Failing effect of digoxin on myocardial uptake of violamycin B1.

The effect of digoxin on both the negative inotropic action and the myocardial uptake of a new anthracycline antibiotic violamycin B1 has been studied in isolated guinea pig atria. In concentrations upto 2.0 X 10(-7) M/l digoxin did not prevent the negative inotropic effect of violamycin B1 caused by the concentrations of 0.7 and 5.0 X 10(-4) M/l. Corresponding to these findings, the uptake of violamycin B1 into the atrial tissue was not influenced by digoxin. However, violamycin B1 in the cardiotoxic concentration of 5.0 X 10(-4) M/l decreased the atrial uptake of digoxin. It is suggested that no competition seems to exist in myocardial uptake of anthracycline antibiotics and cardiac glycosides.