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Broader adaptive range of sympathetic burst size in response to blood pressure change in older women with greater arterial stiffness
Author(s) -
Okada Yoshiyuki,
Galbreath M. Melyn,
Jarvis Sara S.,
Shibata Shigeki,
Vongpatanasin Wanpen,
Levine Benjamin D.,
Fu Qi
Publication year - 2020
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jp279877
Subject(s) - medicine , baroreflex , blood pressure , cardiology , supine position , arterial stiffness , common carotid artery , heart rate , carotid arteries
Key points In this study, we focused on muscle sympathetic nerve activity (MSNA) burst size and occurrence separately as subcomponents of the sympathetic baroreflex in older adults, and we found that the distribution (variation) of burst size against burst occurrence was greater in women than men. Older women had greater carotid artery stiffness compared with older men, while blood pressure (BP) distribution (variation) was comparable between sexes. Sympathetic baroreflex sensitivity assessed with burst incidence was less sensitive as the carotid artery became stiffer in older men and women, while that assessed with burst area was more sensitive as the carotid artery became stiffer in older women but not in older men. These results help us understand the mechanisms underlying the compensation for the impaired response of MSNA burst occurrence in older women with greater carotid artery stiffness to regulate BP similar to that in older men.Abstract There are sex differences in arterial stiffness and neural control of blood pressure (BP) among older adults. We examined whether the sympathetic response to BP is greater in older women than men in burst size but not burst occurrence. Burst occurrence and size were assessed with burst interval and area of muscle sympathetic nerve activity, respectively, and the distributions of these indices were evaluated by range during supine rest in 61 healthy older subjects (30 men (69 ± 6 years) and 31 women (68 ± 6 years); means ± SD). Also, we analysed sympathetic baroreflex sensitivity (BRS) with burst occurrence and area simultaneously. Carotid β‐stiffness was measured with B‐mode ultrasonic image and carotid BP. The range of burst interval was smaller in older women than men ( P = 0.002), while there was no difference in the range of burst area. Carotid β‐stiffness was greater in older women than men (6.7 ± 2.7 vs . 5.1 ± 2.7, P = 0.027). Sympathetic BRS assessed with burst incidence was lower in older women than men (‐2.3 ± 1.4 vs . ‐3.3 ± 1.4 bursts·100 beats ‐1 mmHg ‐1 , P = 0.007), while this sex difference was observed when assessed with burst area after adjusting for carotid β‐stiffness (‐116.1 ± 135.0 vs . ‐185.9 ± 148.2 a.u. burst ‐1 mmHg ‐1 , P = 0.040), but not before. Sympathetic BRS assessed with burst area was negatively (more sensitive) correlated with carotid β‐stiffness in older women ( r = ‐0.53, P = 0.002) but not men. These data suggest that the response of burst size within each burst is augmented for the baroreflex BP control despite the impaired response of burst occurrence in older women with greater carotid stiffness.