Cardiac baroreflex sensitivity was positively associated with the magnitude of systolic blood pressure decrease during a hypotensive challenge in young men and older women, but not in young women.
Cross-Sectional (n=101)
No
Does sex and menopausal status influence the association between cardiac baroreflex sensitivity and blood pressure transients during a vasoactive drug bolus?
Cardiac baroreflex sensitivity plays a more prominent role in responding to acute blood pressure changes in young men and older women compared to young women, suggesting an influence of female sex hormones on baroreflex responses.
Effect estimate: r = 0.60 (older women); r = 0.41 (young men)
p-value: p=<0.05
The magnitude of decrease in blood pressure (BP) during a vasoactive drug bolus may be associated with the calculated baroreflex sensitivity (BRS). The purpose of the present study was to evaluate whether sympathetic and/or cardiac BRS relates to the extent of change in BP and whether this was altered by sex hormones. Fifty-one young women (27 ± 1 years), 14 older women (58 ± 1 years), and 36 young men (27 ± 1 years) were studied. Heart rate, BP, and muscle sympathetic nerve activity (MSNA) were monitored. Sympathetic BRS was analyzed using the slope of the MSNA-diastolic blood pressure (DBP) relationship and cardiac BRS was analyzed using the R-R interval-systolic blood pressure (SBP) relationship. Young women and men had similar mean arterial pressures (MAP, 91 ± 1 vs. 90 ± 1 mmHg), cardiac BRS (19 ± 1 vs. 21 ± 2 ms/mmHg), and sympathetic BRS (-6 ± 1 vs. -7 ± 1 AU/beat/mmHg), respectively. Older women had higher MAP (104 ± 4 mmHg, p < 0.05) and lower cardiac BRS (7 ± 1 ms/mmHg, p < 0.05), but similar sympathetic BRS (-8 ± 1 AU/beat/mmHg). There was no association between BP transients with either cardiac or sympathetic BRS in young women. In the older women, the drop in SBP, DBP, and MAP were associated with cardiac BRS (r = 0.60, r = 0.59, and r = 0.70, respectively; p < 0.05), but not sympathetic BRS. The decrease in SBP was positively related to cardiac BRS in young men (r = 0.41; p < 0.05). However, there was no relationship between the decrease in BP and sympathetic BRS. This indicates that older women and young men with low cardiac BRS have larger transients in BP during nitroprusside. This suggests a more prominent role for cardiac (as opposed to sympathetic) BRS in responding to acute BP changes in young men and older women. The fact that these relationships do not exist in young women suggest that the female sex hormones influence baroreflex responses.
Barnes et al. (Sun,) conducted a cross-sectional in Healthy subjects (n=101). Sex and menopausal status vs. Young men and young women was evaluated on Correlation between cardiac baroreflex sensitivity (BRS) and the magnitude of decrease in systolic blood pressure (SBP) during nitroprusside infusion (r = 0.60 (older women); r = 0.41 (young men), p=<0.05). Cardiac baroreflex sensitivity was positively associated with the magnitude of systolic blood pressure decrease during a hypotensive challenge in young men and older women, but not in young women.