Figure 1. Rapamycin improves cardiac function and inhibits mTOR signaling in old hearts. Rapamycin treatment increased Ea/Aa (A) and reduced MPI (B) but did not alter fractional shortening (FS; C). n=3-7/group. * p<0.05 compared to 0 week of corresponding diet. Dotted lines indicate young values. Regression with time was significant (p<0.05) for 1X and 3X Rapa Ea/Aa and 3X MPI. (D) 1X Rapa and 3X Rapa treatments showed similar reduction in normalized HW (HW/BW) in old hearts. * p<0.05 compared to old controls. (E) 1XRapamycin reversed cardiac hypertrophy at all time points in old hearts. (F-G) Rapamycin inhibited phosphorylation of S6 ribosomal protein (at S235/S236) at all time points. (H-K) Rapamycin reduced phosphorylation of PKCα (H) and S473-AKT (I) at all time points and T308-AKT (J) at 1- and 2-week. * p<0.05 compared to old controls (Ctrl). Data are represented as mean ± SEM.