Post-Myocardial Infarction Exercise Training Induces Angiogenesis in the heart

Cardiac angiogenesis after myocardial infarction (MI) is critical to the development of compensatory hypertrophy in the viable myocardium; however, compelling evidence suggests that post-MI cardiac angiogenesis is inadequate, and may promote the transition from adaptive cardiac hypertrophy to left ventricular (LV) dilation and dysfunction. Exercise, through increased vascular shear stress, potentiates a powerful antigenic stimulus. We investigated whether exercise could promote cardiac angiogenesis in post-MI rats. MI was surgically induced on 7-wk-old Sprague-Dawley rats by ligation of the coronary artery. The survivors were assigned to 3 groups (n=10/group): Sham (no MI, no exercise), MISed (MI, no exercise), and MIEx (MI + exercise). Treadmill exercise training began 1-wk post-MI and lasted for 8-wks. Cardiac tissue was harvested at the end of the experiment and capillary density was assessed using CD- 31 staining. Our results indicated that left ventricular (LV) capillary density (counts/mm2) of Sham and MIEx groups were significantly higher compared to the MISed group (1280 ± 66 counts/mm2, 950 ± 47, 610 ± 44, respectively, p < 0.05). In the septum, capillary density was also higher in the MIEx group compared to MISed (1220 ± 54 vs. 890 ± 43 counts/mm2). Conclusion: Our data indicate that post- MI exercise training at a moderate intensity significantly increases cardiac angiogenesis, which in turn may attribute to the improvement in morbidity and mortality produced by exercise training in patients with MI. Keywords: myocardial infarction; exercise training; angiogenesis; animal model