Both barium and calcium activate neuronal potassium currents.
Both barium and calcium activate neuronal potassium currents.
复制标题
钡和钙都会激活神经元钾电流。
DOI：
10.1073/pnas.84.18.6577
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发表时间：
1987
影响因子：
11.1
通讯作者：
Spitzer,NC
中科院分区：
文献类型：
--
作者：
Ribera,AB;Spitzer,NC
培养的两栖类脊髓神经元具有快速失活和持续的钙依赖性钾电流成分，类似于其他细胞的描述。二价阳离子依赖性的全细胞外向电流通过从不含镉但存在渗透性二价阳离子（50-100 μ M）的电流中减去在不渗透性镉（100-500 μ M）存在下非洲爪蟾神经元记录的电压依赖性钾电流来分离。这些渗透离子的浓度足够低，以避免通过钙通道的宏观内向电流的污染。钙依赖性钾电流被1 μ M四乙基铵降低。这些电流也可以被钡或锶激活。钡以及钙激活外向电流在年轻的神经元（6-8小时）和相对成熟的神经元（19-26小时在体外）。然而，钡内流似乎抑制了大多数细胞的持续电压依赖性钾电流。钡还激活至少一类钾通道观察切除膜补丁，而阻止其他。在其他系统中，这种阻断作用可能掩盖和阻碍了对钡刺激作用的检测。
Amphibian spinal neurons in culture possess both rapidly inactivating and sustained calcium-dependent potassium current components, similar to those described for other cells. Divalent cation-dependent whole-cell outward currents were isolated by subtracting the voltage-dependent potassium currents recorded from Xenopus laevis neurons in the presence of impermeant cadmium (100-500 microM) from the currents produced without cadmium but in the presence of permeant divalent cations (50-100 microM). These concentrations of permeant ions were low enough to avoid contamination by macroscopic inward currents through calcium channels. Calcium-dependent potassium currents were reduced by 1 microM tetraethylammonium. These currents can also be activated by barium or strontium. Barium as well as calcium activated outward currents in young neurons (6-8 hr) and in relatively mature neurons (19-26 hr in vitro). However, barium influx appeared to suppress the sustained voltage-dependent potassium current in most cells. Barium also activated at least one class of potassium channels observed in excised membrane patches, while blocking others. The blocking action may have masked and hindered detection of the stimulatory action of barium in other systems.