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Oxford University Press, American Journal of Hypertension, 6(32), p. 564-569, 2019

DOI: 10.1093/ajh/hpz035

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Age-Associated Differences in Central Artery Responsiveness to Sympathoexcitatory Stimuli

Journal article published in 2019 by Joshua M. Bock ORCID, William E. Hughes, Darren P. Casey ORCID
This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Abstract

Abstract BACKGROUND Age-associated arterial stiffening may be the result of greater tonic sympathetic nerve activity. However, age-associated changes in central artery responsiveness to sympathoexcitatory stimuli are understudied. Therefore, we examined changes in central artery stiffness and wave reflection in response to sympathoexcitatory stimuli in young and older adults. METHODS Fourteen young (25 ± 4 years) and 15 older (68 ± 4 years) subjects completed 3 minutes of the cold pressor test (CPT) and lower-body negative pressure (LBNP) separated by 15 minutes. Carotid–femoral pulse wave velocity (cfPWV), central augmentation pressure (cAP), and augmentation index (AIx) were measured in duplicate during rest and the final minute of each perturbation. RESULTS Young subjects had lower baseline cfPWV, cAP, and AIx than older subjects (P < 0.05 for all). During the CPT mean arterial pressure (MAP), cfPWV, cAP, and AIx increased in both groups (P < 0.05 for all); however, changes (Δ) in MAP (18 ± 7 vs. 9 ± 5 mm Hg), cfPWV (1.3 ± 0.7 vs. 0.6 ± 0.9 m/s), cAP (4 ± 2 vs. 6 ± 3 mm Hg), and AIx (18 ± 9% vs. 7 ± 4%) were greater in young vs. older subjects, respectively (P < 0.05 for all). With MAP as a covariate, cfPWV, cAP, and AIx responses to the CPT were no longer significantly different between groups. During LBNP, changes in MAP (–1 ± 3 vs. –3 ± 5 mm Hg), cfPWV (0.5 ± 0.3 vs. 0.5 ± 0.7 m/s), cAP (–2 ± 2 vs. –2 ± 3 mm Hg), and AIx (–7 ± 7% vs. –3 ± 6%) were similar between young and older groups, respectively (P > 0.05 for all). CONCLUSIONS Collectively, our data suggest the sympathetic nervous system may directly modulate central hemodynamics and that age-associated differences in central artery responsiveness to sympathoexcitatory stimuli are largely attributable to differential blood pressure responses.