Effects of Propafenone, Amiodarone and Dflthiazem on the potassium channel of c-Type Kvl. 4△N

Abstract

Objective To study the effects of the antiarrhythmic drugs of propafenone, amiodarone and difthiazem on c-type Kvl. 4 channels in Xenopus laevis oocytes with two-electrode voltage-clamp technique. Methods Defolliculated oocytes （stage V - VI） had transcribed cRNAs of ferret Kvl. 4△N channels injected. The oocytes were continuously perfused with control solution or propafenone, amiodarone and dilthiazem under monitoring of software of Clampfit v 9. 0. Results All of the three drugs blocked ferret Kvl. 4△N channel in voltage-, frequency- and concentration-dependent manners. The values of IC50 （50% inhibiting concentration ） of propafenone, amiodarone and dilthiazem were （ 103.4±2. 2 ） μmol/L, （501.22± 5.9） μmol/L and （353.62 ± 9.9） μmot/L, respectively. The currents under the actions of propafenone , amiodarone and dilthiazem were decreased to 41%, 32% and 21% of control group, respectively. Propafenone （100μmol/L）, Amiodarone （500μmol/L）, dilthiazem （350μmol/L） inhibited currents to （54. 6 ±1.9 ） %, （ 46. 3 ± 3.5 ） % , （ 52. 8 ± 2. 8 ） % of control group in voltage-dependent blockage. Conclusions The results suggested that all the three drugs blocked the kvl. 4△N channel in the open state. The three drugs block the kvl. 4△N channel maybe had the similiar effects in some respects, but each had its unique characteristics. Key words: Kvl. 4 channel; C-type inactivation; Propafenone ; Amiodarone ; Dilthiazem; Electrophysiology