AIM: To determine the mechanisms of interactions between different drugs and HERG channels. METHODS: Various antiarrhythmic (dofetilide, quinidine, azimilide, RP58866) and non-antiarrhythmic (terfenadine, nicotine) agents were used on HERG channels expressed in Xenopus oocyte. Whole-cell voltage-clamp techniques were used. RESULTS: All drugs produced concentration-dependent block of HERG current. The inhibition was markedly facilitated with voltage protocols favoring channel inactivation (eg, less negative holding potentials). Maneuvers that weakened channel inactivation (eg, elevation of external K+), relieved HERG blockade by all drugs. Moreover, the inhibitory potency was reduced by at least 20-300 fold with varying compounds when rapid C-type inactivation was removed by a mutation located between the transmembrane domains 5 and 6 (S631A). CONCLUSION: The inactivation gating of HERG channels determines the blocking potency of drugs. This mechanism might be common to drugs of various classes.
AIM: To determine the mechanisms of interactions between different drugs and HERG channels. METHODS: Various antiarrhythmic (dofetilide, quinidine, azimilide, RP58866) and non-antiarrhythmic (terfenadine, nicotine) agents were used on HERG channels expressed in Xenopus oocyte. Whole-cell voltage-clamp techniques were used. RESULTS: All drugs produced concentration-dependent block of HERG current. The inhibition was markedly facilitated with voltage protocols favoring channel inactivation (eg, less negative holding potentials). Maneuvers that weakened channel inactivation (eg, elevation of external K+), relieved HERG blockade by all drugs. Moreover, the inhibitory potency was reduced by at least 20-300 fold with varying compounds when rapid C-type inactivation was removed by a mutation located between the transmembrane domains 5 and 6 (S631A). CONCLUSION: The inactivation gating of HERG channels determines the blocking potency of drugs. This mechanism might be common to drugs of various classes.
Authors: Francisco G Sanchez-Conde; Eric N Jimenez-Vazquez; David S Auerbach; David K Jones Journal: Front Mol Neurosci Date: 2022-05-03 Impact factor: 6.261
Authors: R S Duncan; M J McPate; J M Ridley; Z Gao; A F James; D J Leishman; J L Leaney; H J Witchel; J C Hancox Journal: Biochem Pharmacol Date: 2007-05-03 Impact factor: 5.858