LASER-DOPPLER FLUX CHARACTERISTICS AT THE SKIN OF THE DORSUM OF THE FOOT IN YOUNG AND IN ELDERLY HEALTHY-HUMAN SUBJECTS

In aged human subjects the cutaneous circulation has shown reduced vas oreactive capacity when stimulated by heat or ischemia, and autonomic dysfunction developing in the elderly was suggested. Should this auton omic dysfunction affect the arteriolar vasomotional activity, it might be demonstrated by laser Doppler fluxmetry (LDF) at rest. LDF flow mo tion characteristics at the dorsal foot skin were investigated under r esting conditions in two subject groups differing in age. The younger group (n = 27, aged 25-29 years) showed a resting flux of 3.0 +/- 1.0 Arbitrary Units (AU) and a flux amplitude of 0.34 +/- 0.13 AU. In the elderly group (n = 22, aged 60-92 years) both these values were signif icantly (P < 0.05) lower (2.4 +/- 0.5 and 0.18 +/- 0.05 AU, respective ly). The flux frequency, on the contrary, was similar in both age grou ps: 4.9 cycles min(-1). We conclude that the mean resting flux and the mean flow motion amplitude under resting conditions at the skin of th e dorsum of the foot are significantly reduced in an old-age group. Th e latter finding might be an aging phenomenon affecting the microvascu lar tone and reactivity, and might be one of the elements responsible for the attenuated cutaneous vasoreactivity described in elderly human s in response to heat and ischemic stress. (C) 1997 Academic Press.