Moderate exercise training does not worsen left ventricle remodeling and function in untreated severe hypertensive rats

Abstract

Exercise training and hypertension induced cardiac hypertrophy but modulate differently left ventricle (LV) function. This study set out to evaluate cardiac adaptations induced by moderate exercise training in normotensive and untreated severe hypertensive rats. Four groups of animals were studied: normotensive (Ctl) and severe hypertensive (HT) Wistar rats were assigned to be sedentary (Sed) or perform a moderate exercise training (Ex) over a 10-wk period. Severe hypertension was induced in rat by a two-kidney, one-clip model. At the end of the training period, hemodynamic parameters and LV morphology and function were assessed using catheterism and conventional pulsed Doppler echocardiography. LV histology was performed to study fibrosis infiltrations. Severe hypertension increased systolic blood pressure to 202 ± 9 mmHg and induced pathological hypertrophy (LV hypertrophy index was 0.34 ± 0.02 vs. 0.44 ± 0.02 in Ctl-Sed and HT-Sed groups, respectively) with LV relaxation alteration (early-to-atrial wave ratio = 2.02 ± 0.11 vs. 1.63 ± 0.12). Blood pressure was not altered by exercise training, but arterial stiffness was reduced in trained hypertensive rats (pulse pressure was 75 ± 7 vs. 62 ± 3 mmHg in HT-Sed and HT-Ex groups, respectively). Exercise training induced eccentric hypertrophy in both Ex groups by increasing LV cavity without alteration of LV systolic function. However, LV hypertrophy index was significantly decreased in normotensive rats only (0.34 ± 0.02 vs. 0.30 ± 0.02 in Ctl-Sed and Ctl-Ex groups, respectively). Moreover, exercise training improved LV passive filling in Ctl-Ex rats but not in Ht-Ex rats. In this study, exercise training did not reduce blood pressure and induced an additional physiological hypertrophy in untreated HT rats, which was slightly blunted when compared with Ctl rats. However, cardiac function was not worsened by exercise training.