Phencyclidine at low concentrations selectively blocks the sustained but not the transient voltage-dependent potassium current in cultured hippocampal neurons.

We studied the effects of phencyclidine (PCP) on voltage-dependent K+ currents in cultured embryonic rat hippocampal neurons. Whole cell voltage-clamp recordings were made in the presence of tetrodotoxin to block Na+ current. Depolarizing voltage steps activated two outward current components: (i) a rapidly activating and inactivating ('transient') component, IA, and (ii) a slowly activating, minimally inactivating ('sustained'), component, IK. At low concentrations (less than 50-100 microM), PCP produced a selective, reversible blockade of IK with minimal effect on IA; however, at higher concentrations both currents were suppressed. The IC50's for blockade of IK and IA were 36 and 310 microM, respectively.