Vasomotor symptoms of menopause, sympathetic activity, and blood pressure in postmenopausal females

Abstract

Although evidence suggests an association between vasomotor symptoms (VMS; hot flushes and night sweats) and elevated blood pressure (BP), it remains unknown whether females who experience VMS have elevated muscle sympathetic nerve activity (MSNA), a major modulator of BP. We hypothesized that postmenopausal females with VMS would have elevated BP and MSNA at rest and during stress compared with age-matched females without VMS. Participants were grouped based on whether they currently or previously experienced VMS (n = 43) or never experienced VMS (non-VMS; n = 26). Heart rate (HR: electrocardiography), BP (finger plethysmography), and MSNA (microneurography) were recorded during a 10-min rest, a 2-min cold pressor test (CPT), and a 5-min recovery. Although there were no group differences in resting mean arterial pressure (MAP) or MSNA burst frequency (P > 0.05), MSNA burst incidence (53 ± 13 vs. 44 ± 9 bursts/100 heartbeats, P < 0.01) was greater in the VMS group. Resting HR was lower in the VMS group (58 ± 10 vs. 62 ± 9 beats/min, P = 0.04), and the standard deviation of the RR-interval HR variability (52 ± 21 vs. 38 ± 16 ms, P < 0.01), total cardiovagal baroreflex (cBRS; 12 ± 6 vs. 9 ± 3 ms/mmHg, P = 0.02), and cBRS down (cBRSdown; 12 ± 6 vs. 9 ± 4 ms/mmHg, P = 0.01) calculated via the sequence method were greater than the non-VMS group. HR, MAP, and MSNA responsiveness to CPT were not different between groups (P > 0.05). Contrary to our initial hypothesis, postmenopausal females with current or prior VMS demonstrated similar BP and MSNA burst frequency, with greater cardiovagal modulation and baroreflex sensitivity compared with the non-VMS group. Future work on this paradoxical finding appears warranted.NEW & NOTEWORTHY Postmenopausal females, who are otherwise healthy and experience VMS of menopause, did not exhibit heightened MSNA and BP but demonstrated elevated HRV, total cBRS, cBRSdown, and a lower HR compared with postmenopausal females with no current or previous history of VMS. These findings suggest that healthy females with mild to moderate VMS do not exhibit autonomic dysregulation when compared with females who have never experienced VMS.

Keywords: aging; autonomic function; hot flushes.