Sex differences in the modulation of vasomotor sympathetic outflow during static handgrip exercise in healthy young humans
Publication year
2011Source
American Journal of Physiology : Regulatory Integrative and Comparative Physiology, 301, 1, (2011), pp. R193-200ISSN
Publication type
Article / Letter to editor

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Organization
Geriatrics
Journal title
American Journal of Physiology : Regulatory Integrative and Comparative Physiology
Volume
vol. 301
Issue
iss. 1
Page start
p. R193
Page end
p. 200
Subject
NCEBP 11: Alzheimer Centre; NCEBP 14: Cardiovascular diseasesAbstract
Sex differences in sympathetic neural control during static exercise in humans are few and the findings are inconsistent. We hypothesized women would have an attenuated vasomotor sympathetic response to static exercise, which would be further reduced during the high sex hormone [midluteal (ML)] vs. the low hormone phase [early follicular (EF)]. We measured heart rate (HR), blood pressure (BP), and muscle sympathetic nerve activity (MSNA) in 11 women and 10 men during a cold pressor test (CPT) and static handgrip to fatigue with 2 min of postexercise circulatory arrest (PECA). HR increased during handgrip, reached its peak at fatigue, and was comparable between sexes. BP increased during handgrip and PECA where men had larger increases from baseline. Mean +/- SD MSNA burst frequency (BF) during handgrip and PECA was lower in women (EF, P < 0.05), as was DeltaMSNA-BF smaller (main effect, both P < 0.01). DeltaTotal activity was higher in men at fatigue (EF: 632 +/- 418 vs. ML: 598 +/- 342 vs. men: 1,025 +/- 416 a.u./min, P < 0.001 for EF and ML vs. men) and during PECA (EF: 354 +/- 321 vs. ML: 341 +/- 199 vs. men: 599 +/- 327 a.u./min, P < 0.05 for EF and ML vs. men). During CPT, HR and MSNA responses were similar between sexes and hormone phases, confirming that central integration and the sympathetic efferent pathway was comparable between the sexes and across hormone phases. Women demonstrated a blunted metaboreflex, unaffected by sex hormones, which may be due to differences in muscle mass or fiber type and, therefore, metabolic stimulation of group IV afferents.
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- Faculty of Medical Sciences [86198]
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