铅对大鼠海马神经元钠电流的抑制作用

目的　铅对神经系统有损害作用 ,钠通道是神经元产生和传递电信号的重要枢纽 ,故研究铅对大鼠海马CA1区神经元钠电流 (INa)的影响。方法全细胞膜片钳技术。结果　醋酸铅可浓度依赖地抑制INa,1 ,1 0 ,50和 1 0 0 μmol·L-1 醋酸铅对INa的抑制率分别为 (8.2± 0 .8) % ,(2 0 .9± 2 .6) % ,(51 .8±4.8) %和 (66 .4±5 .7) %。此外 ,它还与电压呈依赖关系 ,50 μmol·L-1 醋酸铅可使INa的激活曲线显著右移 ,但不改变斜率因子 ,还可使INa的失活曲线显著左移。结论　铅可抑制INa的激活过程 ,可促进INa的失活过程。铅改变了细胞膜的电压感应 ,这可能是铅损伤海马神经元的作用机制之一

Inhibitory effect of lead on sodium currents in acutely isolated rat hippocampal neurons

AIM Lead injures nerve system. Because sodium channels are pivotal in generation and conduction of electrical signals in neurons, the effect of lead on sodium current (I_Na) in freshly dissociated hippocampal neurons of rats was studied. METHODS The whole-cell patch clamp techniques were used. RESULTS The results showed that 1, 10, 50, 100 μmol•L^-1 Pb(Ac)₂ inhibited the amplitude of I_Na by（8.2±0.8）%,（20.9±2.6）%,(51.8±4.8)% and （66.4±5.7）%（n=10）, respectively. It suggested that the inhibition of Pb(Ac)₂ on INa be concentration-dependent. The inhibition of Pb(Ac)₂ on INa was also voltage-dependent. The activation curve of I_Na was shifted to right and the inactivation curve was shifted to left with 50 μmol•L^-1 Pb(Ac)₂. CONCLUSION The inhibition of lead on I_Na significantly increases the excitation of hippocampal neurons, which may take an assistant part in lead neurotoxication.