Introduction: There is no data available on the action of etomidate on
ion currents in human neuronal cells. Therefore the effects of etomid
ate on a human neuronal delayed rectifer potassium current were invest
igated. Method: Outward rectifying potasium currents of human neurobla
stoma SH-SY5Y cells were measured using the whole cell patch-clamp tec
hnique. Cells were grown in RPMI-medium (+Pen/Strep and FCS) at 37 deg
rees C and 50% CO2. The holding potential was -80 mV. Potassium curren
ts 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 (L
ist medical electronics) and pclamp Version 5.71 (Axon instruments). R
esults: Etomidate differentially inhibited steady-state and peak potas
sium current with IC50-values of 170 mu M for peak current suppression
and 120 mu M for steady-state current, respectively. Etomidate induce
d inactivation-like behaviour of the potassium current and changed the
voltage dependence of potassium current activation. Conclusion: The r
esults demonstrate that etomidate has more than one effect on the pota
ssium current, indicating the complexity of general anaesthetic action
s on neuronal targets. The actions of etomidate on human neuronal pota
ssium currents may potentially contribute to the myocloni observed wit
h this general anaesthetic agent during induction of anaeshtesia.