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Attenuated noradrenergic sensitivity during local cooling in aged human skin
Caitlin S Thompson1, Lacy A Holowatz, W Larry Kenney
1The Pennsylvania State University, 119 Noll Laboratory, University Park, PA 16802, USA. cst116@psu.edu
The Journal of Physiology
|February 12, 2005
Summary
Older skin shows reduced ability to constrict blood vessels when cooled and exposed to noradrenaline (NA). This impaired cutaneous vasoconstriction (VC) may be linked to age-related changes in calcium or receptor function.
Area of Science:
- Physiology
- Gerontology
- Dermatology
Background:
- Reflex-mediated cutaneous vasoconstriction (VC) is known to be impaired in older adults.
- The mechanisms of VC during local cooling, distinct from reflex pathways, are less understood in aging.
- This study investigates age-related differences in local cooling-induced VC sensitization to noradrenaline (NA).
Purpose of the Study:
- To test if the sensitization of cutaneous vessels to noradrenaline (NA) during local skin cooling is blunted in older individuals compared to younger ones.
- To investigate the dose-dependent vasoconstrictive response to NA during local cooling in different age groups.
- To explore potential underlying mechanisms for age-related differences in cutaneous vascular responses.
Main Methods:
- Recruited 11 young (18-30 years) and 11 older (62-76 years) participants.
- Monitored skin blood flow using laser Doppler (LD) flowmetry at two forearm sites, with local skin temperature cooled to 24°C.
- Administered sequential intradermal microdialysis infusions of noradrenaline (NA) at one site and a control solution at the other, measuring cutaneous vascular conductance (CVC).
Main Results:
- Local cooling induced similar vasoconstriction (VC) in both young and older groups (-54% vs -56% DeltaCVC(base)).
- In young individuals, NA infusions during cooling caused a dose-dependent increase in VC, starting at lower NA concentrations.
- Older individuals showed significantly blunted VC response to NA, with significant constriction only occurring at the highest NA dose (10(-2) m).
Conclusions:
- Young skin exhibits enhanced vasoconstrictive capacity to noradrenaline (NA) when sensitized by local cooling.
- Older skin demonstrates a significantly blunted response to NA under cooling conditions, requiring higher doses for a similar effect.
- Age-associated decrements in calcium availability or alpha2C-adrenoceptor function may underlie the impaired vascular response in older skin.