AIM:To study the influence of lidocaine on transient outward potassium currents in
ventricular myocardium of rats, in order
to investigate whether the antiarrhythmic action of lidocaine is related to transient outward potassium currents. METHODS:The
ventricular myocardium of rats was quickly separated with the method of enzyme digestion,and the whole-cell patch clamp technique was used to record the influence of lidocaine on transient outward potassium currents of rats' ventricular myocardium,and then the dose-response curve was made,and the inhibitory concentration 50%(IC50) was also calculated. RESULTS:Lidocaine dose-
dependently blocked the transient outward potassium currents evoked by a voltage step from a holding potential of -80 mV to +70 mV.Transient outward potassium peak currents was reduced by(17.9±6.4)%by clinically relevant concentration of lidocaine(10 μmol/L) (t=7.986,P< 0.01),and when lidocaine was washed out,transient outward potassium could recover completely.Transient outward potassium currents were dose-dependently inhibited by lidocaine of 50,100,500,1 000,5 000 μmol/L.The inhibitive rates of current were(17.9±6.4)%,(25.2±4.4)%,(30.6±8.6)%,(53. 2±4.5)%,(71.8±8.9)%,(94.1±2.2)%respectively,andthe mean IC50 value was 672 μmol/L. CONCLUSION:Lidocaine can significantly inhibit the transient outward potassium currents in the ventricular myocardium of rats.