Figure 1. Aged mice show cardiac hypertrophic response. (A) Heart weight to tibia length (HW/TL) ratio of 4-month-old (Young) and 24-month-old (Old) mice. Values are mean ± SE, n = 8-10. (B) Echocardiographic measurements of fractional shortening in young and old mice. Values are mean ± SE, n = 8-10. (C) Representative sections of hearts stained with Masson's trichrome to detect fibrosis (blue); scale bars, 20 μm. (D) Quantification of cardiac fibrosis in young and old mice. Mean ± SE, n = 6. (E) Expression levels of βMHC and ANF mRNA in young and old mice, mean ± SE, n = 6 mice. (F) Heart lysates of young and old mice were subjected to immunoblotting using indicated antibodies. Representative blots of three different mice in each group are shown, n = 6. (Quantification of blots is given in Supplementary Figure 3A–3E).