EARLY INCIDENCE OF ADRIAMYCIN TREATMENT ON CARDIAC PARAMETERS IN THE RAT

To evaluate the early effect of low doses of adriamycin (ADR) on cardi ac parameters, male Wistar rats were injected with ADR (1 mg.kg(-1).da y(-1)) or saline for 10 days. Seven days later, T-1 and T-2 relaxation times were determined in left ventricular (LV) free wall, septum, and thigh muscle samples. In another experiment, performed on isolated wo rking hearts of rats pretreated with ADR, LV performance was determine d along with an index of myocardial lipid peroxidation in this tissue. Lipid peroxidation was enhanced (p <0.05). This change was not associ ated with a reduced LV performance, since both aortic and cardiac flow s measured in working heart preparations were similar between control and treated rats. However, the coronary flow was significantly reduced (control group, 21 +/- 1 mL.min(-1).g(-1), ADR group, 15 +/- 1 mL.min (-1).g(-1); p < 0.001). T-1 increased in the LV free wall (665 +/- 3 t o 696 +/- 5 ms, p < 0.001) and in the septum (657 +/- 3 to 696 +/- 5 m s, p < 0.01), while T-2 increased only in the LV free wall (50.8 +/- 0 .9 to 53.1 +/- 0.6 ms, p < 0.05). Myocardial water content was also si gnificantly increased. No modification was observed in the thigh muscl e samples. Thus, modifications of T-1 and T-2 relaxation times followi ng ADR treatment are associated with biochemical changes implicating l ipid peroxidation. These changes in relaxation times appeared earlier than hemodynamic deterioration and could provide a basis for the appli cation of proton nuclear magnetic resonance imaging in the early detec tion of cardiac ADR toxicity.