Potassium currents in developing neurons.

In Xenopus spinal neurons, delayed rectifier type voltage-dependent potassium currents (IKv) are developmentally regulated. These currents play a pivotal role in maturation of the action potential from a long-duration calcium-dependent impulse to a brief sodium-dependent one. Although spinal neurons are heterogeneous, IKv undergoes a synchronized and homogeneous developmental functional up-regulation across this diverse population of motor, sensory, and interneurons. This finding suggested that the diverse population of neurons expressed a common potassium channel. Thus, recent efforts have been directed towards cloning the relevant potassium channel gene. However, these molecular studies reveal an unsuspected heterogeneity in the molecular components of voltage-dependent potassium channels. Further, synchronous differentiation of IKv is achieved via heterogeneous Kv channel gene expression.