Cass A, Dalmark M
Acta Physiol Scand. 1979 Nov;107(3):193-203. doi: 10.1111/j.1748-1716.1979.tb06463.x.
The permeability of gramicidin-treated human red blood cell membranes to K+ and Cl- has been measured at normal ionic strength (1) by tracer exchange at steady-state distribution of salt, and (2) by net transport of salt in the presence of a salt concentration gradient. Under both conditions KCl was the only inorganic salt in cells and medium. In the studies of self-exchanges the electrical driving force on the ions was zero. Calculaton of permeability coefficients from net salt transport was simplified because the experiment was designed as a special case of the Nerst-Planck diffusion regime, i.e. the single salt case. Gramicidin altered the cell membranes from being anion to become cation selective. Gramicidin increased the potassium exchange without affecting the chloride exchange measurably. The chloride exchange showed saturation kinetics as does chloride exchange in normal cells. The net transport of KCl in the presence of a constant concentration gradient increased to a constant value with increasing gramicidin concentration. At high gramicidin concentrations (0 degree C, pH 7.2) the "chloride permeability coefficient" calculated from tracer exchange (1.9 x 10(-6) cm/s) was 290 times the chloride permeability coefficient calculated from net salt transport (0.65 x 10(-8) cm/s). The latter value corresponds to a chloride conductance of 4.2 x 10(-6) ohm-1 cm-2. The chloride permeability coefficient was 2.1 x 10(-6) cm/s at 25 degrees C (pH 6.8) indicating a value of 3 for the Q25. It appears that normal red cells are anion selective in the sense that anion permeability exceeds cation permeability with a factor of more than a hundred between 0 degrees C and body temperature. The anion exchange, i.e. the Hamburger shift, is a tightly coupled transport process which is several orders of magnitude faster than anion transport by salt diffusion.
已在正常离子强度下（1）通过盐稳态分布时的示踪剂交换，以及（2）在存在盐浓度梯度的情况下通过盐的净转运，测量了短杆菌肽处理的人红细胞膜对K⁺和Cl⁻的通透性。在这两种情况下，KCl都是细胞和培养基中唯一的无机盐。在自交换研究中，离子上的电驱动力为零。根据盐的净转运计算通透系数得以简化，因为该实验被设计为能斯特 - 普朗克扩散机制的一个特殊情况，即单盐情况。短杆菌肽使细胞膜从阴离子选择性变为阳离子选择性。短杆菌肽增加了钾交换，而对氯交换没有明显影响。氯交换表现出饱和动力学，正常细胞中的氯交换也是如此。在存在恒定浓度梯度的情况下，KCl的净转运随着短杆菌肽浓度的增加而增加到一个恒定值。在高短杆菌肽浓度下（0℃，pH 7.2），由示踪剂交换计算得到的“氯通透系数”（1.9×10⁻⁶ cm/s）是由盐净转运计算得到的氯通透系数（0.65×10⁻⁸ cm/s）的290倍。后一个值对应于4.2×10⁻⁶ ohm⁻¹ cm⁻²的氯电导。在25℃（pH 6.8）时，氯通透系数为2.1×10⁻⁶ cm/s，表明Q₂₅值为3。似乎正常红细胞在阴离子通透性超过阳离子通透性这一意义上是阴离子选择性的，在0℃至体温之间，阴离子通透性比阳离子通透性大一百多倍。阴离子交换，即汉堡转移，是一个紧密偶联的转运过程，比通过盐扩散的阴离子转运快几个数量级。
