Kapelko, V. I., Veksler, V. L, Gorina, M. S. and Golikov, M. A.: Calcium-dependent changes of the myocardial contractile function at chronic adriamycin treatment. Acta physiol, pol., 1988, 39 (3): 106-174. The contractile function of hearts and atria isolated from rats treated with adriamycin (ADM, total cumulative dose 16-20 mg/kg for 8-10 weeks) was moderately lower as compared to control ipreparations. However, the former exhibited a relatively higher positive inotropic response to an elevation of Ca⁺⁺ concentration in the perfusate of isolated hearts or paired pulse stimulation of atria so that maximally attainable values were similar in both groups. On the contrary, the depression of ADM-treated atrial contractile amplitude became even more prominent at moderate increase in stimulation rate and was associated with the apparent incomplete re- laxation. Chemically skinned fibers from ADM-treated hearts began to develop force at lower Ca⁺⁺ concentration and exhibited higher Ca⁺⁺ - -sensitdvity in pCa range 5.8-5.4. Results suggest that long-term ADM- -treatment may he associated with a functional deficiency of Ca⁺⁺ -trans- porting mechanisms in myocardial cells which may contribute to the depression of the cardiac contractile function.