Cardiac troponin T alterations in myocardium and serum of rats after stressful, prolonged intense exercise

1 Division of Kinesiology, School of Kinesiology and Leisure Studies, University of Minnesota, Minneapolis 55455; 2 Department of Laboratory Medicine and Pathology, School of Medicine, University of Minnesota, Hennepin County Medical Center, Minneapolis 55404; and 3 Jesse E. Edwards Registry of Cardiovascular Disease, St. Paul, Minnesota 55102 The goal of this study was to determine whether the stress of forced exercise would result in injury to the myocardium. Male rats with 8% of body weight attached to the tail were forced to swim 3.5 h (3.5S), forced to swim 5 h (5S), or pretrained for 8 days and then forced to swim 5 h (T5S). Rats were killed immediately after they swam (0 h PS) and at 3 h (3 h PS), 24 h (24 h PS), and 48 h after they swam (48 h PS). Tissue homogenates of the left ventricle were analyzed by Western blot analysis for cardiac troponin T (cTnT). Serum cTnT was quantified by immunoassay. Results indicated that, in the 3.5S, 5S, and T5S groups, serum cTnT was significantly ( P