ACUTE ANTIARRHYTHMIC EFFECTS OF INTRAVENOUSLY ADMINISTERED AMIODARONEON CANINE VENTRICULAR ARRHYTHMIA

We investigated antiarrhythmic effects of intravenously (i.v.) adminis tered amiodarone using four canine ventricular arrhythmia models. Bolu s injections of amiodarone 3 mg/kg suppressed epinephrine (EPI)-induce d arrhythmia and 5-mg/kg bolus injections of amiodarone suppressed dig italis- and two-stage coronary ligation-induced arrhythmia models, but the antiarrhythmic effects did not correlate with the amiodarone plas ma concentrations. The infusion of amiodarone 6.67 mg/kg/h did not pro long the QTc interval or produce antiarrhythmic effects in coronary li gation and reperfusion experiments. Amiodarone significantly decreased the mean blood pressure (MAP), and this effect lasted throughout the observation period. The results indicate that the antiarrhythmic effec ts of intravenously administered amiodarone may not be due to its clas s III action, but to other actions, such as class I, II, and IV action s.