Molecular site of action of the antiarrhythmic drug propafenone at the voltage-operated potassium channel Kv2.1.
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Molecular site of action of the antiarrhythmic drug propafenone at the voltage-operated potassium channel Kv2.1. / Madeja, Michael; Leicher, Thorsten; Friederich, Patrick; Punke, Mark Andree; Haverkamp, Wilhelm; Musshoff, Ulrich; Breithardt, Günter; Speckmann, Erwin-Josef.
In: MOL PHARMACOL, Vol. 63, No. 3, 3, 2003, p. 547-556.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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TY - JOUR
T1 - Molecular site of action of the antiarrhythmic drug propafenone at the voltage-operated potassium channel Kv2.1.
AU - Madeja, Michael
AU - Leicher, Thorsten
AU - Friederich, Patrick
AU - Punke, Mark Andree
AU - Haverkamp, Wilhelm
AU - Musshoff, Ulrich
AU - Breithardt, Günter
AU - Speckmann, Erwin-Josef
PY - 2003
Y1 - 2003
N2 - The effects of the antiarrhythmic drug propafenone at Kv2.1 channels were studied with wild-type and mutated channels expressed in Xenopus laevis oocytes. Propafenone decreased the Kv2.1 currents in a time- and voltage-dependent manner (decrease of the time constants of current rise, increase of block with the duration of voltage steps starting from a block of less than 19%, increase of block with the amplitude of depolarization yielding a fractional electrical distance delta of 0.11 to 0.16). Block of Kv2.1 appeared with application to the intracellular, but not the extracellular, side of membrane patches. In mutagenesis experiments, all parts of the Kv2.1 channel were successively exchanged with those of the Kv1.2 channel, which is much more sensitive to propafenone. The intracellular amino and carboxyl terminus and the intracellular linker S4-S5 reduced the blocking effect of propafenone, whereas the linker S5-S6, as well as the segment S6 of the Kv1.2 channel, abolished it to the value of the Kv1.2 channel. In the linker S5-S6, this effect could be narrowed down to two groups of amino acids (groups 372 to 374 and 383 to 384), which also affected the sensitivity to tetraethylammonium. In segment S6, several amino acids in the intracellularly directed part of the helix significantly reduced propafenone sensitivity. The results suggest that propafenone blocks the Kv2.1 channel in the open state from the intracellular side by entering the inner vestibule of the channel. These results are consistent with a direct interaction of propafenone with the lower part of the pore helix and/or residues of segment S6.
AB - The effects of the antiarrhythmic drug propafenone at Kv2.1 channels were studied with wild-type and mutated channels expressed in Xenopus laevis oocytes. Propafenone decreased the Kv2.1 currents in a time- and voltage-dependent manner (decrease of the time constants of current rise, increase of block with the duration of voltage steps starting from a block of less than 19%, increase of block with the amplitude of depolarization yielding a fractional electrical distance delta of 0.11 to 0.16). Block of Kv2.1 appeared with application to the intracellular, but not the extracellular, side of membrane patches. In mutagenesis experiments, all parts of the Kv2.1 channel were successively exchanged with those of the Kv1.2 channel, which is much more sensitive to propafenone. The intracellular amino and carboxyl terminus and the intracellular linker S4-S5 reduced the blocking effect of propafenone, whereas the linker S5-S6, as well as the segment S6 of the Kv1.2 channel, abolished it to the value of the Kv1.2 channel. In the linker S5-S6, this effect could be narrowed down to two groups of amino acids (groups 372 to 374 and 383 to 384), which also affected the sensitivity to tetraethylammonium. In segment S6, several amino acids in the intracellularly directed part of the helix significantly reduced propafenone sensitivity. The results suggest that propafenone blocks the Kv2.1 channel in the open state from the intracellular side by entering the inner vestibule of the channel. These results are consistent with a direct interaction of propafenone with the lower part of the pore helix and/or residues of segment S6.
M3 - SCORING: Zeitschriftenaufsatz
VL - 63
SP - 547
EP - 556
JO - MOL PHARMACOL
JF - MOL PHARMACOL
SN - 0026-895X
IS - 3
M1 - 3
ER -