Differential localization of rat Eag1 and Eag2 K⁺ channels in hippocampal neurons

Two isoforms of rat ether-à-go-go (Eag) K⁺ channels, rEag1 and rEag2, are widely expressed in many regions of the brain. The neurophysiological roles of these channels, however, are unclear. We addressed this issue by studying their subcellular localizations in hippocampal neurons. Immunofluorescence studies using markers for different compartments of neurons demonstrated a differential expression pattern of rEag1 and rEag1 K⁺ channels in the somatodendritic region. Furthermore, rEag1 K⁺ channels were in close proximity to synaptophysin and densin-180, but not GAD65. Our data suggest that both rEag1 and rEag1 K⁺ channels may play a pivotal role in the regulation of the excitability of dendrites and somas, and that rEag1 K⁺ channels may modulate the postsynaptic signaling of glutamatergic synapses.