Deletion of the KV1.1 Potassium Channel Causes Epilepsy in Mice

Abstract

Mice lacking the voltage-gated potassium channel α subunit, KV1.1, display frequent spontaneous seizures throughout adult life. In hippocampal slices from homozygous KV1.1 null animals, intrinsic passive properties of CA3 pyramidal cells are normal. However, antidromic action potentials are recruited at lower thresholds in KV1.1 null slices. Furthermore, in a subset of slices, mossy fiber stimulation triggers synaptically mediated long-latency epileptiform burst discharges. These data indicate that loss of KV1.1 from its normal localization in axons and terminals of the CA3 region results in increased excitability in the CA3 recurrent axon collateral system, perhaps contributing to the limbic and tonic–clonic components of the observed epileptic phenotype. Axonal action potential conduction was altered as well in the sciatic nerve—a deficit potentially related to the pathophysiology of episodic ataxia/myokymia, a disease associated with missense mutations of the human KV1.1 gene.