Exercise training improves cardiac function and attenuates insulin resistance in Dahl salt-sensitive rats

Abstract

BACKGROUND: The development of heart failure (HF) secondary to hypertension is a complex process related to a series of physiological and molecular factors including glucose dysregulation. The overall objective of this study was to investigate whether exercise training could improve cardiac function and insulin resistance in a rat model of hypertensive HF. METHODS: Seven week old Dahl salt-sensitive rats received either 8% NaCl (n=30) or 0.3% NaCl (n=18) diet. After a 5-week diet, animals were randomly assigned to exercise training (treadmill running at 18m/min, 5% inclination for 60min, 5days/week) or kept sedentary for 6 additional weeks. 2D echocardiography was used to calculate left ventricular (LV) dimensions, volumes and global functional parameters. LV global deformation parameters were measured with speckle tracking echocardiography. Insulin resistance was assessed using 1h oral glucose tolerance testing. RESULTS: High salt diet led to cardiac hypertrophy and HF, characterized by increased wall thicknesses and LV volumes as well as reduced deformation parameters. In addition, high salt diet was associated with the development of insulin resistance. Exercise training improved cardiac function, reduced the extent of interstitial fibrosis and reduced insulin levels 60min post-glucose administration. CONCLUSIONS: Even if not fully reversed, exercise training in HF animals improved cardiac function and insulin resistance. Adjusted modalities of exercise training might offer new insights not only as a preventive strategy, but also as a treatment for HF patients.