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Nitric oxide and attenuated reflex cutaneous vasodilation in aged skin.
Holowatz, Lacy A; Houghton, Belinda L; Wong, Brett J; Wilkins, Brad W; Harding, Aaron W; Kenney, W Larry; Minson, Christopher T.
Afiliação
  • Holowatz LA; Department of Exercise and Movement Science, University of Oregon, Eugene, OR 97403-1240, USA.
Am J Physiol Heart Circ Physiol ; 284(5): H1662-7, 2003 May.
Article em En | MEDLINE | ID: mdl-12505876
Thermoregulatory cutaneous vasodilation is diminished in the elderly. The goal of this study was to test the hypothesis that a reduction in nitric oxide (NO)-dependent mechanisms contributes to the attenuated reflex cutaneous vasodilation in older subjects. Seven young (23 +/- 2 yr) and seven older (71 +/- 6 yr) men were instrumented with two microdialysis fibers in the forearm skin. One site served as control (Ringer infusion), and the second site was perfused with 10 mM N(G)-nitro-l-arginine methyl ester to inhibit NO synthase (NOS) throughout the protocol. Water-perfused suits were used to raise core temperature 1.0 degrees C. Red blood cell (RBC) flux was measured with laser-Doppler flowmetry over each microdialysis fiber. Cutaneous vascular conductance (CVC) was calculated as RBC flux per mean arterial pressure, with values expressed as a percentage of maximal vasodilation (infusion of 28 mM sodium nitroprusside). NOS inhibition reduced CVC from 75 +/- 6% maximal CVC (CVC(max)) to 53 +/- 3% CVC(max) in the young subjects and from 64 +/- 5% CVC(max) to 29 +/- 2% CVC(max) in the older subjects with a 1.0 degrees C rise in core temperature. Thus the relative NO-dependent portion of cutaneous active vasodilation (AVD) accounted for approximately 23% of vasodilation in the young subjects and 60% of the vasodilation in the older subjects at this level of hyperthermia (P < 0.001). In summary, NO-mediated pathways contributed more to the total vasodilatory response of the older subjects at high core temperatures. This suggests that attenuated cutaneous vasodilation with age may be due to a reduction in, or decreased vascular responsiveness to, the unknown neurotransmitter(s) mediating AVD.
Assuntos
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Base de dados: MEDLINE Assunto principal: Reflexo / Pele / Vasodilatação / Envelhecimento / Óxido Nítrico Limite: Adult / Aged / Humans / Male Idioma: En Ano de publicação: 2003 Tipo de documento: Article
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Base de dados: MEDLINE Assunto principal: Reflexo / Pele / Vasodilatação / Envelhecimento / Óxido Nítrico Limite: Adult / Aged / Humans / Male Idioma: En Ano de publicação: 2003 Tipo de documento: Article