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

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