活性氧对大鼠肝卵圆细胞株WB-F344钾通道的作用

EFFECTS OF OXYGEN FREE RADICALS ON K^+ CHANNELS IN WB-F344 CELLS

用膜片箝技术的细胞贴附式 (cell-attached)观察O2.-对大鼠肝卵圆细胞株WB -F344K +通道活动的影响 ,结果发现 :1)在细胞处于静息状态时 ,在箝制电压为0mV ,每10mV阶跃 ,测试电压分别达±120mV范围内未记录到通道活动。此时 ,小剂量O2.- 也不能激活WB细胞的通道活动。在细胞外液中加入20mmol/LCaCl2 后通道开启 ,记录到小振幅的通道活动 ,它们的电导是9.48±0.93ps(n=4)。此时再用O2.-作用于细胞 ,通道被激活 ,通道电导增大 ,在正测试电压时为15.74±5.46ps(n=8) ,在负测试电压时为48.32±8.67ps(n=6)。通道活动具有外向整流特性。2)胞外加入4 -AP可抑制该通道的活动 ,而SNP则可增强通道的活动。

Oxidant-induced damage has been implicated in the pathogenesis of several forms of cellular injury. In the present study cell-attached clamp technique was employed to determine if oxidant stress leads to activation of plasma membrane K+-channels in rat liver oval cell strain WB-F344. We found that, 1) Under experimental conditions (bath: Krebs, Pipette: High K+), if WB cells were stimulated directly by O2.- generated by interaction of Xanthine with Xanthine Oxidose (X:100μmol/L, XO:0.1mu/ml), channel activity was found. However, if 20mmol/L CaCl2 were exposed to cell bath, a small amplitude channel activity was recorded with the channel conductance 9.48±0.93ps(n=4). If CaCl2 and O2.- were exposed to cell bath, large amplitude channel activity was shown. In positive testing potential voltage, the activated channel conductance was 15.74±5.46ps(n=8); In negative testing potential voltage, the channel conductance was 48.32±8.67ps(n=6). 2) In ion replacement experiments these channels appeared as potassium channels. Potassium channels blocker 4-AP (2mmol/L) inhibited the currents and SNP (10nmol/L) increased the currents. These result suggests that activation of K+-channels seems to be important for the signal transduction of cellular responses to oxidant stress.