Hill P B, Martin R J, Miller H R
Department of Preclinical Veterinary Sciences, Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Summerhall, Edinburgh, EH9 1QH, Scotland, UK.
Pflugers Arch. 1996 Oct;432(6):986-94. doi: 10.1007/s004240050226.
Rat mucosal type mast cells are thought to possess only a K+-selective inwardly rectifying (IRK) current in the resting state. We used rat-bone-marrow-derived mast cells (BMMCs) as a model of mucosal mast cells and recorded whole-cell membrane currents from cells perforated with amphotericin B. Under these conditions, both inwardly rectifying (IR) and outwardly rectifying (OR) currents were observed. The reversal potential and conductance of the IR current depended on the extracellular K+ concentration, indicating that the channel was K+ selective. The OR current was not affected by changes in extracellular K+ concentration, but lowering extracellular Cl- concentration reduced the conductance and shifted the reversal potential in a positive direction. The OR current was not affected by K+ channel blockers, but was reversibly blocked by the chloride channel blocker 4,4'-diisothiocyanato-2,2'-stilbenedisulphonate (DIDS), again indicating a Cl- conductance. The IRK current was also detected in the majority of cells using the conventional whole-cell recording configuration at room temperature. In contrast, the ORCl current was only observed in 7% of recordings made at room temperature with the conventional whole-cell voltage-clamp mode, but was detected in 66% of cells if the bath temperature was increased and the integrity of the cell's cytoplasm was preserved by using the perforated-patch technique. Under similar conditions, the ORCl current was also present in rat peritoneal mast cells, a connective tissue phenotype previously thought to have no whole-cell currents in the resting state. The role of this current and factors affecting its activation are discussed.
大鼠黏膜型肥大细胞被认为在静息状态下仅具有一种K⁺选择性内向整流（IRK）电流。我们使用大鼠骨髓来源的肥大细胞（BMMCs）作为黏膜肥大细胞的模型，并记录了用两性霉素B穿孔的细胞的全细胞膜电流。在这些条件下，观察到了内向整流（IR）电流和外向整流（OR）电流。IR电流的反转电位和电导取决于细胞外K⁺浓度，表明该通道具有K⁺选择性。OR电流不受细胞外K⁺浓度变化的影响，但降低细胞外Cl⁻浓度会降低电导并使反转电位向正向移动。OR电流不受K⁺通道阻滞剂的影响，但可被氯离子通道阻滞剂4,4'-二异硫氰酸-2,2'-二苯乙烯二磺酸（DIDS）可逆性阻断，再次表明存在Cl⁻电导。在室温下使用传统的全细胞记录配置时，大多数细胞中也检测到了IRK电流。相比之下，在室温下使用传统的全细胞电压钳模式进行的记录中，仅在7%的记录中观察到了ORCl电流，但如果提高浴温并使用穿孔膜片技术保持细胞胞质的完整性，则在66%的细胞中检测到了该电流。在类似条件下，大鼠腹膜肥大细胞中也存在ORCl电流，腹膜肥大细胞是一种结缔组织表型，以前认为在静息状态下没有全细胞电流。本文讨论了该电流的作用及其激活的影响因素。
