Effect of antiarrhythmic drugs on the cycle length-dependent action potential duration in dog Purkinje and ventricular muscle fibers.
We examined the steady-state action potential duration (APD) within a wide range of cycle lengths (CL) in cardiac dog Purkinje (P) and ventricular (V) muscle fibers in the presence of: lidocaine (L) 4 and 8 micrograms/ml, mexiletine (M) 4 and 8 micrograms/ml, flecainide (F) 1 and 4 micrograms/ml, disopyramide (D) 3.1 and 10 micrograms/ml, quinidine (Q) 2.5, 5, and 10 micrograms/ml, bretylium tosylate (B) 5 and 10 micrograms/ml, and sotalol (S) 5 micrograms/ml. In the P fibers, all drugs except for B and S shortened plateau duration, increased slope of phase 2 and decreased slope of phase 3 repolarization, and either shortened (L, M, Q, F) or prolonged (D) APD. B and S lengthened APD and did not change significantly the slopes of phase 2 and 3 of repolarization. Each drug altered the relation between APD and Cl according to one of the following three patterns: (a) L, M, Q, and F shortened APD more at long than at short CL; (b) D lengthened APD more at short than at long CL; (c) B and S lengthened APD more at long that at short CL. In the V fibers, APD was lengthened by F, Q, and B, and shortened by L and M. The drug-induced changes in the relation between APD and CL were as in the P fibers. The results suggest that the drug-induced changes in the relation between APD and CL can be predicted from the drug effects on the course of repolarization.
A
A
Varro
Y
Y
Nakaya
V
V
Elharrar
B
B
Surawicz
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D004285:Dogs; D004594:Electrophysiology; D005260:Female; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D006329:Heart Conduction System / Q000187:drug effects*; D006352:Heart Ventricles / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D011690:Purkinje Fibers / Q000187:drug effects* / Q000502:physiology; D016276:Ventricular Function
D000889:Anti-Arrhythmia Agents