The Distributions of Voltage-Gated K + current Subtypes in Different Cell Sizes from Adult Mouse Dorsal Root Ganglia.

Voltage-gated K+ (KV ) currents play a crucial role in regulating pain by controlling neuronal excitability, and are divided into transient A-type currents (IA ) and delayed rectifier currents (IK ). The dorsal root ganglion (DRG) neurons are heterogeneous and the subtypes of KV currents display different levels in distinct cell sizes. To observe correlations of the subtypes of KV currents with DRG cell sizes, KV currents were recorded by whole-cell patch clamp in freshly isolated mouse DRG neurons. Results showed that IA occupied a high proportion in KV currents in medium- and large-diameter DRG neurons, whereas IK possessed a larger proportion of KV currents in small-diameter DRG neurons. A lower correlation was found between the proportion of IA or IK in KV currents and cell sizes. These data suggest that IA channels are mainly expressed in medium and large cells and IK channels are predominantly expressed in small cells.