Journal article
Impaired increases in skin sympathetic nerve activity contribute to age-related decrements in reflex cutaneous vasoconstriction
The Journal of physiology, Vol.593(9), pp.2199-2211
05/01/2015
DOI: 10.1113/JP270062
PMCID: PMC4422572
PMID: 25752518
Abstract
Reflex cutaneous vasoconstriction is impaired in older adults; however, the relative roles of altered skin sympathetic nerve activity (SSNA) and end-organ peripheral vascular responsiveness are unclear. We hypothesized that in older adults whole-body cooling would elicit a blunted SSNA response and cutaneous adrenergic responsiveness would be reduced. Twelve young adults (Y; 24 +/- 1 years) and 12 older adults (O; 57 +/- 2 years) participated in two protocols. In Protocol 1, SSNA (peroneal microneurography) and red cell flux in the affected dermatome (laser Doppler flowmetry; dorsum of foot) were measured during whole-body cooling (mean skin temperature (T-sk) 30.5 degrees C; water-perfused suit). Mental stress was performed at mean T-sk 34.0 degrees C (thermoneutral) and at 30.5 degrees C. In Protocol 2, an intradermal microdialysis fibre was placed in the skin of the lateral calf for graded infusions of noradrenaline (norepinephrine) (NA; 10(-12) to 10(-2) M). Cutaneous vascular conductance (CVC = flux/mean arterial pressure) was expressed as a change from baseline (Delta CVCbase). Vasoconstriction was attenuated in O. SSNA increased significantly during cooling in Y(+184 +/- 37%; P < 0.05) but not O(+51 +/- 12%; P > 0.05). Mental stress at T-sk 30.5 degrees C further increased SSNA in both groups. There was no age-related difference in adrenergic responsiveness to exogenous NA (logEC(50): -6.41 +/- 0.24 in Y, -6.37 +/- 0.25 in O; P > 0.05). While the SSNA response to whole-body cooling is impaired with ageing, SSNA can be further increased by a non-thermoregulatory stimulus. Cutaneous adrenergic sensitivity is not reduced in O. These findings suggest that alterations in afferent signalling or central processing likely contribute to blunted SSNA responses to cooling and subsequent impairments in reflex cutaneous vasoconstriction in ageing.
Details
- Title: Subtitle
- Impaired increases in skin sympathetic nerve activity contribute to age-related decrements in reflex cutaneous vasoconstriction
- Creators
- Jody L. Greaney - Pennsylvania State UniversityAnna E. Stanhewicz - Pennsylvania State UniversityW. Larry Kenney - Pennsylvania State UniversityLacy M. Alexander - Pennsylvania State University
- Resource Type
- Journal article
- Publication Details
- The Journal of physiology, Vol.593(9), pp.2199-2211
- Publisher
- Wiley
- DOI
- 10.1113/JP270062
- PMID
- 25752518
- PMCID
- PMC4422572
- ISSN
- 0022-3751
- eISSN
- 1469-7793
- Number of pages
- 13
- Grant note
- R29AG007004 / NATIONAL INSTITUTE ON AGING; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA; NIH National Institute on Aging (NIA) F32HL120471 / NATIONAL HEART, LUNG, AND BLOOD INSTITUTE; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA; NIH National Heart Lung & Blood Institute (NHLBI)
- Language
- English
- Date published
- 05/01/2015
- Academic Unit
- Fraternal Order of Eagles Diabetes Research Center; Health and Human Physiology; Internal Medicine
- Record Identifier
- 9984259641302771
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