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Nitric oxide and attenuated reflex cutaneous vasodilation in aged skin
Lacy A Holowatz1, Belinda L Houghton, Brett J Wong
1Department of Exercise and Movement Science, University of Oregon, Eugene, OR 97403-1240, USA.
American Journal of Physiology. Heart and Circulatory Physiology
|December 31, 2002
Summary
Nitric oxide (NO)-dependent pathways play a larger role in skin vasodilation in older adults. This suggests age-related declines in skin blood flow may involve reduced NO signaling or responsiveness.
Area of Science:
- Physiology
- Gerontology
- Cardiovascular Science
Background:
- Thermoregulatory cutaneous vasodilation is impaired in older individuals.
- The underlying mechanisms for this age-related decline are not fully understood.
Purpose of the Study:
- To investigate the contribution of nitric oxide (NO)-dependent mechanisms to attenuated reflex cutaneous vasodilation in older adults.
- To test the hypothesis that reduced NO signaling contributes to diminished skin blood flow regulation in the elderly.
Main Methods:
- Microdialysis was used to infuse N(G)-nitro-l-arginine methyl ester (to inhibit NO synthase) or Ringer solution in the forearm skin of young and older men.
- Core temperature was increased by 1.0°C using water-perfused suits.
- Cutaneous vascular conductance (CVC) was measured using laser-Doppler flowmetry and expressed as a percentage of maximal vasodilation.
Main Results:
- Nitric oxide synthase inhibition significantly reduced CVC in both young and older subjects.
- The relative contribution of NO-dependent vasodilation was greater in older subjects (60%) compared to young subjects (23%) during hyperthermia.
- Older adults showed a more pronounced reduction in CVC upon NOS inhibition.
Conclusions:
- Nitric oxide-mediated pathways are more critical for cutaneous active vasodilation in older adults during hyperthermia.
- Age-related attenuation of cutaneous vasodilation may stem from diminished NO production or reduced vascular responsiveness to vasodilatory signals.