[Effects of antiarrhythmic agents on ventricular arrhythmias following myocardial infarct induced with glass beads in dogs (author's transl)]

Ventricular arrhythmias due to myocardial infarct were produced in 14 dogs, and the antiarrhytmic effects of quinidine (Qd), lidocaine (Lid), aprindine (Apr), and dl-propranolol (dl-Prop) were investigated. While recording the blood pressure and lead II ECG, a coronary cannula was inserted into a coronary orifice via the left carotid artery and a glass bead (diameter, 1.5 mm) was flushed into the left coronary artery. Beads were found at the descending branches in 12 and circumflex branches in 2 out of 14 gods, at autopsy. Using a telemetry system to record the lead II ECG of conscious, non-restricted dogs, the antiarrhythmic effects of Qd, Lid, Apr, and dl-Prop on ventricular arrhythmias 24 hours after coronary occlusion were compared. Apr and dl-Prop were about three times more potent than Qd and Lid. Although the durations of the antiarrhythmic effects of Apr, Lid, and dl-Prop were 20 to 30 min, that of Qd lasted longer. Since stable ventricular arrhythmias can be obtained by surgical intervention and the antiarrhythmic effects of standard compounds with glass beads can be used to study antiarrhythmic effects.

Some pharmacological studies on the cardiotonic effects of furanosteroidal glycosides

Cardiotonic effects and cardiotoxicities of three furanosteroidal glycosides were compared with those of standard cardiac glycosides (digitoxin, gitoxin, etc.). Furanosteroidal glycosides showed positive inotropic effects in both isolated guinea-pig atria and rabbit hearts. The positive inotropic effect of 17beta-(3-furyl)-5beta,14beta-androstane-3beta,14,16beta-triol-3-bisdigitoxoside(FGBD) corresponded to that of digitoxin in isolated guinea-pig atria and frog hearts. Intravenous and oral administration of FGBD and 17beta-(3-furyl)-5beta,14beta-androstane-3beta,14,16beta-triol-3-tridigitoxoside(FGTD) in higher doses induced cardiac arrest after vomiting, bradycardia, ventricular rhythm, and ventricular fibrillation in pigeons and cats. Comparison of lethal doses between intravenous and oral administration of cardiac glycosides in pigeons and cats suggested that gastrointestinal absorption of FGBD and FGTD is inferior to that of digitoxin but superior to that of gitoxigenin bisdigitoxoside and gitoxin. Cardiotonic effects of furanosteroidal glycosides were confirmed in isolated guinea-pig, rabbit and frog hearts.

Antiarrhythmic effect of aprindine on several types of ventricular arrhythmias

The antiarrhythmic effect of aprindine was compared with those of lidocaine and propranolol on several ventricular arrhythmias-epinephrine arrhythmias in cats, ouabain arrhythmias in cats and guinea pigs, ischemic ventricular arrhythmias in coronary-ligated Beagle dogs. Antiarrhythmic effects of aprindine and lidocaine were observed both in ouagain and ischemic arrhythmias, but not in epinephrine arrhythmias. While propranolol had a strong antiarrhythmic effect against epinephrine and ouabain arrhythmias, it did not increase sinus beats in ischemic arrhythmias. Marked anti-arrhythmic effects of aprindine in ischemic arrhythmias were observed in dogs using either single intravenous administration (4 mg/kg) or intravenous infusion (200 mug/kg/min, 2 mg/kg). Antiarrhythmic activity of aprindine is considered to be about twice as strong as that of lidocaine, but lidocaine is less toxic in experimental animals.