Daunomycin inhibits the uptake of adenine, amino acids, and glucose into cardiac myocytes.

Daunomycin and adriamycin are widely used antitumor agents which induce dose-dependent cardiotoxicity. The mechanisms by which daunomycin causes cardiotoxicity have been investigated in neonatal rat cardiac myocytes maintained in tissue culture. Daunomycin inhibited the uptake of adenine, amino acids, and deoxyglucose in a dose-dependent fashion. The uptake of both adenine and methionine was inhibited without any delay while the glucose uptake (deoxyglucose) was inhibited after a delay of 2 hr. Since daunomycin affected the uptake of both adenine and amino acids without any delay and since daunomycin did not affect the incorporation of adenine into nucleotide and amino acids into proteins once these were transported into the cell, it is possible the daunomycin exerted these effects by acting directly on the cell membrane. Thus, one of the early toxic manifestations of anthracycline antibiotics may be on the transport of nutrients such as amino acids, glucose, and adenine.