过氧化氢对培养大鼠海马神经元瞬时外向钾电流的影响

目的　研究过氧化氢对海马神经元上瞬时外向钾电流的影响。方法　采用全细胞膜片钳技术记录培养大鼠海马神经元瞬时外向钾电流的变化。结果　 3 0 μmol·L-1H2 O2 孵育 12h后 (1)明显抑制IA,电流密度由 (5 3 8±15 8) pA·pF-1变为 (18 5± 6 2 ) pA·pF-1(n =10 ,P <0 0 1) ;(2 )明显抑制IA 激活作用 ,半数最大激活电压由 (-15 2± 3 6)mV左移至 (- 18 2± 2 7)mV(n =10 ,P <0 0 1) ;(3 )明显抑制IA 失活作用 ,失活常数由 (42 2± 10 1)ms变为 (81 9± 3 5 0 )ms(n =10 ,P <0 0 5 ) ,半数最大灭活膜电位V1/ 2 由 (- 87 5± 12 6)mV变为 (- 99 8± 2 1)mV(n =10 ,P <0 0 1) ;(4)明显抑制IA 电流失活后复活作用 ;恢复时间常数由 (2 7 9± 14 1)ms变为 (5 8 6± 10 0 )ms(n=10～ 11,P <0 0 1) ;(5 )降低静息膜电位 ,由 (- 64 9±9 4)mV变为 (- 46 0± 12 8)mV(n =6～ 11,P <0 0 1) ,延长动作电位时程 ,由 (8 7± 3 4)ms增至 (16 0± 6 2 )ms(n =6～ 11,P <0 0 5 )。结论　H2 O2 对IA 的抑制作用可能参与其对神经元的氧化应激损伤毒性

Effect of H2O2 on transient outword potassium current in the cultured rat hippocampal neurons

AIM To study the effects of H 2O 2 on transient outward potassium current METHODS Whole cell patch clamp technique was used to record changes of I A in the cultured rat hippocampal neurons RESULTS After exposure to 30 μmol·L -1 H 2O 2 for 12 h (1) decreased I A current density from (53 8±15 8) PA·PF -1 to (18 5±6 2) PA·PF -1 ( n=10,P< 0 01);(2) inhibited I A activation, half maxi activation voltage from (-15 2±3 6) mV to (-18 2±2 7) mV( n=10, P< 0 01); (3) inhibited I A inactivation, inactivation time constant from (42 2±10 1) ms to (81 9±35 0) ms( n=10,P< 0 05),half maxi inactivation voltage from (-87 5±12 6) mV to (-99 8±2 1) mV ( n=10, P< 0 01); (4) inhibited I A recovery from inactivation, recovery time constant (τ) from(27 9±14 1) ms to (58 6±10 0) ms( n=10～11,P< 0 01); (5)decreased resting membrane potential(RMP) from (-64 9±9 4) mV to (-46 0±12 8) mV( n=6～11, P< 0 01),increased APD 95 from (8 7±3 4) ms to (16 0±6 2) ms ( n=6～11, P< 0 05) CONCLUSION Inhibitory effect of H 2O 2 on I A may be involved in its oxidative stress injury