Baroreceptor modulation of active cutaneous vasodilation during dynamic exercise
in humans.
Mack, Gary W., Doug Cordero, and Jochen Peters.
John B. Pierce Laboratory and Department of Epidemiology and Public Health, Yale
University School of Medicine, New Haven, Connecticut 06515
APStracts 8:0027A, 2001.
The hypothesis that baroreceptor unloading during dynamic limits cutaneous vasodilation
by withdrawal of active vasodilator activity was tested in seven human subjects.
Increases in forearm skin blood flow (laser-Doppler velocimetry) at skin sites with
(control) and without a-adrenergic vasoconstrictor activity (vasodilator only) and in
arterial blood pressure (noninvasive) were measured and used to calculate cutaneous
vascular conductance (CVC). Subjects performed two similar dynamic exercise (119 ± 8
W) protocols with and without baroreceptor unloading induced by application of
«minus»40 mmHg lower body negative pressure (LBNP). The LBNP condition was
reversed (i.e., either removed or applied) after 15 min while exercise continued for an
additional 15 min. During exercise without LBNP, the increase in body core temperature
(esophageal temperature) required to elicit active cutaneous vasodilation averaged 0.25 ±
0.08 and 0.31 ± 0.10°C (SE) at control and vasodilator-only skin sites, respectively, and
increased to 0.44 ± 0.10 and 0.50 ± 0.10°C (P < 0.05 compared with without LBNP)
during exercise with LBNP. During exercise baroreceptor unloading delayed the onset of
cutaneous vasodilation and limited peak CVC at vasodilator-only skin sites. These data
support the hypothesis that during exercise baroreceptor unloading modulates active
cutaneous vasodilation.
Received 13 December 1999; accepted in final form 22 November 2000
APS Manuscript Number A1052-9.
Article publication pending J Appl Physiol
ISSN 1080-4757 Copyright 2001 The American Physiological Society.
Published in APStracts on 29 January 2001