Figure 1. The cardiac reserve function decreases in aging mice. Echocardiography of the mice (A). Eject factor (EF, %) (B). Fractional shortening (FS, %) (C). The ratio of the early to late ventricular filling velocities (E/A ratio) (D). Left ventricular end-diastolic diameter (LVID(d), mm) (E). Left ventricular posterior wall end-diastolic thickness (LVPW(d), mm) (F). Left ventricular mass (LV mass, mg) (G). The ratio of the heart weight to total weight (H). Data are represented as mean +/- SEM. n = 6 per group. *P<0.05, **P<0.01 vs. 4 m. m=month.