Exercise modulates the aortic renin-angiotensin system independently of estrogen therapy in ovariectomized hypertensive rats

Abstract

The renin-angiotensin-system is an important component of cardiovascular control and is up-regulated under various conditions, including hypertension and menopause. The aim of this study was to evaluate the effects of swimming training and estrogen therapy (ET) on angiotensin-II (ANG II)-induced vasoconstriction and angiotensin-(1-7) [ANG-(1-7)]-induced vasorelaxation in aortic rings from ovariectomized spontaneously hypertensive rats. Animals were divided into Sham (SH), Ovariectomized (OVX), Ovariectomized treated with E2 (OE2), Ovariectomized plus swimming (OSW) and Ovariectomized treated with E2 plus swimming (OE2+SW) groups. ET entailed the administration of 5μg of 17β-Estradiol three times per week. Swimming was undertaken for sixty minutes each day, five times per week. Both, training and ET were initiated seven days following ovariectomy. Forty-eight hours after the last treatment or training session, the animals’ systolic blood pressures were measured, and blood samples were collected to measure plasma ANG II and ANG-(1-7) levels via radioimmunoassay. In aortic rings, the vascular reactivity to ANG II and ANG-(1-7) was assessed. Expression of ANG-(1-7) in aortic wall was analyzed by immunohistochemistry. The results showed that both exercise and ET increased plasma ANG II levels despite attenuating systolic blood pressure. Ovariectomy increased constrictor responses to ANG II and decreased dilatory responses to ANG-(1-7), which were reversed by swimming independently of ET. Moreover, it was observed an apparent increase in ANG-(1-7) content in the aorta of the groups subjected to training and ET. Exercise training may play a cardioprotective role independently of ET and may be an alternative to ET in hypertensive postmenopausal women.