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Heat acclimation increases skin vasodilation and sweating but not cardiac baroreflex responses in heat-stressed humans.
J Appl Physiol (1985). 2003 Oct; 95(4):1567-74.JA

Abstract

In the present study, to test the hypothesis that exercise-heat acclimation increases orthostatic tolerance via the improvement of cardiac baroreflex control in heated humans, we examined cardiac baroreflex and thermoregulatory responses, including cutaneous vasomotor and sudomotor responses, during whole body heating before and after a 6-day exercise-heat acclimation program [4 bouts of 20-min exercise at 50% peak rate of oxygen uptake separated by 10-min rest in the heat (36 degrees C; 50% relative humidity)]. Ten healthy young volunteers participated in the study. On the test days before and after the heat acclimation program, subjects underwent whole body heat stress produced by a hot water-perfused suit during supine rest for 45 min and 75 degrees head-up tilt (HUT) for 6 min. The sensitivity of the arterial baroreflex control of heart rate (HR) was calculated from the spontaneous changes in beat-to-beat arterial pressure and HR. The HUT induced a presyncopal sign in seven subjects in the preacclimation test and in six subjects in the postacclimation test, and the tilting time did not differ significantly between the pre- (241 +/- 33 s) and postacclimation (283 +/- 24 s) tests. Heat acclimation did not change the slope in the HR-esophageal temperature (Tes) relation and the cardiac baroreflex sensitivity during heating. Heat acclimation decreased (P < 0.05) the Tes thresholds for cutaneous vasodilation in the forearm and dorsal hand and for sweating in the forearm and chest. These findings suggest that short-term heat acclimation does not alter the spontaneous baroreflex control of HR during heat stress, although it induces adaptive change of the heat dissipation response in nonglabrous skin.

Authors+Show Affiliations

Dept. of Clinical Pathophysiology, School of Health Sciences, Univ. of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, 807-8555 Kitakyushu, Japan. yamazaki@health.uoeh-u.ac.jpNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

12794028

Citation

Yamazaki, Fumio, and Kunshige Hamasaki. "Heat Acclimation Increases Skin Vasodilation and Sweating but Not Cardiac Baroreflex Responses in Heat-stressed Humans." Journal of Applied Physiology (Bethesda, Md. : 1985), vol. 95, no. 4, 2003, pp. 1567-74.
Yamazaki F, Hamasaki K. Heat acclimation increases skin vasodilation and sweating but not cardiac baroreflex responses in heat-stressed humans. J Appl Physiol (1985). 2003;95(4):1567-74.
Yamazaki, F., & Hamasaki, K. (2003). Heat acclimation increases skin vasodilation and sweating but not cardiac baroreflex responses in heat-stressed humans. Journal of Applied Physiology (Bethesda, Md. : 1985), 95(4), 1567-74.
Yamazaki F, Hamasaki K. Heat Acclimation Increases Skin Vasodilation and Sweating but Not Cardiac Baroreflex Responses in Heat-stressed Humans. J Appl Physiol (1985). 2003;95(4):1567-74. PubMed PMID: 12794028.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Heat acclimation increases skin vasodilation and sweating but not cardiac baroreflex responses in heat-stressed humans. AU - Yamazaki,Fumio, AU - Hamasaki,Kunshige, Y1 - 2003/06/06/ PY - 2003/6/10/pubmed PY - 2004/4/29/medline PY - 2003/6/10/entrez SP - 1567 EP - 74 JF - Journal of applied physiology (Bethesda, Md. : 1985) JO - J Appl Physiol (1985) VL - 95 IS - 4 N2 - In the present study, to test the hypothesis that exercise-heat acclimation increases orthostatic tolerance via the improvement of cardiac baroreflex control in heated humans, we examined cardiac baroreflex and thermoregulatory responses, including cutaneous vasomotor and sudomotor responses, during whole body heating before and after a 6-day exercise-heat acclimation program [4 bouts of 20-min exercise at 50% peak rate of oxygen uptake separated by 10-min rest in the heat (36 degrees C; 50% relative humidity)]. Ten healthy young volunteers participated in the study. On the test days before and after the heat acclimation program, subjects underwent whole body heat stress produced by a hot water-perfused suit during supine rest for 45 min and 75 degrees head-up tilt (HUT) for 6 min. The sensitivity of the arterial baroreflex control of heart rate (HR) was calculated from the spontaneous changes in beat-to-beat arterial pressure and HR. The HUT induced a presyncopal sign in seven subjects in the preacclimation test and in six subjects in the postacclimation test, and the tilting time did not differ significantly between the pre- (241 +/- 33 s) and postacclimation (283 +/- 24 s) tests. Heat acclimation did not change the slope in the HR-esophageal temperature (Tes) relation and the cardiac baroreflex sensitivity during heating. Heat acclimation decreased (P < 0.05) the Tes thresholds for cutaneous vasodilation in the forearm and dorsal hand and for sweating in the forearm and chest. These findings suggest that short-term heat acclimation does not alter the spontaneous baroreflex control of HR during heat stress, although it induces adaptive change of the heat dissipation response in nonglabrous skin. SN - 8750-7587 UR - https://www.unboundmedicine.com/medline/citation/12794028/Heat_acclimation_increases_skin_vasodilation_and_sweating_but_not_cardiac_baroreflex_responses_in_heat_stressed_humans_ L2 - https://journals.physiology.org/doi/10.1152/japplphysiol.00063.2003?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -