Electrophysiological actions of flecainide in normal and infarcted canine Purkinje fibers.
The electrophysiological effects of flecainide, 0.1, 0.5 and 1.0 mg/l, on action potential characteristics were examined in normal Purkinje fibers and Purkinje fibers surviving infarction, at stimulation cycle lengths of 1000 and 300 ms. Overshoot, amplitude and dV/dtmax were reduced significantly in a dose-dependent manner by flecainide in both normal Purkinje fibers and Purkinje fibers surviving infarction. Action potential duration was shortened by flecainide to a greater extent: at the cycle length of 1000 ms compared to 300 ms; at 50% repolarization compared to 90%; and in normal preparations compared to infarcted preparations. Activation time was increased by flecainide in a dose-dependent manner in both types of preparations. This effect was enhanced at the shorter cycle length. In both normal and infarcted preparations, flecainide shortened the ERP of those having a longer initial ERP and lengthened those with a shorter ERP. This effect was significant only at the stimulation cycle length of 1000 ms. This study indicates that flecainide has properties unique and different from traditional antiarrhythmic drugs.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004285:Dogs; D004594:Electrophysiology; D005260:Female; D005424:Flecainide; D006329:Heart Conduction System / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D008839:Microelectrodes; D009203:Myocardial Infarction / Q000503:physiopathology*; D010880:Piperidines / Q000494:pharmacology*; D011690:Purkinje Fibers / Q000187:drug effects*
D010880:Piperidines; D005424:Flecainide