃和95 ℃所引起的电阻和电容的变化是完全不可逆的。这与X射线衍射研究一致，
The influence of temperature on the resistive and capacitative properties of human stratum corneum in vitro was studied to determine where within substructures of stratum corneum, the electrical resistance R and capacitance C components reside. Heating-cooling cycles were designed in accordance with earlier calorimetric and spectroscopic studies of thermal transitions of human stratum corneum lipids and/or proteins. Two different protocols were used. (A) Heat treatment and electrical analysis were carried out simultaneously in pH 7.4 phosphate buffered saline, starting with prehydrated stratum corneum (70% w/w) of pH 7.4. (B) Heat treatment was performed before electrical analysis, using dried stratum corneum (< 10% w/w), followed by prehydration and measurement of the electrical properties in phosphate buffered saline at 20-degrees-C. Square-wave alternating current pulses of 13 muA cm-2 were applied every 60 s. Analysis of the resulting voltage waveform across stratum corneum yielded an equivalent electrical model of stratum corneum composed of a series connection of two RC circuits (R1 parallel-to C1 and R2 parallel-to C2). Below 60-degrees-C a constant activation energy of 5.4 +/- 0.7 kcal mol-1 was measured, which was close to the activation energy of K+ diffusion in a fluid aqueous medium. The total resistance of stratum corneum was less than 100 kOMEGA cm2, which is very low compared to the resistance of black lipid membranes (1-10 MOMEGA cm2). Both the low activation energy and resistance of human stratum corneum suggest the presence of highly conductive pathways through the membrane. Between 60 and 75-degrees-C an abrupt decline of the resistances R1 and R2 and a rapid rise of the capacitances C1 and C2 was observed. This temperature interval corresponded to the temperature interval of the second thermal transition observed in human stratum corneum, which is a lipid phase transition. Beyond 75-degrees-C, the resistances were fairly constant, while the capacitances continued to increase. The changes in the resistances and capacitances brought about by heating to 75 and 95-degrees-C were completely irreversible. This is in agreement with X-ray diffraction studies, which