Dahl salt-sensitive (DS) rats were obtained from Harlan Sprague Dawley Laboratory at 5 weeks of age. At 6 weeks of age, physiologic cardiac hypertrophy was generated by a vigorous daily exercise regimen for 6 weeks (e group). The exercise protocol is based on those described previously with modifications (Wisloff U et al., 2001; Jin H et al., 1994). Rats were exercised daily for 6 weeks on a rodent treadmill (Exer-6M; Columbus Instruments). The exercise program consisted of three weeks of progressively strenuous exercise regimens; followed by three weeks of maintenance period, during which the rats were exercised at 16 m/min at a 5o incline for 90 minutes/day. All rats completed the exercise protocol. Pathological cardiac hypertrophy was generated by feeding a 6% NaCl diet to DS rats at 6 weeks of age (h group) (Inoko M et al., 1994). Control rats (c group) were age matched and sedentary DS rats fed normal rat chow. Read more at http://cardiogenomics.med.harvard.edu/groups/proj1/pages/rat_home.html Keywords = physiological hypertrophy, pathological hypertrophy, rat, heart failure, cardiomyopathy