Aging induced additional impairment in cardiovascular control in ovariectomized rats

Abstract

The objective was to investigate the effects of aging on cardiovascular parameters in females rats submitted to ovarian hormones deprivation. Female Wistar rats were divided into 4 groups (n=8 each group): young adult (2–3 mo, YA), aged (18 mo, AG), young adult ovariectomized (YA-OVX) and aged ovariectomized (AG-OVX). Arterial pressure (AP) and heart rate (HR) signals were directly recorded in conscious rats. The baroreflex sensitivity (BRS) was evaluated by tachycardic (TR) and bradycardic (BR) responses. The ovariectomy, associated or not with aging, induced increase in AP values (YA-OVX: 124±1.35 and AG-OVX: 136±7.06 vs. YA: 112±2.56 mmHg). There was an additional AP increase in AG-OVX in relation to YA-OVX and AG rats (120±2.6 mmHg). The HR was enhanced in AG, YA-OVX, AG-OVX when compared with YA group. The BR and TR were impaired in AG (0.83±0.06 and 1.50±0.28 bpm/mmHg) as compared to YA group (1.27±0.08 and –3.70±0.30 bpm/mmHg). Ovariectomy (YA-OVX: 1.09±0.08 and 2.11±0.21 and AG-OVX: 0.54±0.05 and –0.88±0.33 bpm/mmHg) decreased both BR and TR in relation to YA and AG groups. Furthermore, BRS was additionally reduced in AG-OVX as compared to YA-OVX rats. These results demonstrated that the ovarian hormone deprivation impact on arterial pressure and BRS is aged dependent.