STABLE EXPRESSION AND CHARACTERIZATION OF THE HUMAN BRAIN POTASSIUM CHANNEL KV2.1 - BLOCKADE BY ANTIPSYCHOTIC AGENTS

We have cloned the cDNA encoding the voltage-dependent K+ channel Kv2. 1 from human brain (hKv2.1). RNase protection and RT-PCR (reverse tran scriptase-PCR) experiments reveal abundant Kv2.1 transcripts in human brain with virtually no expression detectable in human heart. hKv2.1 h as been stably transfected into a human glioblastoma cell Line, and tr ansformed cells display large, slowly activating outward currents. The kinetics, steady-state activation and inactivation parameters, and ex ternal tetraethylammonium sensitivity were all similar to those descri bed previously for hKv2.1 channels transiently expressed in Xenopus oo cytes or other mammalian fell. lines. A number of dopamine receptor an tagonist/antipsychotic agents were shown to block hKv2.1. Trifluoperiz ine, trifluperidol and pimozide produced time-dependent blockade of hK v2.1 with IC50 values of approx. 1-2 mu M. The diphenylbutylpiperidine fluspirilene was shown to be 4-5-fold more potent than the other agen ts tested inhibiting hKv2.1 current with an IC50 value of 297 nM. The block produced by fluspirilene was both time- and frequency-dependent. Furthermore, fluspirilene (1 mu M) shifted the midpotential of the hK v2.1 steady-state inactivation curve by approx. 15 mV in the hyperpola rizing direction. These results demonstrate the usefulness of this tra nsfection system for the pharmacological characterization of hKv2.1. F luspirilene proved to be a relatively potent blocker of hKv2.1 and may provide a useful starting point for the development of more potent an d selective agents active against this brain K+ channel.