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Block of HERG-carried K+ currents by the new repolarization delaying agent H 345/52.
J Cardiovasc Electrophysiol. 2003 Jun; 14(6):651-8.JC

Abstract

INTRODUCTION

The aim of this study was to analyze the block of HERG-carried membrane currents caused by H 345/52, a new antiarrhythmic compound with low proarrhythmic activity, in transfected mouse fibroblasts.

METHODS AND RESULTS

Using the whole-cell configuration of the voltage patch clamp technique, it was demonstrated that H 345/52 concentration-dependently blocked HERG-carried currents with an IC50 of 230 nM. H 345/52 preferentially bound to the open channel with unusually rapid kinetics and was trapped by channel closure. Voltage-independent behavior of H 345/52 was observed during both square-pulse and action potential clamp protocols. In contrast, the Class III agents dofetilide (10 nM) and almokalant (250 nM) demonstrated significant membrane potential-dependent effects during square-pulse clamp protocols. When using action potential clamp protocols, voltage dependence was seen with dofetilide but not with almokalant. Mathematical simulations of human ventricular action potentials predicted that the different voltage-dependent behaviors would not produce marked variations in action potential duration prolongation patterns.

CONCLUSION

We propose that block of IKr is the principal mechanism by which H 345/52 delays repolarization in human myocardium. The voltage independence of HERG/IKr block is unlikely to underlie the low proarrhythmic potential, and ancillary effects on other membrane currents must be considered.

Authors+Show Affiliations

AstraZeneca Research & Development Mölndal, Integrative Pharmacology, Mölndal, Sweden.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Evaluation Study
Journal Article

Language

eng

PubMed ID

12875428

Citation

Amos, Gregory J., et al. "Block of HERG-carried K+ Currents By the New Repolarization Delaying Agent H 345/52." Journal of Cardiovascular Electrophysiology, vol. 14, no. 6, 2003, pp. 651-8.
Amos GJ, Jacobson I, Duker G, et al. Block of HERG-carried K+ currents by the new repolarization delaying agent H 345/52. J Cardiovasc Electrophysiol. 2003;14(6):651-8.
Amos, G. J., Jacobson, I., Duker, G., & Carlsson, L. (2003). Block of HERG-carried K+ currents by the new repolarization delaying agent H 345/52. Journal of Cardiovascular Electrophysiology, 14(6), 651-8.
Amos GJ, et al. Block of HERG-carried K+ Currents By the New Repolarization Delaying Agent H 345/52. J Cardiovasc Electrophysiol. 2003;14(6):651-8. PubMed PMID: 12875428.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Block of HERG-carried K+ currents by the new repolarization delaying agent H 345/52. AU - Amos,Gregory J, AU - Jacobson,Ingemar, AU - Duker,Göran, AU - Carlsson,Leif, PY - 2003/7/24/pubmed PY - 2003/12/12/medline PY - 2003/7/24/entrez SP - 651 EP - 8 JF - Journal of cardiovascular electrophysiology JO - J. Cardiovasc. Electrophysiol. VL - 14 IS - 6 N2 - INTRODUCTION: The aim of this study was to analyze the block of HERG-carried membrane currents caused by H 345/52, a new antiarrhythmic compound with low proarrhythmic activity, in transfected mouse fibroblasts. METHODS AND RESULTS: Using the whole-cell configuration of the voltage patch clamp technique, it was demonstrated that H 345/52 concentration-dependently blocked HERG-carried currents with an IC50 of 230 nM. H 345/52 preferentially bound to the open channel with unusually rapid kinetics and was trapped by channel closure. Voltage-independent behavior of H 345/52 was observed during both square-pulse and action potential clamp protocols. In contrast, the Class III agents dofetilide (10 nM) and almokalant (250 nM) demonstrated significant membrane potential-dependent effects during square-pulse clamp protocols. When using action potential clamp protocols, voltage dependence was seen with dofetilide but not with almokalant. Mathematical simulations of human ventricular action potentials predicted that the different voltage-dependent behaviors would not produce marked variations in action potential duration prolongation patterns. CONCLUSION: We propose that block of IKr is the principal mechanism by which H 345/52 delays repolarization in human myocardium. The voltage independence of HERG/IKr block is unlikely to underlie the low proarrhythmic potential, and ancillary effects on other membrane currents must be considered. SN - 1045-3873 UR - https://www.unboundmedicine.com/medline/citation/12875428/Block_of_HERG_carried_K+_currents_by_the_new_repolarization_delaying_agent_H_345/52_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=1045-3873&date=2003&volume=14&issue=6&spage=651 DB - PRIME DP - Unbound Medicine ER -