大鼠破骨细胞膜内向整流的两种钾离子电流类型：单通道分析

Kai Y, Ikemoto Y, Abe K, Oka M

Second Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Kyushu University, Fukuoka, Japan.

Jpn J Physiol. 1996 Jun;46(3):231-41. doi: 10.2170/jjphysiol.46.231.

Electrical membrane properties of spread type-osteoclasts were examined using the whole-cell and cell-attached configurations of the patch clamp technique. The membrane potential of the osteoclasts was measured and grouped into two populations: hyperpolarized and depolarized (around -80 and 0 mV, respectively). The current-voltage relation was N-shaped, showing the property of inward rectification which was produced by K+ conductance. Either Na+ or Ca2+ inward currents were not observed. 2) The single-channel recordings were made with osteoclasts of the hyperpolarized population. Two types (slow and fast) of the current were analyzed, which appeared predominantly and had large unit conductances. The reversal potential for both types shifted according to the equilibrium potential for K+. 3) The slow type had high open probabilities (> or = 0.85) at all potentials examined. The mean open time was 349 ms at the resting potential (RP) and had a tendency to become shorter with hyperpolarization of the membrane. The closed time histogram was fitted with a double exponential function, yielding closed times of 8.3 and 55.2 ms at RP, which were not changed by hyperpolarization. The unit conductance was 32.0 pS. No outward currents were recorded at depolarized potentials to RP. 4) The open probability of the fast type was 0.25 at RP and increased with hyperpolarization of the membrane (0.55 at -80 mV to RP). The mean open time was short (2.6 ms at RP), which became longer with hyperpolarization. The channel had two closed times, 2.8 and 15.3 ms at RP, which were not voltage dependent. The unit conductance was 38.8 pS in the range of hyperpolarization from RP. The amplitude of outward currents evoked by voltage pulses beyond RP was small, probably due to rapid flickering of the current. 5) The two types of single-channel K+ currents showed the inwardly rectifying property and may play an important role in the inward rectification seen in the whole-cell configuration.

使用膜片钳技术的全细胞和细胞贴附模式，检测了铺展型破骨细胞的电膜特性。测量了破骨细胞的膜电位，并将其分为两个群体：超极化和去极化群体（分别约为 -80 mV 和 0 mV）。电流 - 电压关系呈 N 形，显示出由 K⁺ 电导产生的内向整流特性。未观察到 Na⁺ 或 Ca²⁺ 内向电流。2) 对超极化群体的破骨细胞进行了单通道记录。分析了两种类型（慢型和快型）的电流，它们占主导且具有较大的单位电导。两种类型的反转电位均根据 K⁺ 的平衡电位而变化。3) 慢型在所有检测电位下都具有较高的开放概率（≥0.85）。在静息电位（RP）时平均开放时间为 349 ms，并且随着膜的超极化有缩短的趋势。关闭时间直方图拟合为双指数函数，在 RP 时产生的关闭时间为 8.3 ms 和 55.2 ms，超极化时不变。单位电导为 32.0 pS。在去极化至 RP 的电位下未记录到外向电流。4) 快型在 RP 时的开放概率为 0.25，并随着膜的超极化而增加（在相对于 RP 为 -80 mV 时为 0.55）。平均开放时间较短（在 RP 时为 2.6 ms），随着超极化而变长。该通道在 RP 时有两个关闭时间，分别为 2.8 ms 和 15.3 ms，与电压无关。在相对于 RP 的超极化范围内，单位电导为 38.8 pS。超过 RP 的电压脉冲诱发的外向电流幅度较小，可能是由于电流的快速闪烁。5) 两种类型的单通道 K⁺ 电流表现出内向整流特性，可能在全细胞模式下观察到的内向整流中起重要作用。