Gamma-dendrotoxin blocks large conductance Ca2+-activated K+ channels in neuroblastoma cells

Inhibition of the human ether-a-go-go-related gene (HERG) K+ channels by Lindera erythrocarpa

Lindera erythrocarpa Makino (Lauraceae) is used as a traditional medicine for analgesic, antidote, and antibacterial purposes and shows anti-tumor activity. We studied the effects of Lindera erythrocarpa on the human ether-a-go-go-related gene (HERG) channel, which appears of importance in favoring cancer progression in vivo and determining cardiac action potential duration. Application of MeOH extract of Lindera erythrocarpa showed a dose-dependent decrease in the amplitudes of the outward currents measured at the end of the pulse (I(HERG)) and the tail currents of HERG (I(tail)). When the BuOH fraction and H(2)O fraction of Lindera erythrocarpa were added to the perfusate, both I(HERG) and I(tail) were suppressed, while the hexane fraction, CHCl(3) fraction, and EtOAc fraction did not inhibit either I(HERG) or I(tail). The potential required for half-maximal activation caused by EtOAc fraction, BuOH fraction, and H(2)O fraction shifted significantly. The BuOH fraction and H(2)O fraction (100 microg/mL) decreased g(max) by 59.6% and 52.9%, respectively. The H(2)O fraction- and BuOH fraction-induced blockades of I(tail) progressively decreased with increasing depolarization, showing the voltage-dependent block. Our findings suggest that Lindera erythrocarpa, a traditional medicine, blocks HERG channel, which could contribute to its anticancer and cardiac arrhythmogenic effect.