[Effects on anthracycline antibiotics on ionic currents and contraction of frog atrial fibrils associated with Na+/Ca2+ exchange].

: The action of the anthracycline antibiotics rubomycin and its nitroxyl analogue ehoxyl(ruboxyl) at the concentration 100 mg/l was studied in the experiments, have been carried out with the isolated bundles of frog atrium using simultaneous registration of the ionic currents (or the active potentials) and the contraction. It has been shown, that rubomycin caused an action of potential shortening, membrane depolarization, increasing of the background outward current IKI, slowing of the muscle relaxation and the growth of the ionic contraction, associated with the Na/Ca exchange. Nitroxyl derivative of the rubomycin ruboxyl, exhibited small toxicity, did not change the ionic currents and the parameters of the mechanical activity. It is assumed, that cardiotoxicity of anthracyclines is in the great degree due to their ability to block the elimination of the Ca++ from the cell via the Na/Ca exchange, that results in the disturbance of the Ca-homeostasis of the cardiomyocyte and its calcium overload.