Ketanserin inhibits digoxin-induced arrhythmias in the anaesthetized guinea-pig

Digoxin inhibits the membrane-bound ATPase enzyme, resulting in a rise in i ntracellular sodium and activated outward potassium current, predisposing t o arrhythmias. In this study, the effect of ketanserin, thought to block ou tward potassium currents, was investigated on digoxin-induced arrhythmias. Twenty-four guinea-pigs were studied in four groups (control, ketanserin 0. 5 mg/kg, ketanserin 1 mg:kg, ketanserin 2 mg/kg). Under pentobarbital anaes thesia (40 mg/kg), 15 min after injection of saline or ketanserin, digoxin (0.6 mg/kg) was administered through the jugular vein. Carotid artery blood pressure and electrocardiogram (ECG) were recorded. The rime for the onset of the first arrhythmia and incidence of ventricular tachycardia (VT), ven tricular fibrillation (VF); and premature ventricular contraction (PVC) wer e determined. Arrhythmias were scored according to the MacLeod scale. Ketan serin produced minor haemodynamic effects and lacked, by itself, arrhythmog enic effects at the doses studied. However, it increased the time for the o nset of the first digoxin-induced arrhythmia and decreased the incidence of VT, VF and PVC. We conclude that ketanserin inhibits digoxin-induced arrhy thmias in guinea-pigs. (C) 1999 Editions scientifiques et medicales Elsevie r SAS.