Effects of lidocaine, phenytoin and quinidine on the ischemic canine myocardium.
The effects of therapeutic concentrations of lidocaine, quinidine and phenytoin on the electrograms and excitability of ischemic canine myocardium were investigated. The threshold stimulation current was determined as the minimum current necessary to drive the ventricles at 300 msec intervals. Administration of the drugs did not change the threshold stimulation current of the control myocardium, but lidocaine (P less than 0.002), quinidine (P less than 0.01) and phenytoin (P less than 0.05) all markedly increased the threshold stimulation current of the ischemic tissue. The effects on the electrograms were small but consistent with current electrophysiological knowledge. This selective depression of the electrical activity of the ischemic tissue may form an important mechanism of action of these antiarrhythmic agents. However, this same effect may under certain conditions precipitate serious arrhythmias.
D000818:Animals; D001794:Blood Pressure; D003327:Coronary Disease / Q000188:drug therapy / Q000503:physiopathology*; D004285:Dogs; D004576:Electromyography; D006339:Heart Rate / Q000187:drug effects; D008012:Lidocaine / Q000494:pharmacology* / Q000627:therapeutic use; D010672:Phenytoin / Q000494:pharmacology* / Q000627:therapeutic use; D011802:Quinidine / Q000494:pharmacology* / Q000627:therapeutic use; D013268:Stimulation, Chemical
D010672:Phenytoin; D008012:Lidocaine; D011802:Quinidine