Zucker R S, Smith S J
Brain Res. 1979 Jun 15;169(1):91-102. doi: 10.1016/0006-8993(79)90376-7.
Aplysia central neurons were injected with the calcium-sensitive photoprotein aequorin and stimulated with trains of identical depolarizing voltage-clamp pulses. The light emissions grew and the outward currents declined in successive pulses. Tetraethylammonium (TEA) enhanced the light emissions to single depolarizing pulses and suppressed the outward current. The remaining net inward current is carried primarily by calcium ions and does not facilitate. The aequorin emissions were larger at all amplitudes of depolarizing pulses that elicited emissions, and the facilitation of emissions in a train of pulses was reduced. The effect of TEA on outward current was nearly maximal when sodium ions were partially replaced with 0.1 M TEA, while the aequorin emissions were further enhanced by increasing the TEA concentration to 0.459 M. TEA enhanced the aequorin emissions at all voltages. These observations suggest that the action of TEA on aequorin emissions is not strictly a consequence of its better known outward current blocking action. The effects of TEA could be partly due to the lowered sodium concentration of these solutions. Replacement of sodium by Tris, sucrose or mannose, however, all produced no enhancement of emissions. Tetramethylammonium (TMA) replacement of sodium had effects similar to those of TEA. Thus TEA and TMA appear to have a specific effect. Part of the enhancement of light emissions by TEA is due to the removal of a series resistance error in the voltage clamp, and this may also account partly for the reduced facilitation of aequorin emissions in TEA. The remainder of the action of TEA on aequorin emissions evidently reflects a specific but previously unrecognized action on the cellular metabolism of calcium ions or on the voltage-dependent calcium channels.
将钙敏感光蛋白水母发光蛋白注入海兔中枢神经元，并使用一系列相同的去极化电压钳脉冲进行刺激。在连续的脉冲中，光发射增强，外向电流下降。四乙铵（TEA）增强了单个去极化脉冲的光发射，并抑制了外向电流。剩余的内向净电流主要由钙离子携带，且不具有易化作用。在所有引发光发射的去极化脉冲幅度下，水母发光蛋白的发射都更大，并且一串脉冲中光发射的易化作用减弱。当用0.1 M TEA部分替代钠离子时，TEA对外向电流的作用几乎达到最大值，而将TEA浓度增加到0.459 M时，水母发光蛋白的发射进一步增强。TEA在所有电压下都增强了水母发光蛋白的发射。这些观察结果表明，TEA对水母发光蛋白发射的作用并非严格是其更为人熟知的外向电流阻断作用的结果。TEA的作用可能部分归因于这些溶液中钠离子浓度的降低。然而，用Tris、蔗糖或甘露糖替代钠离子均未产生发射增强的效果。用四甲铵（TMA）替代钠离子产生的效果与TEA类似。因此，TEA和TMA似乎具有特定作用。TEA对光发射增强的部分原因是消除了电压钳中的串联电阻误差，这也可能部分解释了TEA中水母发光蛋白发射易化作用的降低。TEA对水母发光蛋白发射的其余作用显然反映了对钙离子细胞代谢或电压依赖性钙通道的一种特定但此前未被认识的作用。
