Regulation of cardiac inwardly rectifying potassium current IK1 and Kir2.x channels by endothelin-1.

To elucidate the ionic mechanism of endothelin-1 (ET-1)-induced focal ventricular tachyarrhythmias, the regulation of I(K1) and its main molecular correlates, Kir2.1, Kir2.2 and Kir2.

Inhibition of cardiac HERG channels by grapefruit flavonoid naringenin: implications for the influence of dietary compounds on cardiac repolarisation.

Flavonoids are naturally occurring food ingredients that have been associated with reduced cardiovascular mortality in epidemiological studies. In a previous study, we demonstrated for the first time that flavonoids are inhibitors of cardiac human ether-à-go-go-related gene (HERG) channels. Furthermore, we observed that grapefruit juice induced mild QTc prolongation in healthy subjects.

QTc prolongation by grapefruit juice and its potential pharmacological basis: HERG channel blockade by flavonoids.

Background: A high intake of dietary flavonoids, which are abundant in fruits, vegetables, tea, and wine, is known to reduce cardiovascular mortality. The effects of flavonoids on cardiac electrophysiology, which theoretically may have both antiarrhythmic and proarrhythmic consequences, have not been studied systematically to date.

Methods And Results: We screened a broad spectrum of flavonoids for their inhibitory activity on HERG channels by using heterologous expression in Xenopus oocytes.

Class Ia anti-arrhythmic drug ajmaline blocks HERG potassium channels: mode of action.

Ajmaline is a class Ia anti-arrhythmic drug used in several European countries and Japan as first-line treatment for ventricular tachyarrhythmia. Ajmaline has been reported to induce cardiac output (QT) prolongation and to inhibit cardiac potassium currents in guinea pig cardiomyocytes. In order to elucidate the molecular basis of these effects, we examined effects of ajmaline on human ether a-go-go related gene HERG potassium channels.