Molecular determinants of external barium block inShakerpotassium channels
نویسندگان
چکیده
منابع مشابه
Molecular determinants of dofetilide block of HERG K+ channels.
The human ether-a-go-go-related gene (HERG) encodes a K+ channel with biophysical properties nearly identical to the rapid component of the cardiac delayed rectifier K+ current (IKr). HERG/IKr channels are a prime target for the pharmacological management of arrhythmias and are selectively blocked by class III antiarrhythmic methanesulfonanilide drugs, such as dofetilide, E4031, and MK-499, at ...
متن کاملExternal barium block of Shaker potassium channels: evidence for two binding sites
External barium ions inhibit K+ currents of Xenopus oocytes expressing ShH4 delta 6-46, the non-inactivating deletion of the Shaker K+ channel. At the macroscopic level, Ba2+ block comprises both a fast and a slow component. The fast component is less sensitive to Ba2+ (apparent dissociation constant at 0 mV, K(0), approximately 19.1 mM) than the slow component and is also less voltage dependen...
متن کاملPotassium-selective block of barium permeation through single KcsA channels
Ba(2+), a doubly charged analogue of K(+), specifically blocks K(+) channels by virtue of electrostatic stabilization in the permeation pathway. Ba(2+) block is used here as a tool to determine the equilibrium binding affinity for various monovalent cations at specific sites in the selectivity filter of a noninactivating mutant of KcsA. At high concentrations of external K(+), the block-time di...
متن کاملExternal Barium Affects the Gating of KCNQ1 Potassium Channels and Produces a Pore Block via Two Discrete Sites
The pore properties and the reciprocal interactions between permeant ions and the gating of KCNQ channels are poorly understood. Here we used external barium to investigate the permeation characteristics of homomeric KCNQ1 channels. We assessed the Ba(2+) binding kinetics and the concentration and voltage dependence of Ba(2+) steady-state block. Our results indicate that extracellular Ba(2+) ex...
متن کاملMolecular determinants of HERG channel block.
Drug-induced block of cardiac hERG K+ channels causes acquired long QT syndrome. Here, we characterized the molecular mechanism of hERG block by two low-potency drugs (Nifekalant and bepridil) and two high-potency drugs 1-[2-(6-methyl-2pyridyl)ethyl]-4-(4-methylsulfonyl aminobenzoyl)piperidine (E-4031) and dofetilide). Channels were expressed in Xenopus laevis oocytes, and currents were measure...
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ژورنال
عنوان ژورنال: FEBS Letters
سال: 1996
ISSN: 0014-5793
DOI: 10.1016/0014-5793(96)00516-9