Blockade action of ketanserin and increasing effect of potassium ion on Kv1.3 channels expressed in Xenopus oocytes

The goal of this study was to investigate the pharmacological effects of ketanserin (KT) and elevated extracellular potassium ([K+]o) on Kv1.3 potassium channels. Kv1.3 channels were expressed in Xenopus oocytes, and the resulting currents were measured using a two-microelectrode voltage-clamp technique. KT blocked Kv1.3 currents in a concentration-dependent, time-dependent and voltage-independent manner, and accelerated their activation and inactivation. Kv1.3 currents were increased by high [K+]o in a concentration-dependent manner. Our results suggest that KT acts directly on the open state of the Kv1.3 channel, whereas augmentation of extracellular [K] enhances current flow through the channel by increasing the channel's conductance.