Age-related digoxin-verapamil interactions in the adult rat.

We have previously described a method for inducing atrial ectopic tachycardia (AET) in the anesthetized adult rat using digoxin, 30 mg/kg s.c. In this study, we used this model to study digoxin-verapamil interactions in young and older male rats and have found age-related differences in their responses to digoxin alone and to digoxin-verapamil interactions as well. Overall, 90% of the animals of both groups combined that developed AET, developed a ventricular proarrhythmic response to verapamil. Thus, this model might broaden the pre-clinical evaluation of anti-arrhythmic agents and predict which drugs are most likely to have a proarrhythmic effect.