Change of Sodium Current and Its Ion Channels Mechanism After Spinal Nerve Injury

Objective:To detect the changes of sodium influx in the transected spinal nerve rats and to investigate the expression of the sodium channel subunits.Methods:2~8d after spinal nerve transection in rats model of chronic pain,the DRG were acutely isolated.The neuron discharge and sodium influx of medium-diameter DRG neurons were detected by the whole cell recording patch clamp tech-nique.The DRG neurons,the expression of sodium channel subunits were detected by RT-PCR.Results:the repetitive firing of DRG neurons in experiment was induced under current stimulation,However,the single action potential was induced in control.According to the voltage-clamp recordings,the amplitude of the fast and persistent sodium current of DRG neurons in experiment wAS both obviously higher than that in control group.Meanwhile,the expression of sodium channel subunits Nav1.3,Nav1.7 and Nav1.8 mRNA was obvi-ously higher.Conclusions:The sodium channel increased the excitability of DRG neurons in the spinal nerve,and the persistent sodium current could adjust the excitability of neurons by regulating the subthreshold membrane potential oscillation.