title: Electrophysiological effects of the optical isomers of disopyramide and quinidine in the dog. Dependence on stereochemistry.
abstract: We studied the electrophysiological effects of the optical isomers of disopyramide and quinidine on canine cardiac Purkinje fibers. Conventional microelectrode techniques were employed to study the effects of racemic disopyramide, (+)-disopyramide, (-)-disopyramide, quinidine, and quinine. Racemic disopyramide, (+)-disopyramide, and quinidine prolonged action potential duration (APD) measured at 90% repolarization. In contrast, (-)-disopyramide and quinine shortened APD. These directionally opposite effects on repolarization were observed throughout 60 minutes exposure to drug and were concentration-dependent. All five components reduced dV/dt of phase 0, increased conduction time, and increased the current requirement for all-or-none depolarization. The effects of all five compounds on dV/dt, conduction time, and current requirements were time- and concentration-dependent. Our results indicate that the stereochemical configurations of disopyramide and quinidine determine their effects on repolarization of cardiac Purkinje fibers.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D004206:Disopyramide / Q000494:pharmacology*; D004285:Dogs; D004594:Electrophysiology; D005260:Female; D008297:Male; D011690:Purkinje Fibers / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology*; D011802:Quinidine / Q000494:pharmacology*; D011803:Quinine / Q000494:pharmacology; D013237:Stereoisomerism; D013997:Time Factors
chemical_list: D011725:Pyridines; D011803:Quinine; D004206:Disopyramide; D011802:Quinidine