Effects of different concentrations of chloroprocaine on KCNQ2/Q3 channel currents in HEK2936 cells / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effects of different concentrations of chloroprocaine on KCNQ2/Q3 channel currents in HEK2936 cells.Methods Human embryonic kidney (HEK293) cells served as an expression system.KCNQ2 and KCNQ3 cDNAs and green fluorescent protein were transfected into HEK293 cells by using lipofectamine.The KCNQ2/Q3 currents were recorded by using the whole-cell patch-clamp technique.Part Ⅰ The transfected HEK293 cells were randomly divided into 4 groups (n =11 each)control group,and 1,10 and 100 mmol/L chloroprocaine groups.The KCNQ2/Q3 channel currents produced by different concentrations of chloroprocaine were recorded under different holding potentials (-40,0 and 40 mV) and the action time was 1 min.Part Ⅱ The transfected HEK293 cells were randomly divided into 2 groups (n =5 each)control group and 10 mmol/L chloroprocaine.The KCNQ2/Q3 channel currents were recorded under different holding potentials (-80-30 mV)and the action time was 1 min.Different test potentials were normalized and fitted to Boltzmann function,and KCNQ2/Q3 channel Ⅰ-Ⅴ curve was then obtained.The activation and deactivation currents were both fitted to a single exponential function and the time constants for current activation and for current deactivation were calculated.Results Part Ⅰ When the holding potential was 40,0 and-40 mV,the suppression rate of KCNQ2/Q3 channel currents in HEK293 cells was higher in 1,10 and 100 mmol/L chloroprocaine groups than in control group (P ＜0.05 or 0.01).Part Ⅱ Compared with control group,the time constant for the current activation at 0 mV of holding potential was prolonged,the time constant for the current deactivation was shortened when the holding potential was-80 mV,and the half-activation voltage of KCNQ2/Q3 channels was increased,the activation curve shifted to the depolarized potentials,and KCNQ2/Q3 channel Ⅰ-Ⅴ curve slope was decreased in 10 mmol/L chloroprocaine group (P ＜ 0.05).Conclusion Chloroprocaine concentration-dependently suppresses KCNQ2/Q3 channel currents in HEK2936 cells.The KCNQ2/Q3 channel is closed in advance due to KCNQ2/Q3 channel opening delay induced by chloroprocaine thus decreasing the activity of KCNQ2/Q3 channels.