Jackson P S, Strange K
Department of Neurosurgery, Children's Hospital, Boston, Massachusetts 02115, USA.
J Gen Physiol. 1995 May;105(5):661-76. doi: 10.1085/jgp.105.5.661.
Outwardly rectified, swelling-activated anion conductances have been described in numerous cell types. The major functional variable observed amongst these conductances is the extent and rate of depolarization-induced inactivation. In general, the conductances can be divided into two broad classes, those that show rapid inactivation in response to strong depolarization and those that show little or no voltage dependence. The swelling-activated anion conductance in rat C6 glioma cells is inactivated nearly completely by membrane depolarization above +90 mV and reactivated by membrane hyperpolarization. The kinetics of inactivation and reactivation are fit by single and double exponentials, respectively. Voltage-dependent behavior is well described by a simple linear kinetic model in which the channel exists in an open or one of three inactivated states. pH-induced changes in voltage-dependent gating suggest that the voltage sensor contains critical basic amino acid residues. Extracellular ATP blocks the channel in a voltage-dependent manner. The block is sensitive to the direction of net Cl- movement and increases open channel noise indicating that ATP interacts with the channel pore. Blockage of the channel with ATP dramatically slows depolarization-induced inactivation.
外向整流、肿胀激活的阴离子电导已在多种细胞类型中被描述。在这些电导中观察到的主要功能变量是去极化诱导失活的程度和速率。一般来说，这些电导可分为两大类，一类在强去极化时表现出快速失活，另一类则表现出很少或没有电压依赖性。大鼠C6胶质瘤细胞中的肿胀激活阴离子电导在膜去极化超过+90 mV时几乎完全失活，并通过膜超极化重新激活。失活和重新激活的动力学分别由单指数和双指数拟合。电压依赖性行为可以通过一个简单的线性动力学模型很好地描述，其中通道存在于开放状态或三种失活状态之一。pH诱导的电压依赖性门控变化表明电压传感器含有关键的碱性氨基酸残基。细胞外ATP以电压依赖性方式阻断通道。这种阻断对净Cl-移动方向敏感，并增加开放通道噪声，表明ATP与通道孔相互作用。用ATP阻断通道会显著减慢去极化诱导的失活。
