| The type of voltage-dependent K+ current that activates quickly at subthreshold potentials and inactivates quickly is referred to as the A-type K+ current (IA) in neurons. The I A in the dendrites of neurons has been thought to play an important role in regulating the excitability of the dendritic membrane and also to play a role in synaptic plasticity by regulating the invasion of back-propagating action potentials to the dendritic branches.; Kv4.2 is an A-type K+ channel localized to the dendrites and somata of neurons and has been hypothesized to give rise to a significant portion of the dendritic IA in neurons, particularly in the CA1 pyramidal neurons of the hippocampus.; Here, we describe the phenotype of mice with a targeted deletion of Kv4.2 (the Kv4.2 −/− mice). The Kv4.2 −/− mice are normal in growth rate, do not have spontaneous seizures, are fertile and live through adulthood. Field recordings in the CA1 area of the hippocampus revealed no differences between wildtype and Kv4.2 −/− mice in the input-output relationship of stimulus strength to synaptic response, paired pulse facilitation, posttetanic potentiation, long-term potentiation, long-term depression and frequency-response function. Whole-cell recordings of the CA1 pyramidal neurons revealed a possible compensatory current in the Kv4.2 −/− slices. However, the results so far have failed to demonstrate that Kv4.2 underlies the IA in CA1 neurons or to suggest any critical role that Kv4.2 plays in neurons. |
