Click on image to view larger version.

Figure 4 Telomere Length in Sedentary and Running Mice

(A) Telomere length of blood leukocytes in 3-week (wk)-, 6-month (mo)-, and 18-month-old sedentary mice and in mice with running wheels exercising for 6 months (run) determined by Flow-fluorescence in-situ hybridization (FISH) assays displayed in base pairs (bp) and expressed as box plots, indicating the median as horizontal lines and boxes as 25th and 75th percentiles as well as whiskers as 10th and 90th percentiles. ***p < 0.001 versus 3 wk and 6 mo, n = 8 to 12 per group. (B) Effects of 6 months of running wheel exercise compared with 3-week-, 6-month, and 18-month-old sedentary condition on murine cardiomyocyte telomere length as determined by quantitative (Q) FISH. Results are presented in mean telomere fluorescence units per high-power field as box plots. ***p < 0.001 versus every other condition (n = 4 per condition, with each n consisting of 2 myocardial sections and 3 high-power fields captured from each section). (C) Exemplary images of murine cardiomyocyte telomeres (QFISH, red dots) and the corresponding nuclei (4,'6-Diamidino-2-phenylindoldihydrochloride [DAPI], blue) for 3-week- and 18-month-old sedentary condition, 40x magnification. (D) Quantification (n = 8) and representative fluorescence microscopic image of Ki-67–positive nuclei (red) in cardiomyocytes identified by alpha-sarcomeric actin coimmunostaining (green) after 3 weeks of voluntary running. Nuclei are stained blue by DAPI. 100x magnification. *p < 0.05. LV = left ventricle.