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State-dependent barium block of wild-type and inactivation-deficient HERG channels in Xenopus oocytes.
Weerapura M
,
Nattel S
,
Courtemanche M
,
Doern D
,
Ethier N
,
Hebert T
.
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The effects of Ba2+ on current resulting from the heterologous expression of the human ether-à-go-go related gene (HERG) (IHERG) was studied with two-electrode voltage clamp techniques in Xenopus oocytes. Ba2+ produced time- and voltage-dependent block of IHERG. Significant inhibition was seen at concentrations as low as 1 microM. Inhibition was greatest at step potentials between -40 and 0 mV; at more positive potentials, inhibition decreased in association with time-dependent unblocking of channels. An inactivation-attenuated mutant of HERG (S631A) was prepared and expressed in Xenopus oocytes. Ba2+ block of S631A differed from that of HERG in that extensive unblocking was no longer seen at positive potentials and the voltage dependence of step current block was greatly attenuated. A mathematical model was applied to analyse quantitatively the inhibitory effects of Ba2+ on IHERG. The model suggested similar voltage-dependent affinity of Ba2+ for the open and closed states, along with absence of binding to the inactivated state, and accounted well for Ba2+ effects on both wild-type and S631A channels. We conclude that Ba2+ potently inhibits IHERG in a characteristic state-dependent fashion, with strong unblocking at positive potentials related to the presence of an intact C-type inactivation mechanism.
Abbott,
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1999, Pubmed,
Xenbase
Abbott,
MiRP1 forms IKr potassium channels with HERG and is associated with cardiac arrhythmia.
1999,
Pubmed
,
Xenbase
Anumonwo,
Delayed rectification in single cells isolated from guinea pig sinoatrial node.
1992,
Pubmed
Armstrong,
Block of squid axon K channels by internally and externally applied barium ions.
1982,
Pubmed
Balser,
Time-dependent outward current in guinea pig ventricular myocytes. Gating kinetics of the delayed rectifier.
1990,
Pubmed
Barhanin,
K(V)LQT1 and lsK (minK) proteins associate to form the I(Ks) cardiac potassium current.
1996,
Pubmed
,
Xenbase
Barry,
Myocardial potassium channels: electrophysiological and molecular diversity.
1996,
Pubmed
Basso,
Pore accessibility during C-type inactivation in Shaker K+ channels.
1998,
Pubmed
Berthet,
C-terminal HERG mutations: the role of hypokalemia and a KCNQ1-associated mutation in cardiac event occurrence.
1999,
Pubmed
Brochu,
Pacemaker current in single cells and in aggregates of cells dissociated from the embryonic chick heart.
1992,
Pubmed
Carmeliet,
Characterization of the acetylcholine-induced potassium current in rabbit cardiac Purkinje fibres.
1986,
Pubmed
Colatsky,
Channel specificity in antiarrhythmic drug action. Mechanism of potassium channel block and its role in suppressing and aggravating cardiac arrhythmias.
1990,
Pubmed
Curran,
A molecular basis for cardiac arrhythmia: HERG mutations cause long QT syndrome.
1995,
Pubmed
DiFrancesco,
Barium-induced blockade of the inward rectifier in calf Purkinje fibres.
1984,
Pubmed
Eaton,
Effects of barium on the potassium conductance of squid axon.
1980,
Pubmed
Fermini,
Removal of sialic acid alters both T- and L-type calcium currents in cardiac myocytes.
1991,
Pubmed
Ficker,
Molecular determinants of dofetilide block of HERG K+ channels.
1998,
Pubmed
,
Xenbase
Giles,
Voltage clamp of bull-frog cardiac pace-maker cells: a quantitative analysis of potassium currents.
1985,
Pubmed
Gillis,
The effects of barium, dofetilide and 4-aminopyridine (4-AP) on ventricular repolarization in normal and hypertrophied rabbit heart.
1998,
Pubmed
Harris,
A permanent ion binding site located between two gates of the Shaker K+ channel.
1998,
Pubmed
,
Xenbase
Hebert,
Voltage dependencies of the fast and slow gating modes of RIIA sodium channels.
1994,
Pubmed
,
Xenbase
Ho,
Voltage-dependent blockade of HERG channels expressed in Xenopus oocytes by external Ca2+ and Mg2+.
1998,
Pubmed
,
Xenbase
Ho,
Blockade of HERG channels expressed in Xenopus laevis oocytes by external divalent cations.
1999,
Pubmed
,
Xenbase
Hurst,
External barium block of Shaker potassium channels: evidence for two binding sites.
1995,
Pubmed
,
Xenbase
Hurst,
Molecular determinants of external barium block in Shaker potassium channels.
1996,
Pubmed
,
Xenbase
Kiehn,
Molecular physiology and pharmacology of HERG. Single-channel currents and block by dofetilide.
1996,
Pubmed
,
Xenbase
Li,
Evidence for two components of delayed rectifier K+ current in human ventricular myocytes.
1996,
Pubmed
Miller,
Coupling of voltage-dependent gating and Ba++ block in the high-conductance, Ca++-activated K+ channel.
1987,
Pubmed
Noble,
Outward membrane currents activated in the plateau range of potentials in cardiac Purkinje fibres.
1969,
Pubmed
Paquette,
Effects of divalent cations on the E-4031-sensitive repolarization current, I(Kr), in rabbit ventricular myocytes.
1998,
Pubmed
Sanguinetti,
A mechanistic link between an inherited and an acquired cardiac arrhythmia: HERG encodes the IKr potassium channel.
1995,
Pubmed
,
Xenbase
Sanguinetti,
Coassembly of K(V)LQT1 and minK (IsK) proteins to form cardiac I(Ks) potassium channel.
1996,
Pubmed
,
Xenbase
Sanguinetti,
Two components of cardiac delayed rectifier K+ current. Differential sensitivity to block by class III antiarrhythmic agents.
1990,
Pubmed
Sanguinetti,
Delayed rectifier outward K+ current is composed of two currents in guinea pig atrial cells.
1991,
Pubmed
Shimoni,
Role of an inwardly rectifying potassium current in rabbit ventricular action potential.
1992,
Pubmed
Smith,
The inward rectification mechanism of the HERG cardiac potassium channel.
1996,
Pubmed
Spector,
Fast inactivation causes rectification of the IKr channel.
1996,
Pubmed
,
Xenbase
Taglialatela,
Barium blockade of a clonal potassium channel and its regulation by a critical pore residue.
1993,
Pubmed
,
Xenbase
Trudeau,
HERG, a human inward rectifier in the voltage-gated potassium channel family.
1995,
Pubmed
WERMAN,
Graded and all-or-none electrogenesis in arthropod muscle. II. The effects of alkali-earth and onium ions on lobster muscle fibers.
1961,
Pubmed
Wang,
Positional cloning of a novel potassium channel gene: KVLQT1 mutations cause cardiac arrhythmias.
1996,
Pubmed
Wang,
A quantitative analysis of the activation and inactivation kinetics of HERG expressed in Xenopus oocytes.
1997,
Pubmed
,
Xenbase
Wang,
Modulation of HERG affinity for E-4031 by [K+]o and C-type inactivation.
1997,
Pubmed
,
Xenbase
Zang,
Barium block of the muscarinic potassium current in guinea-pig atrial cells.
1995,
Pubmed
Zou,
Single HERG delayed rectifier K+ channels expressed in Xenopus oocytes.
1997,
Pubmed
,
Xenbase
Zou,
A mutation in the pore region of HERG K+ channels expressed in Xenopus oocytes reduces rectification by shifting the voltage dependence of inactivation.
1998,
Pubmed
,
Xenbase
