RT Journal Article
T1 Propafenone blocks human cardiac Kir2.x channels by decreasing the negative electrostatic charge in the cytoplasmic pore
A1 Amorós García, Irene
A1 Dolz Gaitón, Pablo
A1 Gómez García, Ricardo
A1 Matamoros, Marcos
A1 Barana Muñoz, Adriana
A1 González de la Fuente, Marta
A1 Núñez, Mercedes
A1 Pérez Hernández, Marta
A1 Moraleda, Ignacio
A1 Gálvez Ruano, Enrique
A1 Iriepa, Isabel
A1 Tamargo Menéndez, Juan
A1 Caballero Collado, Ricardo
A1 Delpón Mosquera, María Eva
AB Human cardiac inward rectifier current (IK1) is generated by Kir2.x channels. Inhibition of IK1 could offer a useful antiarrhythmic strategy against fibrillatory arrhythmias. Therefore, elucidation of Kir2.x channels pharmacology, which still remains elusive, is mandatory. We characterized the electrophysiological and molecular basis of the inhibition produced by the antiarrhythmic propafenone of the current generated by Kir2.x channels (IKir2.x) and the IK1 recorded in human atrial myocytes. Wild type and mutated human Kir2.x channels were transiently transfected in CHO and HEK-293 cells. Macroscopic and single-channel currents were recorded using the patch-clamp technique. At concentrations >1μM propafenone inhibited IKir2.x the order of potency being Kir2.3∼IK1>Kir2.2>Kir2.1 channels. Blockade was irrespective of the extracellular K(+) concentration whereas markedly increased when the intracellular K(+) concentration was decreased. Propafenone decreased inward rectification since at potentials positive to the K(+) equilibrium potential propafenone-induced block decreased in a voltage-dependent manner. Importantly, propafenone favored the occurrence of subconductance levels in Kir2.x channels and decreased phosphatidylinositol 4,5-bisphosphate (PIP2)-channel affinity. Blind docking and site-directed mutagenesis experiments demonstrated that propafenone bound Kir2.x channels at the cytoplasmic domain, close to, but not in the pore itself, the binding site involving two conserved Arg residues (residues 228 and 260 in Kir2.1). Our results suggested that propafenone incorporated into the cytoplasmic domain of the channel in such a way that it decreased the net negative charge sensed by K(+) ions and polyamines which, in turn, promotes the appearance of subconductance levels and the decrease of PIP2 affinity of the channels.
PB Elsevier
SN 0006-2952
YR 2013
FD 2013-07-15
LK https://hdl.handle.net/20.500.14352/100150
UL https://hdl.handle.net/20.500.14352/100150
LA eng
NO Ministerio de Ciencia e Innovación
NO Instituto de Salud Carlos III
NO Centro Nacional de Investigaciones Cardiovasculares
NO Comunidad Autónoma de Madrid
NO Sociedad Española de Cardiología
DS Docta Complutense
RD 10 abr 2025