Characterization of a delayed rectifier potassium current in chicken growth plate chondrocytes.
Characterization of a delayed rectifier potassium current in chicken growth plate chondrocytes.
复制标题
鸡生长板软骨细胞延迟整流钾电流的表征。
DOI：
10.1152/ajpcell.1992.262.5.c1335
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Wuthier,RE
中科院分区：
文献类型：
--
作者：
Walsh,KB;Cannon,SD;Wuthier,RE
利用膜片钳技术的全细胞排列，在培养的鸡生长板软骨细胞中发现了一个向外的时间依赖性钾电流。这种延迟整流器钾电流（IK）在电压阶跃到正电位至-40 mV期间以s型时间过程激活。电流激活所需的半最大电压确定为-8 mV。使用失活尾电流测量IK的逆转电位（Erev），在140 mM的内部和5 mM的外部[K+]溶液存在下为-72 mV。外部[K+]的变化导致Erev以钾选择通道的方式移动。此外，外部[K+]从5 mM增加到50 mM，尾电流的斜率电导增加了两倍。0.5 ~ 4mm浓度的钾通道阻滞剂4-氨基吡啶（4-AP）和10 nM浓度的蝎毒毒毒素（CTX; 10 nM）对软骨细胞IK有抑制作用，但10 mM四乙基铵（TEA）对IK无影响。添加20微米的ZnCl2以电压依赖的方式降低IK，在接近电流激活阈值的电位处发现最大的抑制作用。ZnCl2对IK的还原伴随着IK激活动力学的减慢。基于该电流的门控和药理学特性，提示软骨细胞通道属于骨和免疫系统细胞中发现的K+通道超家族。软骨细胞K+通道可能导致生长板软骨细胞外液中异常高的[K+]。
With the use of the whole cell arrangement of the patch-clamp technique, an outward-directed time-dependent potassium current was identified in cultured chicken growth plate chondrocytes. This delayed rectifier potassium current (IK) activated with a sigmoidal time course during voltage steps to potentials positive to -40 mV. The half-maximal voltage required for current activation was determined to be -8 mV. The reversal potential (Erev) for IK, measured using deactivating tail currents, was -72 mV in the presence of 140 mM internal and 5 mM external [K+] solutions. Changes in external [K+] caused Erev to shift in a manner expected for a potassium-selective channel. In addition, increasing external [K+] from 5 to 50 mM caused the slope conductance of the tail currents to increase twofold. The chondrocyte IK was inhibited by the potassium-channel blocker 4-aminopyridine (4-AP) at concentrations of 0.5-4 mM and by the scorpion venom toxin charybdotoxin (CTX; 10 nM) but was unaffected by 10 mM tetraethylammonium (TEA). Addition of 20 microM ZnCl2 reduced IK in a voltage-dependent manner with the greatest inhibition found to occur at potentials near the threshold for current activation. Reduction of IK by ZnCl2 was accompanied by a slowing in the kinetics of IK activation. On the basis of the gating and pharmacological properties of this current, it is suggested that the chondrocyte channel belongs to a superfamily of K+ channels found in bone and immune system cells. The chondrocyte K+ channel may contribute to the unusually high [K+] found in the extracellular fluid of growth plate cartilage.