Effects of 6,7-dimethoxycoumarin on experimental arrhythmia

: By using the arrhythmic animal models, the effect of 6,7-dimethoxycoumarin (DMOC) on arrhythmia was investigated. The arrhythmia in anaesthetized rat were induced by iv aconitine 20 micrograms.kg-1 or CaCl2 5 mg.kg-1. The arrhythmia in anesthetized guinea pigs was induced by iv ouabain 3.6 micrograms.kg-1.min-1. Procainamide (PA) was used as a positive control. DMOC (33-500 mg.kg-1, ig) and PA (100-800 mg.kg-1, ig) in anaesthetized rats could delay the time of onset of arrhythmia induced by aconitine. The ED50 of DMOC and PA for postponing the occurrence of ventricular extrasystole (VE) were 88 mg.kg-1 (95% confidence interval was 43-165 mg.kg-1) and 183 mg.kg-1 (95% confidence interval was 109-304 mg.kg-1), respectively. The results suggested that the anti-arrhythmia potency of DMOC was higher than that of PA (P < 0.01).