Eighteen-month-old SHR were evaluated to identify clinical features of heart failure such as tachypnea/labored respiration and weight loss. After heart failure was detected, rats were subjected to echocardiogram and euthanized. Age-matched normotensive Wistar-Kyoto (WKY) rats were used as controls. Myostatin and follistatin protein expression was assessed by Western blotting. Statistical analysis was performed by Student's t test.
All SHR (n = 8) presented right ventricular hypertrophy and five had lung congestion. SHR had left chambers hypertrophy and dilation (left atrial diameter: WKY 5.73 ± 0.59; SHR 7.28 ± 1.17 mm; p = 0.004; left ventricular (LV) diastolic diameter/body weight ratio: WKY 19.6 ± 3.1; SHR 27.7 ± 4.7 mm/kg; p = 0.001), and LV systolic dysfunction (midwall fractional shortening: WKY 34.9 ± 3.31; SHR 24.8 ± 3.20%; p = 0.003). Myocyte diameter (WKY 23.1 ± 1.50, SHR 25.5 ± 1.33 μm; p = 0.004) and myocardial interstitial collagen fraction (WKY 4.86 ± 0.01; SHR 8.36 ± 0.02%; p < 0.001) were increased in the SHR. Myostatin (WKY 1.00 ± 0.16; SHR 0.77 ± 0.23 arbitrary units; p = 0.035) and follistatin (WKY 1.00 ± 0.35; SHR 0.49 ± 0.18 arbitrary units; p = 0.002) expression was lower in SHR. Myostatin and follistatin expression negatively correlated with LV diastolic diameter-to-body weight ratio and LV systolic diameter, and positively correlated with midwall fractional shortening.
Myostatin and follistatin protein expression is reduced in the long-term hypertrophied myocardium from spontaneously hypertensive rats with heart failure.