FASEB journal : official publication of the Federation of American Societies for Experimental Biology
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Aging is characterized by loss of myocytes, remodeling, and impaired contractile function in the heart. The rate of programmed cell death, or "apoptosis," in the left ventricle increases with age, and contributes to a 30% reduction in myocytes. Aging may preferentially target the Bcl-2 pathway of apoptosis in the heart. ⋯ Exercise training significantly attenuated age-induced increases of apoptosis in the left ventricle, as indicated by lower DNA fragmentation, TUNEL-positive staining, and caspase-3 cleavage, when compared with left ventricles from the age-matched sedentary group. Further, exercise training in the aging reduced caspase-9 levels and Bax/Bcl-2 ratio by lowering Bax protein expression while increasing Bcl-2 levels. These are the first data to demonstrate protective effects of endurance exercise training against elevated apoptosis and remodeling in the aging heart.