Erdemli G, Krnjević K
Anaesthesia Research Department, McGill University, Montréal, PQ, Canada.
Neuroreport. 1994 Jun 27;5(11):1362-4.
Voltage-dependent outward currents were examined in CA1 neurones by whole-cell recording in slices. Nine cells were recorded with the 'standard' internal solution (KMeSO4, HEPES, EGTA, CaCl2, and MgCl2) and held a potential (-54 +/- 3 mV) at which there was no significant outward current. Cromakalim (CROM, 100 microM) reduced both input conductance (GN) (by 14 +/- 4%) and outward currents, evoked over a wide range of potentials by brief depolarizing pulses: at -4.0 +/- 3.0 mV, currents diminished by 30 +/- 10%. When 1 mM GDP was added to the standard internal solution, there was a significant outward current at approximately -54 mV; and CROM greatly increased outward currents near -4.0 mV (by 99 +/- 26.4%, n = 10). The enhanced outward currents were reduced by CROM washout (in two cells) and by 10 microM glyburide (GLYB, in four cells). When six other cells were recorded with electrodes containing both ATP (5 mM) and GDP (1 mM), there was no net outward current at approximately -54 mV and CROM reduced outward currents (at approximately 0 mV, by 37.5 +/- 10.9%). We conclude that GDP in hippocampal neurones appears to activate an ATP- and GLYB-sensitive outward current, which is much potentiated by CROM.
通过切片中的全细胞记录法研究了CA1神经元中电压依赖性外向电流。用“标准”细胞内溶液（硫酸钾、羟乙基哌嗪乙磺酸、乙二醇双乙醚二胺四乙酸、氯化钙和氯化镁）记录了9个细胞，并将膜电位保持在（-54±3 mV），此时没有明显的外向电流。克罗卡林（CROM，100微摩尔）降低了输入电导（GN）（降低了14±4%）以及外向电流，短暂去极化脉冲在很宽的电位范围内诱发外向电流：在-4.0±3.0 mV时，电流减少了30±10%。当向标准细胞内溶液中加入1毫摩尔鸟苷二磷酸（GDP）时，在约-54 mV处出现明显的外向电流；并且CROM在-4.0 mV附近极大地增加了外向电流（增加了99±26.4%，n = 10）。通过冲洗CROM（在两个细胞中）和10微摩尔格列本脲（GLYB，在四个细胞中）可使增强的外向电流降低。当用含有三磷酸腺苷（ATP，5毫摩尔）和GDP（1毫摩尔）的电极记录另外6个细胞时，在约-54 mV处没有净外向电流，并且CROM降低了外向电流（在约0 mV处，降低了37.5±10.9%）。我们得出结论，海马神经元中的GDP似乎激活了一种对ATP和GLYB敏感的外向电流，该电流被CROM极大地增强。
