Age-specific modification of local cutaneous vasodilation by capsaicin-sensitive primary afferents

Thayne A. Munce, W. Larry Kenney

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Abstract

Age-related changes in neurogenic vasodilation mediated by sensory nerves may alter local skin blood flow (SkBF) responses in older individuals. The purpose of this study was to determine the age-specific modification of cutaneous vasodilation by capsaicin-sensitive primary afferent (CSPA) nerves during local heating. Nine young (18-30 yr), eight middle-aged (40-55 yr), and eight older (65-80 yr) healthy men participated in the experiments. Two local-heating protocols (rapid and slow) were performed before and after 1 wk of capsaicin pretreatment (CP), used to desensitize CSPAs. All temperatures were below those that elicit pain. SkBF was measured with a laser-Doppler imager and indexed to percentage of maximal cutaneous vascular conductance (%CVCmax). CP caused a significant reduction in %CVCmax in the middle-aged and older groups during slow heating (P < 0.05), without affecting %CVCmax in the young group. During rapid heating, CP significantly reduced (53.9 ± 4.4 vs. 74.4 ± 7.4% CVC max, P < 0.05), but did not abolish, the initial sensory nerve-mediated rise in SkBF in the young group. No significant effects of CP on SkBF were observed during rapid heating in the middle-aged or older groups. These results indicate that, with advanced age, CSPA activity is more important to the maximal SkBF response during prolonged local heating, whereas it has a reduced role in the initial SkBF peak elicited by rapid local heating. In summary, CSPA activity contributes modestly to the overall SkBF response to local heating in an age-specific manner.

Original languageEnglish (US)
Pages (from-to)1016-1024
Number of pages9
JournalJournal of Applied Physiology
Volume95
Issue number3
DOIs
StatePublished - Sep 1 2003

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Keywords

  • Aging
  • Laser-Doppler imaging
  • Skin blood flow

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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