Physiological roles of Kv2 channels in entorhinal cortex layer II stellate cells revealed by Guangxitoxin‐1E

Kv2 channels underlie delayed‐rectifier potassium currents in various neurons, although their physiological roles often remain elusive. Almost nothing is known about Kv2 channel functions in medial entorhinal cortex (mEC) neurons, which are involved in representing space, memory formation, epilepsy and dementia. Stellate cells in layer II of the mEC project to the hippocampus and are considered to be space‐representing grid cells. We used the new Kv2 blocker Guangxitoxin‐1E (GTx) to study Kv2 functions in these neurons. Voltage clamp recordings from mEC stellate cells in rat brain slices showed that GTx inhibited delayed‐rectifier K+ current but not transient A‐type current. In current clamp, GTx had multiple effects: (i) increasing excitability and bursting at moderate spike rates but reducing firing at high rates; (ii) enhancing after‐depolarizations; (iii) reducing the fast and medium after‐hyperpolarizations; (iv) broadening action potentials; and (v) reducing spike clustering. GTx is a useful tool for studying Kv2 channels and their functions in neurons.