Molecular cloning and functional expression of a potassium channel cDNA isolated from a rat cardiac library

A full‐length K+ channel cDNA (RHK1) was isolated from a rat cardiac library using the polymerase chain reaction (PCR) method and degenerate oligonucleotide primers derived from K+ channel sequences conserved between Drosophila Shaker H4 and mouse brain MBK1. Although RHK1 was isolated from heart, its expression was found in both heart and brain. The RHK1‐encoded protein, when expressed in Xenopus oocytes, gated a 4‐aminopyridine (4‐AP)‐sensitive transient outward current. This current is similar to the transient outward current measured in rat ventricular myocytes with respect to voltage‐dependence of activation and inactivation, time course of activation and inactivation, and pharmacology.

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