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Ketamine and propofol differentially inhibit human neuronal K+ channels

Published online by Cambridge University Press:  16 August 2006

P. Friederich ,
D. Benzenberg  and
B. W. Urban
P. Friederich
Affiliation:
Department of Anaesthesiology and Intensive Care Medicine, University of Bonn, Germany
D. Benzenberg
Affiliation:
Department of Anaesthesiology and Intensive Care Medicine, University of Bonn, Germany
B. W. Urban
Affiliation:
Department of Anaesthesiology and Intensive Care Medicine, University of Bonn, Germany Departments of Anesthesiology and Physiology, Weill Medical College of Cornell University, New York, New York, USA
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Abstract

Background and objective Interaction of intravenous anaesthetic agents with voltage-dependent potassium channels significantly correlates with clinical concentrations. If potassium channels were to play an important part in anaesthesia, one might expect different effects at the molecular level of those anaesthetics that show different clinical effects. Our aim was to analyse the interaction of general anaesthetics with voltage-dependent K channels.

Methods Whole cell patch-clamp experiments were analysed in detail in order to compare the effects of two clinically diverse intravenous hypnotics, ketamine and propofol, on voltage-dependent potassium channels in human neuroblastoma SH-SY5Y cells.

Results Both anaesthetics inhibited the potassium conductance in a concentration-dependent and reversible manner with IC50-values of 300μM and 45μM for ketamine and propofol respectively. Whereas ketamine shifted the midpoint of current activation by maximally 14 mV to more hyperpolarized potentials, propofol had the opposite effect on the activation midpoint. Current inhibition by ketamine increased with voltage but decreased with propofol at higher membrane potentials. Propofol but not ketamine induced concentration-dependent but voltage-independent decline, akin to inactivation, of the voltage-dependent potassium channels.

Conclusions The anaesthetics differed not only in their clinical profiles but they also showed differential actions on voltage-dependent potassium channels in several ways. This provides additional evidence for the hypothesis that voltage-dependent potassium channels play an important role in anaesthesia.

Keywords

anaestheticsintravenousketaminepropofolanaesthetic mechanismsK channels
Type
Original Article
Information
European Journal of Anaesthesiology , Volume 18 , Issue 3 , March 2001 , pp. 177 - 183
Copyright
2001 European Society of Anaesthesiology

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