A novel cardiac potassium channel that is active and conductive at depolarized potentials.
We report the existence of a novel potassium channel revealed in single-channel recordings from guinea-pig ventricular heart cells. The channel, observed in approximately 10% of patches, demonstrates a 14 pS conductance at physiological potassium concentrations, does not rectify over the voltage range of the action potential, and is quite selective for K ions. The channel activates with depolarization, but does not require intracellular Ca2+ ions to open. Open channel probability increases rapidly (less than 10 ms) to a plateau in response to depolarizing voltage steps, and demonstrates no detectable inactivation (greater than 600 ms). These features clearly distinguish this channel from other known K channels in cardiac muscle. Because of its high activity at plateau potentials, we propose the name iKp.
Yue
D T
DT
Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205.
Marban
E
E
D000818:Animals; D006168:Guinea Pigs; D006321:Heart / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009206:Myocardium / Q000166:cytology*; D015221:Potassium Channels / Q000502:physiology*; D016276:Ventricular Function
D015221:Potassium Channels