Effect of ketamine on transient outward potassium current of isolated human atrial myocytes

The effects of ketamine on transient outward potassium current(Ito) of isolated human atrial myocytes were investigated to understand the mechanism of part of its effects by whole-cell patch-clamp.Atrial myocytes were enzymatically isolated from specimens of human atrial appendage obtained from patients under going cardiac valve displacing.Ito is recorded in voltage-clamp modes using the patch-clamp technique at room temperature.Currents signals were recorded by an Axopatch 200B amplifier with the Digidata 1322A-pClamp 9.0 data acquisition system.Ketamine decreased Ito of human atrial myocytes in a dose-dependent manner.The current-voltage curve was significantly lowered,30,100,300,and 1000 μmol·L-1 ketamine decreased respectively Ito current density about(13.62 ± 0.04)%,(38.92 ± 0.05)%,(72.24 ± 0.10)% and(83.84 ± 0.05)% at the potential of 50 mV,with an IC50 of 121 μmol·L-1.The Ito activation curve,inactivation curve and the recovery curve were not altered by ketamine.So,ketamine concentration-dependently decreased Ito of human atrial myocytes.