Hui C S, Chandler W K
Department of Physiology, Indiana University School of Medicine, Indianapolis 46223.
J Gen Physiol. 1990 Aug;96(2):257-97. doi: 10.1085/jgp.96.2.257.
Intramembranous charge movement was measured in cut twitch fibers mounted in a double Vaseline-gap chamber with either a tetraethylammonium chloride (TEA.Cl) or a TEA2.SO4 solution (13-14 degrees C) in the central pool. Charge vs. voltage data were fitted by a single two-state Boltzmann distribution function. The average values of V (the voltage at which steady-state charge is equally distributed between the two Boltzmann states), k (the voltage dependence factor), and qmax/cm (the maximum charge divided by the linear capacitance, both per unit length of fiber) were V = -53.3 mV (SEM, 1.1 mV), k = 6.3 mV (SEM, 0.3 mV), qmax/cm = 18.0 nC/microF (SEM, 1.1 nC/microF) in the TEA.Cl solution; and V = -35.1 mV (SEM, 1.8 mV), k = 10.5 mV (SEM, 0.9 mV), qmax/cm = 36.3 nC/microF (SEM, 3.2 nC/microF) in the TEA2.SO4 solution. These values of k are smaller than those previously reported for cut twitch fibers and are as small as those reported for intact fibers. If a correction is made for the contributions of currents from under the Vaseline seals, V = -51.2 mV (SEM, 1.1 mV), k = 7.2 mV (SEM, 0.4 mV), qmax/cm = 22.9 nC/microF (SEM, 1.4 nC/microF) in the TEA.Cl solution; and V = -34.0 mV (SEM, 1.9 mV), k = 10.1 mV (SEM, 1.1 mV), qmax/cm = 38.8 nC/microF (SEM, 3.2 nC/microF) in the TEA2.SO4 solution. With this correction, however, the fit of the theoretical curve to the data is poor. A good fit with this correction can be obtained with a sum of two Boltzmann distribution functions. The first has average values V = -33.0 mV (SEM, 2.8 mV), k = 11.0 mV (SEM, 0.5 mV), qmax/cm = 10.6 nC/microF (SEM, 1.0 nC/microF) in the TEA.Cl solution; and V = -20.0 mV (SEM, 3.3 mV), k = 17.0 mV (SEM, 2.0 mV), qmax/cm = 36.4 nC/microF (SEM, 2.3 nC/microF) in the TEA2.SO4 solution. The second has average values V = -56.5 mV (SEM, 1.3 mV), k = 2.9 mV (SEM, 0.4 mV), qmax/cm = 13.2 nC/microF (SEM, 1.0 nC/microF) in the TEA.Cl solution; and V = -41.6 mV (SEM, 1.4 mV), k = 2.5 mV (SEM, 0.8 mV), qmax/cm = 11.8 nC/microF (SEM, 1.7 nC/microF) in the TEA2.SO4 solution. When a fiber is depolarized to near V of the second Boltzmann function, a slowly developing "hump" appears in the ON-segment of the current record.(ABSTRACT TRUNCATED AT 400 WORDS)
在置于双凡士林间隙室中的切断的单收缩纤维中测量膜内电荷移动，中央池中装有四乙铵氯化物（TEA.Cl）或硫酸二乙铵（TEA2.SO4）溶液（13 - 14摄氏度）。电荷与电压数据通过单一的双态玻尔兹曼分布函数拟合。在TEA.Cl溶液中，V（稳态电荷在两个玻尔兹曼态之间均匀分布时的电压）、k（电压依赖性因子）和qmax/cm（最大电荷除以线性电容，均为每单位纤维长度）的平均值分别为V = -53.3 mV（标准误，1.1 mV），k = 6.3 mV（标准误，0.3 mV），qmax/cm = 18.0 nC/μF（标准误，1.1 nC/μF）；在TEA2.SO4溶液中，V = -35.1 mV（标准误，1.8 mV），k = 10.5 mV（标准误，0.9 mV），qmax/cm = 36.3 nC/μF（标准误，3.2 nC/μF）。这些k值小于先前报道的切断单收缩纤维的值，并且与完整纤维报道的值一样小。如果对凡士林密封下电流的贡献进行校正，在TEA.Cl溶液中，V = -51.2 mV（标准误，1.1 mV），k = 7.2 mV（标准误，0.4 mV），qmax/cm = 22.9 nC/μF（标准误，1.4 nC/μF）；在TEA2.SO4溶液中，V = -34.0 mV（标准误，1.9 mV），k = 10.1 mV（标准误，1.1 mV），qmax/cm = 38.8 nC/μF（标准误，3.2 nC/μF）。然而，进行此校正后，理论曲线与数据的拟合较差。使用两个玻尔兹曼分布函数的和可以得到此校正后的良好拟合。第一个在TEA.Cl溶液中的平均值为V = -33.0 mV（标准误，2.8 mV），k = 11.0 mV（标准误，0.5 mV），qmax/cm = 10.6 nC/μF（标准误，1.0 nC/μF）；在TEA2.SO4溶液中，V = -20.0 mV（标准误，3.3 mV），k = 17.0 mV（标准误，2.0 mV），qmax/cm = 36.4 nC/μF（标准误，2.3 nC/μF）。第二个在TEA.Cl溶液中的平均值为V = -56.5 mV（标准误，1.3 mV），k = 2.9 mV（标准误，0.4 mV），qmax/cm = 13.2 nC/μF（标准误，1.0 nC/μF）；在TEA2.SO4溶液中，V = -41.6 mV（标准误，1.4 mV），k = 2.5 mV（标准误，0.8 mV），qmax/cm = 11.8 nC/μF（标准误，1.7 nC/μF）。当纤维去极化到第二个玻尔兹曼函数附近的V时，电流记录的开启段会出现一个缓慢发展的“驼峰”.（摘要截断于400字）
