Journal article
Sympathetic nervous system activation reduces contraction-induced rapid vasodilation in the leg of humans independent of age
Journal of applied physiology (1985), Vol.123(1), pp.106-115
07/01/2017
DOI: 10.1152/japplphysiol.00005.2017
PMCID: PMC6157482
PMID: 28385914
Abstract
Contraction-induced rapid vasodilation is attenuated similarly in the upper and lower limbs of older adults. In the forearm, this attenuation is in part due to a greater sympathetic vasoconstriction. We examined whether the age-related reduction in contraction-induced vasodilation in the leg is also due to a sympathetic vasoconstrictive mechanism. Thirteen young (24 ± 1 yr) and twelve older adults (67 ± 1 yr) performed single-leg knee extension at 20 and 40% of work-rate maximum (WR
) during control and cold-pressor test (CPT) conditions. Femoral artery diameter and blood velocity were measured using Doppler ultrasound. Vascular conductance (VC; ml·min
·mmHg
) was calculated using blood flow (ml/min) and mean arterial pressure (mmHg). Peak (ΔVC from baseline) and total VC were blunted in older adults during control conditions across exercise intensities (
< 0.05). Peak and total VC were reduced during CPT in both age groups across exercise intensities (
< 0.05). The relative change (i.e., %reduction; CPT vs. control) in peak (-25 ± 5 vs. -22 ± 4% at 20% WR
; and -21 ± 6 vs. -27 ± 5% at 40% WR
;
= 0.42-0.55) and total VC (-28 ± 5 vs. -36 ± 6% at 20% WR
; and -22 ± 8 vs. -33 ± 5% at 40% WR
;
= 0.23-0.34) were similar between young and older adults. When matched for absolute workload (~10 W), age differences persisted in peak VC (
< 0.05) under both conditions, with similar relative changes in peak and total VC during CPT. Our data suggest that
) sympathetic stimulation reduces contraction-induced rapid vasodilation in the leg of young and older adults similarly; and
) enhanced sympathetic vasoconstriction does not fully explain age-related differences in contraction-induced vasodilation within the leg.
Aging is associated with attenuated contraction-induced rapid onset vasodilation (ROV). Within the forearm, this attenuation is partially due to enhanced sympathetic vasoconstriction. In the current study, we found that sympathetic vasoconstriction reduces contraction-induced ROV within the leg of both young and older adults, with the magnitude of change being similar between age groups. Our current results suggest that age-related attenuations in contraction-induced ROV within the leg are not fully explained by a sympathetic vasoconstrictor mechanism.
Details
- Title: Subtitle
- Sympathetic nervous system activation reduces contraction-induced rapid vasodilation in the leg of humans independent of age
- Creators
- William E Hughes - Department of Physical Therapy and Rehabilitation Science, Carver College of Medicine, University of Iowa, Iowa City, IowaNicholas T Kruse - Abboud Cardiovascular Research Center, Carver College of Medicine, University of Iowa, Iowa City, Iowa; andDarren P Casey - Fraternal Order of Eagles Diabetes Research, Carver College of Medicine, University of Iowa, Iowa City, Iowa
- Resource Type
- Journal article
- Publication Details
- Journal of applied physiology (1985), Vol.123(1), pp.106-115
- Publisher
- United States
- DOI
- 10.1152/japplphysiol.00005.2017
- PMID
- 28385914
- PMCID
- PMC6157482
- ISSN
- 8750-7587
- eISSN
- 1522-1601
- Grant note
- R00 HL105467 / NHLBI NIH HHS
- Language
- English
- Date published
- 07/01/2017
- Academic Unit
- Physical Therapy and Rehabilitation Science; Fraternal Order of Eagles Diabetes Research Center; Internal Medicine
- Record Identifier
- 9984047705702771
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