Relationship Between Sympathetic Baroreflex Sensitivity and Arterial Stiffness in Elderly Men and Women

Abstract

Previous human studies have shown that large-artery stiffness contributes to an age-related decrease in cardiovagal baroreflex sensitivity. Whether this is also true with sympathetic baroreflex sensitivity is unknown. We tested the hypothesis that sympathetic baroreflex sensitivity is associated with the stiffness of baroreceptor segments (the carotid artery and the aorta) in elderly individuals, and that sex affects this relationship. Sympathetic baroreflex sensitivity was assessed from the spontaneous changes in beat-by-beat diastolic pressure and corresponding muscle sympathetic nerve activity (microneurography) during supine rest in 30 men [69±1 (mean±SEM) years] and 31 women (68±1 years). Carotid artery stiffness (B-mode ultrasonography) and aortic stiffness (magnetic resonance imaging) were also determined. We found that elderly women had lower sympathetic baroreflex sensitivity than elderly men (–2.33±0.25 vs. –3.32±0.25 bursts·100 beats–1·mmHg–1; P=0.007). β-stiffness indices of the carotid artery and the aorta were greater in elderly women than in men (6.68±0.48 vs. 5.10±0.50 and 4.03±0.47 vs. 2.68±0.42; both P<0.050). Sympathetic baroreflex sensitivity was inversely correlated with carotid artery stiffness in both men and women (r=0.49 and 0.50, both P<0.05), while this relation was shifted in parallel upward (towards a reduced sensitivity) in women with no changes in the slope (0.26 vs. 0.24 a.u.). Sympathetic baroreflex sensitivity and aortic stiffness showed similar trends. Thus, barosensory artery stiffness seems to be one independent determinant of sympathetic baroreflex sensitivity in elderly men and women. The lower sympathetic baroreflex sensitivity in elderly women may predispose them to an increased prevalence of hypertension.

Arterial Baroreflex Modulation of Sympathetic Activity and Arterial Wall Properties

“…The results clearly demonstrate a significant inverse correlation between the degree of carotid stiffness (␤-stiffness) and sympathetic BRS, whereas the data in relation to aortic stiffness are less clear (see below). 8 The main conclusion of the study that vascular BRS relates to arterial wall elasticity represents new information and nicely complements the findings reported previously on the relation between arterial stiffness and cardiac BRS. 6,7 The study by Okada et al, 8 however, offers intriguing information also with regard to gender differences in the relation between arterial stiffness and sympathetic BRS.…”

“…8 The main conclusion of the study that vascular BRS relates to arterial wall elasticity represents new information and nicely complements the findings reported previously on the relation between arterial stiffness and cardiac BRS. 6,7 The study by Okada et al, 8 however, offers intriguing information also with regard to gender differences in the relation between arterial stiffness and sympathetic BRS. Sympathetic BRS was overall lower in elderly women than in men, and, whereas the relationship between sympathetic BRS and arterial stiffness had the same slope in both genders, it was shifted upward in women (ie, at the same level of arterial stiffness, the baroreflex response was always smaller in women).…”

“…The article by Okada et al, 8 published in the current issue of Hypertension, was aimed at offering novel information in this regard. In 61 elderly subjects (30 men and 31 women), local arterial stiffness was assessed at carotid artery (ultrasonography) and aortic arch (magnetic resonance) level.…”

“…10 -12 This finding, however, given the limited specificity of the Valsalva maneuver in assessing arterial baroreflex sensitivity, 2 should also be confirmed using a more appropriate methodology. 13 Okada et al 8 suggest that gender differences in BRS may contribute to determination of BP levels and, thus, be relevant in the pathogenesis of hypertension. 8 However, impaired baroreflex function does not majorly affect differences in average BP but plays a crucial role in determining increased BP variability.…”

Treatment of Hypertension in the Oldest Old

“…Reduced cardiovagal baroreflex sensitivity may not only be related to the specific neural pathways but also to the number of functional β-adrenoceptors, which are diminished in older hypertensives. Recently, Okada et al 11 described that in older people (mean age, 69 years) the sympathetic component of the reflex is also impaired. The latter was derived from muscle sympathetic nerve activity recordings.…”