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This Article Full Text Full Text (PDF) All Versions of this Article: 577/3/925    most recent jphysiol.2006.116905v2 jphysiol.2006.116905v1 Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Keller, D. M. Articles by Crandall, C. G. Search for Related Content PubMed PubMed Citation Articles by Keller, D. M. Articles by Crandall, C. G. Related Collections Cardiovascular

¹ Institute for Exercise and Environmental Medicine, Presbyterian Hospital of Dallas, Dallas, TX 75231, USA
² Department of Internal Medicine, University of Texas South-western Medical Center, Dallas, TX 75390, USA
³ University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107, USA

Prior studies investigating carotid baroreflex control of the cutaneous vasculature have yielded mixed findings. However, previously used methodological and analytical techniques may limit the ability to detect carotid baroreflex-mediated changes in cutaneous vascular conductance (CVC). The aim of this study was to test the hypothesis that dynamic carotid baroreceptor stimulation (i.e. 5 s trials) using neck pressure (NP, simulated carotid hypotension) and neck suction (NS, simulated carotid hypertension) will decrease and increase CVC, respectively, during normothermic and whole-body heating conditions in resting humans. Data were obtained from nine subjects (age, 31 ± 2 year). The ratio of forearm skin blood flux (laser-Doppler flowmetry) and arterial blood pressure (Finapres) was used as an index of CVC. Multiple 5 s trials of NP (+40_Torr) and NS (–60_Torr), as well as breath-hold/airflow control trials, were applied during end-expiratory breath-holds while subjects were normotheric and heat stressed (change in core temperature 0.75°C). CVC responses to each NP and NS trial were averaged into 1 s intervals during the following periods: 3 s prestimulus, 5 s during stimulus, and 5 s poststimulus. Peak CVC responses (3 s average) to NP and NS were compared to prestimulus values using paired t test. During normothermia, NP decreased CVC by 0.032 ± 0.007 arbitrary units (a.u.) mmHg^–1; (P < 0.05); however, breath-hold/airflow control trials resulted in similar decreases in CVC. NS did not change CVC ( = 0.002 ± 0.005 a.u. mmHg^–1; P = 0.63). During whole-body heating, NP decreased CVC (by 0.16 ± 0.04 a.u. mmHg^–1; (P < 0.05), whereas NS increased CVC by 0.07 ± 0.03 a.u. mmHg^–1; (P < 0.05). Furthermore, these changes were greater than, or directionally different from, the breath-hold/airflow control trials. These findings indicate that carotid baroreceptor stimulation elicits dynamic changes in CVC and that these changes are more apparent during whole-body heating.

(Received 11 July 2006; accepted after revision 27 September 2006; first published online 5 October 2006)
Corresponding author C. G. Crandall: Institute for Exercise and Environmental Medicine, 7232 Greenville Ave., Dallas, TX 75231, USA. Email: craigcrandall{at}texashealth.org