We have experimented with freshly isolated single DRG neurons from neonatal (P0-5) rats to study currents mediated by voltage dependent Na⁺ (Nav) channels. All experiments were performed using the whole-cell mode of patch-clamp electrophysiology and following the standard steps of this technique. However, in a subgroup of neurons, spontaneous events resembling neurotransmitter release were observed under conditions optimized for whole-cell patch-clamp recordings of I_Na. All events have a fast rise phase (similar to responses of receptor channels), but decay in a heterogeneous manner. The waveform of the event closely matches that of the response of the purinergic receptor P2X type to ATP. This new activity in neurons was observed at -60 mV and was facilitated during relatively strong hyperpolarization. Although spontaneous fluctuations, termed membrane potential instabilities, are described in DRG neurons, the observed inward currents at more hyperpolarized states are distinct and novel. The spontaneous heterogeneous activities could be relevant to the elucidation of pain mechanisms by distinct pharmacological tools.

Keywords: Ion channels; nonsynaptic neurotransmission; patch-clamp.

我们使用新生鼠（P0-5天）新鲜分离的单个DRG神经元，研究了由电压依赖性钠通道(Nav)介导的电流。所有实验均采用全细胞模式的膜片钳电生理技术进行，并遵循该技术的标准步骤。然而，在一部分神经元中，观察到在优化条件下用于记录I_Na的全细胞膜片钳记录中出现了类似递质释放的自发事件。所有这些事件都具有快速上升相（类似于受体通道响应），但衰减方式各异。该事件的波形与嘌呤能受体P2X型对ATP的反应形式非常相似。这种新的神经元活性在-60毫伏时被观察到，并且在相对较强的超极化状态下得到增强。尽管已经描述了DRG神经元中的自发波动（称为膜电位不稳定性），但在更加超极化的状态下的内向电流是独特的和新颖的。这些不同寻常的自发活动可能通过不同的药理工具与疼痛机制的研究相关联。

关键词：离子通道；非突触递质传递；膜片钳技术。