Figure 5.

Cardiac-specific PP2Cm KO abolished the cardioprotective effects of exercise. (A). The control (Ppm1k^flox/flox) and KO (Ppm1k^CKO) mice were subjected to MI after an 8-week exercise intervention to test whether PP2Cm upregulation contributes to exercise-induced cardioprotection. (B). Exercise preconditioning showed no significant effects on body weight in both control and KO mice with MI. (C). Exercise preconditioning increased cardiac systolic function as detected by echocardiography in control but not KO mice with MI. (D,E). Heart weight (D) and heart weight–body weight ratio (E) in mice subjected to MI in control and KO mice. (F). Cardiac structure and fibrosis as detected by Masson staining in mice subjected to MI in control and KO mice. The blue staining indicates collagen and fibrosis. (G). Exercise preconditioning increased cardiac capillary density (the ischemic territory near the non-infarct area) as detected by CD31 immunofluorescence in control but not KO mice with MI. (H). Exercise preconditioning attenuated cardiac apoptosis as detected by TUNEL staining in control but not KO mice with MI. (I). Caspase 3 and cleaved caspase 3 contents in control and KO mice (n = 4). Values are presented as mean ± SEM. n = 6. * p < 0.05; ** p < 0.01; *** p < 0.001.