Influence of myocardial mechanical activity and coronary blood flow on myocardial digoxin uptake

The myocardial content of digoxin 60 min after intravenous administration in open-chest dogs correlated with heart rate controlled in individual dogs between 64 and 215 beats/min. In other dogs, increasing right ventricular mechanical work by constriction of the pulmonary artery resulted in greater right ventricular digoxin uptake. Increase in myocardial blood flow per se could not explain these findings since, in further dogs, increasing regional myocardial blood flow by adenosine infusion did not much affect digoxin uptake. Active uptake of cardiac glycosides is probably influenced by myocardial mechanical and metabolic activity.