Anti-arrhythmic effects of guan-fu base a

Guan-fu base A is a new alkaloid isolated from the tuber of Aconitum coreanum in our institute. Pretreatment of rats with guan-fu base A 20 0r 30 mg/kg iv significantly reduced the incidence of ventricular fibrillation induced by CaC12 130 mg/kg and reduced the mortality as well. This alkaloid. iv 2.5-20 mg/kg 2 min previously in anesthetized rats, increased the amount of beiwutine necessary to produce cardiac arrhythmias. Guan-fu base A 30 mg/kg iv increased markedly the ouabain doses to cause ventricular premature beats, ventricular fibrillation and cardiac arrest in anesthetized guinea pigs. The ventricular fibrillation threshold to electrical stimulation was elevated in anesthetized cats by given guan-fu base A 2-8 mg/kg iv. Guan-fu base A produced a bradycardia even after vagotomy and did not block the isoproterenol-induced achycardia and hypotension in cats. In Langendorffis guinea pig hearts, guan-fu base A (4 mg) caused a 32% reduction of heart rate and a 27% reduction of coronary flow. a 33% diminution of the amplitude of cardiac contraction.