Combined cardiovascular effects of ovariectomy and high-intensity interval training in female spontaneously hypertensive rats.

Hypertensive postmenopausal women are more likely to develop adverse cardiac remodelling and respond less effectively to drug treatment than men. High intensity interval exercise (HIIE) is a non-pharmacological strategy for the treatment of hypertension, however, the effectiveness in women remains uncertain. This study was designed to evaluate (1) effects of HIIE training upon morphological and functional markers of cardiovascular health in female SHR and (2) to determine whether the hormonal shift induced by ovariectomy could influence cardiovascular responses to HIIE. 36 SHR were randomly assigned to 4 groups: ovariectomised sedentary, ovariectomised trained, sham-operated sedentary and sham-operated trained. The trained rats performed HIIE 5 days/week for 8 weeks. Blood pressure and echocardiographic measurements were performed before and after training in animals. Cardiac response to β-adrenergic stimulation and the expression of calcium regulatory proteins and estrogen receptors in heart samples were assessed. Endothelium-dependent vasorelaxation in response to acetylcholine was evaluated in aortic rings as well as the expression of nitric oxide synthase isoforms (eNOS and P-eNOS) by western blotting. In both groups of trained SHR, HIIE induced eccentric cardiac remodelling with greater inotropic and chronotropic effects, as well as an increase in SERCA and β1AR expression. However, although the trained rats showed improved endothelial function and expression of eNOS and P-eNOS in the aorta, there was no demonstrated effect on blood pressure. Additionally, the responses to HIIE training were not affected by ovariectomy. This work highlights the importance of assessing the cardiovascular efficacy and safety of different exercise modalities in women.