Matteson D R, Armstrong C M
J Gen Physiol. 1984 Mar;83(3):371-94. doi: 10.1085/jgp.83.3.371.
The ionic conductances of GH3 cells, a transformed line from rat anterior pituitary, have been studied using the whole-cell variant of the patch-clamp technique (Hamill et al., 1981). Pipettes of very low resistance were used, which improved time resolution and made it possible to control the ion content of the cell interior, which equilibrated very rapidly with the pipette contents. Time resolution was further improved by using series resistance compensation and "ballistic charging" of the cell capacitance. We have identified and partially characterized at least three conductances, one carrying only outward current, and the other two normally inward. The outward current is absent when the pipette is filled with Cs+ instead of K+, and has the characteristics of a voltage-dependent potassium conductance. One of the two inward conductances (studied with Cs+ inside) has fast activation, inactivation and deactivation kinetics, is blocked by tetrodotoxin (TTX), and has a reversal potential at the sodium equilibrium potential. The other inward current activates more slowly and deactivates with a quick phase and a very slow phase after a short pulse. Either Ca++ or Ba++ serves as current carrier. During a prolonged pulse, current inactivates fairly completely if there is at least 5 mM Ca++ outside, and the amplitude of the current tails following the pulse diminishes with the time course of inactivation. When Ba++ entirely replaces Ca++ in the external medium, there is no inactivation, but deactivation kinetics of Ca channels vary as pulse duration increases: the slow phase disappears, the fast phase grows in amplitude. Inactivation (Ca++ outside) is unaltered by 50 mM EGTA in the pipette: inactivation cannot be the result of internal accumulation of Ca++.
利用膜片钳技术的全细胞变体（Hamill等人，1981年），对来自大鼠垂体前叶的转化细胞系GH3细胞的离子电导进行了研究。使用了极低电阻的微电极，这提高了时间分辨率，并使得控制细胞内的离子含量成为可能，细胞内的离子含量能与微电极内的溶液迅速达到平衡。通过使用串联电阻补偿和对细胞电容进行“弹道充电”，时间分辨率得到了进一步提高。我们已经识别并部分表征了至少三种电导，一种仅携带外向电流，另外两种通常为内向电流。当微电极中充满Cs⁺而不是K⁺时，外向电流消失，并且具有电压依赖性钾电导的特征。两种内向电导之一（在细胞内充Cs⁺时进行研究）具有快速激活、失活和去激活动力学，被河豚毒素（TTX）阻断，并且在钠平衡电位处具有反转电位。另一种内向电流激活较慢，在短脉冲后以快速相和非常缓慢的相去激活。Ca²⁺或Ba²⁺均可作为电流载体。在长时间脉冲期间，如果细胞外至少有5 mM Ca²⁺，电流会相当完全地失活，并且脉冲后的电流尾波幅度会随着失活的时间进程而减小。当Ba²⁺完全替代细胞外介质中的Ca²⁺时，没有失活现象，但Ca通道的去激活动力学随脉冲持续时间的增加而变化：缓慢相消失，快速相幅度增大。微电极中50 mM EGTA不会改变（细胞外有Ca²⁺时的）失活现象：失活不可能是细胞内Ca²⁺积累的结果。
