Effects of Platelet‐Activating Factor Antagonists WEB 2086 and BN 50730 on Digoxin‐Induced Arrhythmias*

Effects of platelet-activating receptor antagonists WEB 2086 (1.0-30.0 mg.kg-1 intravenously) and BN 50730 (10.0 mg.kg-1 intravenously) alone or in combination with CGS 8515 (a specific 5-lipoxygenase inhibitor, 0.3 mg.kg-1 intravenously) and Dazmegrel (a thromboxane synthase inhibitor, 1.0 mg.kg-1.hr-1 intravenous infusion) on digoxin-induced arrhythmias were investigated in anaesthetised guinea-pigs. ECG, mean arterial blood pressure, heart rate and arrhythmias were recorded, starting 30 min. before digoxin administration and continuing for 60 min. afterwards. WEB 2086 (10.0 mg.kg-1 intravenously) reduced the mortality rate and arrhythmia score significantly compared to the control values. However, in combination with CGS 8515, it did not affect the mortality rate. BN 50730 (10.0 mg.kg-1) reduced the incidence of ventricular fibrillation and also arrhythmia score. BN 50730 in combination with Dazmegrel was reduced the arrhythmia score, incidence of ventricular fibrillation and mortality rate significantly, compared to control values. Digoxin-induced acute rise in mean arterial blood pressure was not affected by any of drug treatment except WEB 2086 (10.0 mg.kg-1) in combination with CGS 8515. Heart rate values did not differ between groups. However, pressure-rate index was reduced by WEB 2086 alone or in combination with CGS 8615. Results showed that although two different platelet-activating factor antagonists have different effects on the incidence of ventricular fibrillation and mortality, they improved the digoxin-induced arrhythmias when they were used either separately or in combination with CGS 8515 or Dazmegrel by implicating that platelet-activating factor has a role on digoxin-induced arrhythmias.