Figure 2: Aging in F344XBN rats is associated with cardiomyocyte hypertrophy. A- Immunofluorescence labeling of dystrophin (FITC-green), actin staining (rhodamine phalloidin-red) and nuclei (DAPI-blue) in 6-, 27-, 30-, 33- and 36-month F344XBN rat heart cross sections. Magnification 400x. B- Average muscle fiber cross sectional area (μm2/fiber). Number of fibers measured for 6-, 27-, 30-, 33- and 36-month rats was 640, 423, 311, 235 and 190 respectively. Data are mean ± SE (n=3). * indicates significant difference from 6-month group, $ indicates significant difference from 27-month group, # indicates significant difference from 30- month group and @ indicates significant difference from 33-month group (P<0.05).