The potassium channels Kv1.5 and Kv1.3 modulate distinct functions of microglia.

Activation of microglia by LPS leads to an induction of cytokine and NO release, reduced proliferation and increased outward K(+) conductance, the latter involving the activation of Kv1.5 and Kv1.3 channels. We studied the role of these channels for microglial function using two strategies to interfere with channel expression, a Kv1.5 knockout (Kv1.5(-/-)) mouse and an antisense oligonucleotide (AO) approach. The LPS-induced NO release was reduced by AO Kv1.5 and completely absent in the Kv1.5(-/-) animal; the AO Kv1.3 had no effect. In contrast, proliferation was augmented with both, loss of Kv1.3 or Kv1.5 channel expression. After facial nerve lesion, proliferation rate was higher in Kv1.5(-/-) animals as compared to wild type. Patch clamp experiments confirmed the reduction of the LPS-induced outward current amplitude in Kv1.5(-/-) microglia as well as in Kv1.5- or Kv1.3 AO-treated cells. Our study indicates that induction of K(+) channel expression is a prerequisite for the full functional spectrum of microglial activation.