Anti-arrhythmic effects of sophoridine and oxysophoridine.

Aim: To compare the effects of oxysophoridine (Oxy) and sophoridine (Sop) on experimental arrhythmias and myocardial physiologic properties.

Methods: Arrhythmias were induced by drugs and myocardial ischemia. Physiologic properties were determined on isolated heart atria.

Results: Oxy 500 mg.kg-1 (1/6 LD50) decreased the incidence of ventricular arrhythmias induced by aconitine (P < 0.01), increased the threshold dose of ouabain-induced ventricular premature (VP, P < 0.05), ventricular tachycardia (VT, P < 0.05), ventricular fibrillation (VF, P < 0.01), and cardiac arrest, (P < 0.01). After i.v. Oxy 500 mg.kg-1 into the rats with ligation of left anterior descending coronary artery, the total numbers of ectopic beats were decreased (P < 0.05), the incidence of VF was lowered, and the duration of VT was shortened (P < 0.01). Oxy 250 mg.kg-1 (1/13 LD50) i.v. shortened the duration of arrhythmias induced by BaCl2 (P < 0.01) and delayed the onset of arrhythmias induced by chloroform-epinephrine (P < 0.05). Oxy produced dose-dependent positive inotropic effects in the isolated left atrial of guinea pigs, increased the concentration of epinephrine to elicit automaticity in left atria, decreased slightly the excitability, and prolonged the functional refractory period. Sop produced the similar effects on arrhythmias as Oxy.

Conclusion: Oxy produced the similar anti-arrhythmic effects as Sop did at the equivalent effective dose.