[Etomidate inhibits neuronal potassium channels in humans].

INTRODUCTION

There is no data available on the action of etomidate on ion currents in human neuronal cells. Therefore the effects of etomidate on a human neuronal delayed rectifier potassium current were investigated.

METHOD

Outward rectifying potassium currents of human neuroblastoma SH-SY5Y cells were measured using the whole cell patch-clamp technique. Cells were grown in RPMI-medium (+Pen/Strep and FCS) at 37 degrees C and 5% CO2. The holding potential was -80 mV. Potassium currents were evoked by depolarizing the membrane potential to values from -50 mV to +90 mV in 10 mV steps using an EPC-7 patch-clamp amplifier (List medical electronics) and pclamp version 5.71 (Axon instruments).

RESULTS

Etomidate differentially inhibited steady-state and peak potassium current with IC50-values of 170 microM for peak current suppression and 120 microM for steady-state current respectively. Etomidate induced inactivation-like behaviour of the potassium current and changed the voltage dependence of potassium current activation.

CONCLUSION

The results demonstrate that etomidate has more than one effect on the potassium current, indicating the complexity of general anaesthetic actions on neuronal targets. The actions of etomidate on human neuronal potassium currents may potentially contribute to the myocloni observed with this general anaesthetic agent during induction of anaesthesia.