SUBMAXIMAL, AEROBIC EXERCISE TRAINING EXACERBATES THE CARDIOMYOPATHY OF POSTWEANLING CU-DEPLETED RATS

To determine the dual effect of exercise training and copper depletion on myocardial function and ultrastructure, postweanling rats were eit her trained or sedentary while fed copper-adequate or copper-deficient diets for 8 wk. Rats developed characteristic myocardial subcellular degeneration and increased cardiac mitochondrial volume density when c opper depleted, despite lack of overt cardiac hypertrophy, hypertensio n, or anemia. Training combined with copper depletion induced mild lef t ventricular hypertrophy. Basal laminae appeared fractionated in area s at capillary-myocyte interface, with focal pericapillary and interst itial collagen accumulation, whereas overt fibrosis was absent or mini mal. Electrocardiograms revealed increased QRS wave and QT duration an d notching of QRS complex with copper depletion, consistent with intra ventricular conductance disturbances. The oxidative capacity of soleus muscle increased with training in copper-adequate rats, but was reduc ed with progressive copper depletion. These data suggest that copper d epletion and training are synergistic in effecting focal accumulation of collagen, with deleterious effect on exercise capacity.