Abstract 19155: Cardiac Stem Cell Activation and Ensuing Myogenesis and Angiogenesis Contribute to Cardiac Adaptation following Intensity-Controlled Exercise Training

The role of cardiac stem/progenitor cells (CSCs) in the cardiac adaptation to exercise stress is undefined. We evaluated whether treadmill exercise training at different intensities can stimulate c-kit positive (c-kitpos) CSCs and their differentiation into new myocytes and microvasculature in the adult rat myocardium. To this aim, 33 male Wistar rats (∼220g) were exercised at either a low (LI; 55–60% VO2 max) or high (HI; 85–90% VO2 max) intensity for 30 min/day, 4 days/wk for up to 4 wks on motorized treadmills. Eighteen untrained rats acted as age-matched sedentary controls (CTRL). To track myocardial cell proliferation, BrdU was administered (i.p.) twice daily. Immunohistochemical and confocal microscopy analysis of the left ventricle (LV) showed an increase (P<0.05) in average myocyte diameter in exercised animals compared to CTRL. In addition to larger (hypertrophied) myocytes, smaller BrdU (3.4±0.2% LI, 7.4±0.3% HI) and Ki67 (0.8±0.1% LI, 1.0±0.1% HI) positive myocytes were observed in the LV of ex...