Evidence for reduced sympatholysis in leg resistance vasculature of healthy older women

Beth A. Parker, Sandra L. Smithmyer, Sara S. Jarvis, Samuel J. Ridout, James Anthony Pawelczyk, David Nathan Proctor

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

Inhibition of a sympathetic stimulus (i.e., sympatholysis) during forearm exercise is reduced with age in women. This age-related alteration has not been characterized in the lower extremity vasculature of women, and the potential for blunting of the conduit artery dilatory response to a sudden increase in shear stress [flow-mediated dilation (FMD)] has not been examined in older adults of either sex. In the present study, we assessed popliteal artery diameter and velocity (Doppler ultrasound) in 16 young (23 ± 1 yr) and 14 older (69 ± 1 yr) women after 5 min of distal calf occlusion (FMD), 3 min of hand immersion in ice water [cold pressor test (CPT)], and 5 min of distal calf occlusion combined with hand immersion in ice water (FMD+CPT). Peak popliteal conductance after 5-min ischemia was not significantly different in young vs. older women. During the combined stimulus (FMD+CPT), the magnitude of vasoconstriction in the calf (reduction in peak popliteal artery conductance) was similar (5-8%), despite reduced resting adrenergic sensitivity to CPT [young (Y): -27.3 ± 3.8%; older (O): -15.8 ± 2.2%; P < 0.05] and blunted muscle sympathetic nerve activity responses to CPT (Y: 12.7 ± 3.6 bursts/min; O: 7.8 ± 2.5 bursts/min; P < 0.05) in older women. Popliteal FMD, normalized to the shear stimulus, was attenuated by 60-70% in older women. Peak popliteal diameter, measured during the combined stimulus (FMD+CPT), was blunted in young but not in older women (Y FMD: 5.5 ± 0.1 mm; Y FMD+CPT: 5.4 ± 0.1 mm; P = 0.03; O FMD: 5.8 ± 0.2 mm; O FMD+CPT: 5.8 ± 0.2 mm). These results confirm previous findings of diminished reactivity in the conduit arteries of older humans and provide the first evidence of reduced sympatholysis in the leg resistance vasculature of older women.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume292
Issue number2
DOIs
StatePublished - Feb 1 2007

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Dilatation
Leg
Popliteal Artery
Ice
Immersion
Hand
Arteries
Doppler Ultrasonography
Water
Vasoconstriction
Forearm
Adrenergic Agents
Lower Extremity
Ischemia
Exercise
Muscles

All Science Journal Classification (ASJC) codes

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

Cite this

@article{ee3cdfd7770047499f6a8147e37392e0,
title = "Evidence for reduced sympatholysis in leg resistance vasculature of healthy older women",
abstract = "Inhibition of a sympathetic stimulus (i.e., sympatholysis) during forearm exercise is reduced with age in women. This age-related alteration has not been characterized in the lower extremity vasculature of women, and the potential for blunting of the conduit artery dilatory response to a sudden increase in shear stress [flow-mediated dilation (FMD)] has not been examined in older adults of either sex. In the present study, we assessed popliteal artery diameter and velocity (Doppler ultrasound) in 16 young (23 ± 1 yr) and 14 older (69 ± 1 yr) women after 5 min of distal calf occlusion (FMD), 3 min of hand immersion in ice water [cold pressor test (CPT)], and 5 min of distal calf occlusion combined with hand immersion in ice water (FMD+CPT). Peak popliteal conductance after 5-min ischemia was not significantly different in young vs. older women. During the combined stimulus (FMD+CPT), the magnitude of vasoconstriction in the calf (reduction in peak popliteal artery conductance) was similar (5-8{\%}), despite reduced resting adrenergic sensitivity to CPT [young (Y): -27.3 ± 3.8{\%}; older (O): -15.8 ± 2.2{\%}; P < 0.05] and blunted muscle sympathetic nerve activity responses to CPT (Y: 12.7 ± 3.6 bursts/min; O: 7.8 ± 2.5 bursts/min; P < 0.05) in older women. Popliteal FMD, normalized to the shear stimulus, was attenuated by 60-70{\%} in older women. Peak popliteal diameter, measured during the combined stimulus (FMD+CPT), was blunted in young but not in older women (Y FMD: 5.5 ± 0.1 mm; Y FMD+CPT: 5.4 ± 0.1 mm; P = 0.03; O FMD: 5.8 ± 0.2 mm; O FMD+CPT: 5.8 ± 0.2 mm). These results confirm previous findings of diminished reactivity in the conduit arteries of older humans and provide the first evidence of reduced sympatholysis in the leg resistance vasculature of older women.",
author = "Parker, {Beth A.} and Smithmyer, {Sandra L.} and Jarvis, {Sara S.} and Ridout, {Samuel J.} and Pawelczyk, {James Anthony} and Proctor, {David Nathan}",
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Evidence for reduced sympatholysis in leg resistance vasculature of healthy older women. / Parker, Beth A.; Smithmyer, Sandra L.; Jarvis, Sara S.; Ridout, Samuel J.; Pawelczyk, James Anthony; Proctor, David Nathan.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 292, No. 2, 01.02.2007.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Evidence for reduced sympatholysis in leg resistance vasculature of healthy older women

AU - Parker, Beth A.

