Background: We evaluated angiogenic responses in the left ventricular muscle and aerobic capacity according to exercise type (aerobic, resistance, combined) in aged rats.
Methods: In total, 24 male Sprague-Dawley rats (100 weeks old) were used. To investigate the effect of regular training, the rats were divided into non-exercise (NE), aerobic exercise (AE), resistance exercise (RE), and combined exercise (CE) groups (six rats per group). Regular training tailored to each exercise type was performed for 8 weeks (five times a week, 1 h per day). After 8 weeks of training, aerobic capacity was evaluated by a treadmill running test. Left ventricular muscle tissue was collected and the protein levels of angiogenesis indicators (eNOS, HIF-1α, PGC-1α, VEGF, FLK-1, Ang-1, Ang-2) were analyzed by Western blotting. Capillaries were observed by immunohistochemical staining for CD31.
Results: Body weight, heart weight, and heart/body weight ratio showed no difference among the groups. The AE and CE groups showed higher treadmill running capacity than the NE and RE groups. The eNOS, VEGF, HIF-1α, PGC-1α, and Ang-2 protein levels were significantly higher in the AE than NE group. The PGC-1α and FLK-1 protein levels were significantly higher in the RE than NE group. In addition, in the CE group, the eNOS, FLK-1, and PGC-1α protein levels were significantly higher than in the NE group. Expression of CD31 in cardiac tissue was higher in the AE and CE groups than in the other groups.
Conclusions: Taken together, the results suggest that regular exercise training, irrespective of exercise type, might improve cardiovascular function by inducing angiogenic responses in the aged myocardium; however, AE may be the most effective.
Keywords: Aging; Angiogenesis; Capillary; Exercise training; Left ventricular muscle.
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