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Benzocaine enhances and inhibits the K+ current through a human cardiac cloned channel (Kv1.5)

Benzocaine enhances and inhibits the K+ current through a human cardiac cloned channel (Kv1.5) AbstractObjective: The aim of this study was to analyze the effects of a neutral local anaesthetic, benzocaine, on a cardiac K+ channel cloned from human ventricle. Methods: Experiments were performed on hKv1.5 channels stably expressed on mouse cells using the whole-cell configuration of the patch clamp technique. Results: At 10 nM, benzocaine increased the current amplitude (“agonist effect”) by shifting the activation curve 8.4±2.7 mV in the negative direction, and slowed the time course of tail current decline. In contrast, benzocaine (100–700 μM) inhibited hKv1.5 currents (KD=901±81 μM), modified the voltage-dependence of channel activation, which became biphasic, and accelerated the channel deactivation. Extracellular K+ concentration ([K+]o) also affected the channel gating. At 140 mM [K+]o, the time course of tail currents deactivation was significantly accelerated, whereas at 0 mM [K+]o, it was slowed. At both [K+]o the activation curve became biphasic. Benzocaine accelerated the tail current decay at 0 mM but not at 140 mM [K+]o. The reduction in the permeation of K+ through the pore did not modify the blocking effects of micromolar concentrations of benzocaine, but suppressed the agonist effect observed at nanomolar concentrations. Conclusions: All these results suggest that benzocaine blocks and modifies the voltage- and time-dependent properties of hKv1.5 channels, binding to an extracellular and to an intracellular site at the channel level. Moreover, both sites are related to each other and can also interact with K+. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Cardiovascular Research Oxford University Press

Benzocaine enhances and inhibits the K+ current through a human cardiac cloned channel (Kv1.5)

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References (26)

Publisher
Oxford University Press
Copyright
Copyright © 1999, European Society of Cardiology
ISSN
0008-6363
eISSN
1755-3245
DOI
10.1016/S0008-6363(99)00043-7
Publisher site
See Article on Publisher Site

Abstract

AbstractObjective: The aim of this study was to analyze the effects of a neutral local anaesthetic, benzocaine, on a cardiac K+ channel cloned from human ventricle. Methods: Experiments were performed on hKv1.5 channels stably expressed on mouse cells using the whole-cell configuration of the patch clamp technique. Results: At 10 nM, benzocaine increased the current amplitude (“agonist effect”) by shifting the activation curve 8.4±2.7 mV in the negative direction, and slowed the time course of tail current decline. In contrast, benzocaine (100–700 μM) inhibited hKv1.5 currents (KD=901±81 μM), modified the voltage-dependence of channel activation, which became biphasic, and accelerated the channel deactivation. Extracellular K+ concentration ([K+]o) also affected the channel gating. At 140 mM [K+]o, the time course of tail currents deactivation was significantly accelerated, whereas at 0 mM [K+]o, it was slowed. At both [K+]o the activation curve became biphasic. Benzocaine accelerated the tail current decay at 0 mM but not at 140 mM [K+]o. The reduction in the permeation of K+ through the pore did not modify the blocking effects of micromolar concentrations of benzocaine, but suppressed the agonist effect observed at nanomolar concentrations. Conclusions: All these results suggest that benzocaine blocks and modifies the voltage- and time-dependent properties of hKv1.5 channels, binding to an extracellular and to an intracellular site at the channel level. Moreover, both sites are related to each other and can also interact with K+.

Journal

Cardiovascular Research – Oxford University Press

Published: May 1, 1999

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