AU - Smithmyer, Sandra L.

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AU - Pawelczyk, James Anthony

AU - Proctor, David Nathan

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N2 - Inhibition of a sympathetic stimulus (i.e., sympatholysis) during forearm exercise is reduced with age in women. This age-related alteration has not been characterized in the lower extremity vasculature of women, and the potential for blunting of the conduit artery dilatory response to a sudden increase in shear stress [flow-mediated dilation (FMD)] has not been examined in older adults of either sex. In the present study, we assessed popliteal artery diameter and velocity (Doppler ultrasound) in 16 young (23 ± 1 yr) and 14 older (69 ± 1 yr) women after 5 min of distal calf occlusion (FMD), 3 min of hand immersion in ice water [cold pressor test (CPT)], and 5 min of distal calf occlusion combined with hand immersion in ice water (FMD+CPT). Peak popliteal conductance after 5-min ischemia was not significantly different in young vs. older women. During the combined stimulus (FMD+CPT), the magnitude of vasoconstriction in the calf (reduction in peak popliteal artery conductance) was similar (5-8%), despite reduced resting adrenergic sensitivity to CPT [young (Y): -27.3 ± 3.8%; older (O): -15.8 ± 2.2%; P < 0.05] and blunted muscle sympathetic nerve activity responses to CPT (Y: 12.7 ± 3.6 bursts/min; O: 7.8 ± 2.5 bursts/min; P < 0.05) in older women. Popliteal FMD, normalized to the shear stimulus, was attenuated by 60-70% in older women. Peak popliteal diameter, measured during the combined stimulus (FMD+CPT), was blunted in young but not in older women (Y FMD: 5.5 ± 0.1 mm; Y FMD+CPT: 5.4 ± 0.1 mm; P = 0.03; O FMD: 5.8 ± 0.2 mm; O FMD+CPT: 5.8 ± 0.2 mm). These results confirm previous findings of diminished reactivity in the conduit arteries of older humans and provide the first evidence of reduced sympatholysis in the leg resistance vasculature of older women.

AB - Inhibition of a sympathetic stimulus (i.e., sympatholysis) during forearm exercise is reduced with age in women. This age-related alteration has not been characterized in the lower extremity vasculature of women, and the potential for blunting of the conduit artery dilatory response to a sudden increase in shear stress [flow-mediated dilation (FMD)] has not been examined in older adults of either sex. In the present study, we assessed popliteal artery diameter and velocity (Doppler ultrasound) in 16 young (23 ± 1 yr) and 14 older (69 ± 1 yr) women after 5 min of distal calf occlusion (FMD), 3 min of hand immersion in ice water [cold pressor test (CPT)], and 5 min of distal calf occlusion combined with hand immersion in ice water (FMD+CPT). Peak popliteal conductance after 5-min ischemia was not significantly different in young vs. older women. During the combined stimulus (FMD+CPT), the magnitude of vasoconstriction in the calf (reduction in peak popliteal artery conductance) was similar (5-8%), despite reduced resting adrenergic sensitivity to CPT [young (Y): -27.3 ± 3.8%; older (O): -15.8 ± 2.2%; P < 0.05] and blunted muscle sympathetic nerve activity responses to CPT (Y: 12.7 ± 3.6 bursts/min; O: 7.8 ± 2.5 bursts/min; P < 0.05) in older women. Popliteal FMD, normalized to the shear stimulus, was attenuated by 60-70% in older women. Peak popliteal diameter, measured during the combined stimulus (FMD+CPT), was blunted in young but not in older women (Y FMD: 5.5 ± 0.1 mm; Y FMD+CPT: 5.4 ± 0.1 mm; P = 0.03; O FMD: 5.8 ± 0.2 mm; O FMD+CPT: 5.8 ± 0.2 mm). These results confirm previous findings of diminished reactivity in the conduit arteries of older humans and provide the first evidence of reduced sympatholysis in the leg resistance vasculature of older women.

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