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

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