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Divergent roles of plasma osmolality and the baroreflex on sweating and skin blood flow.
Am J Physiol Regul Integr Comp Physiol. 2012 Mar 01; 302(5):R634-42.AJ

Abstract

Plasma hyperosmolality and baroreceptor unloading have been shown to independently influence the heat loss responses of sweating and cutaneous vasodilation. However, their combined effects remain unresolved. On four separate occasions, eight males were passively heated with a liquid-conditioned suit to 1.0°C above baseline core temperature during a resting isosmotic state (infusion of 0.9% NaCl saline) with (LBNP) and without (CON) application of lower-body negative pressure (-40 cmH2O) and during a hyperosmotic state (infusion of 3.0% NaCl saline) with (LBNP + HYP) and without (HYP) application of lower-body negative pressure. Forearm sweat rate (ventilated capsule) and skin blood flow (laser-Doppler), as well as core (esophageal) and mean skin temperatures, were measured continuously. Plasma osmolality increased by ∼10 mosmol/kgH2O during HYP and HYP + LBNP conditions, whereas it remained unchanged during CON and LBNP (P ≤ 0.05). The change in mean body temperature (0.8 × core temperature + 0.2 × mean skin temperature) at the onset threshold for increases in cutaneous vascular conductance (CVC) was significantly greater during LBNP (0.56 ± 0.24°C) and HYP (0.69 ± 0.36°C) conditions compared with CON (0.28 ± 0.23°C, P ≤ 0.05). Additionally, the onset threshold for CVC during LBNP + HYP (0.88 ± 0.33°C) was significantly greater than CON and LBNP conditions (P ≤ 0.05). In contrast, onset thresholds for sweating were not different during LBNP (0.50 ± 0.18°C) compared with CON (0.46 ± 0.26°C, P = 0.950) but were elevated (P ≤ 0.05) similarly during HYP (0.91 ± 0.37°C) and LBNP + HYP (0.94 ± 0.40°C). Our findings show an additive effect of hyperosmolality and baroreceptor unloading on the onset threshold for increases in CVC during whole body heat stress. In contrast, the onset threshold for sweating during heat stress was only elevated by hyperosmolality with no effect of the baroreflex.

Authors+Show Affiliations

Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Canada.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

22170619

Citation

Lynn, Aaron G., et al. "Divergent Roles of Plasma Osmolality and the Baroreflex On Sweating and Skin Blood Flow." American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, vol. 302, no. 5, 2012, pp. R634-42.
Lynn AG, Gagnon D, Binder K, et al. Divergent roles of plasma osmolality and the baroreflex on sweating and skin blood flow. Am J Physiol Regul Integr Comp Physiol. 2012;302(5):R634-42.
Lynn, A. G., Gagnon, D., Binder, K., Boushel, R. C., & Kenny, G. P. (2012). Divergent roles of plasma osmolality and the baroreflex on sweating and skin blood flow. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, 302(5), R634-42. https://doi.org/10.1152/ajpregu.00411.2011
Lynn AG, et al. Divergent Roles of Plasma Osmolality and the Baroreflex On Sweating and Skin Blood Flow. Am J Physiol Regul Integr Comp Physiol. 2012 Mar 1;302(5):R634-42. PubMed PMID: 22170619.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Divergent roles of plasma osmolality and the baroreflex on sweating and skin blood flow. AU - Lynn,Aaron G, AU - Gagnon,Daniel, AU - Binder,Konrad, AU - Boushel,Robert C, AU - Kenny,Glen P, Y1 - 2011/12/14/ PY - 2011/12/16/entrez PY - 2011/12/16/pubmed PY - 2012/5/4/medline SP - R634 EP - 42 JF - American journal of physiology. Regulatory, integrative and comparative physiology JO - Am. J. Physiol. Regul. Integr. Comp. Physiol. VL - 302 IS - 5 N2 - Plasma hyperosmolality and baroreceptor unloading have been shown to independently influence the heat loss responses of sweating and cutaneous vasodilation. However, their combined effects remain unresolved. On four separate occasions, eight males were passively heated with a liquid-conditioned suit to 1.0°C above baseline core temperature during a resting isosmotic state (infusion of 0.9% NaCl saline) with (LBNP) and without (CON) application of lower-body negative pressure (-40 cmH2O) and during a hyperosmotic state (infusion of 3.0% NaCl saline) with (LBNP + HYP) and without (HYP) application of lower-body negative pressure. Forearm sweat rate (ventilated capsule) and skin blood flow (laser-Doppler), as well as core (esophageal) and mean skin temperatures, were measured continuously. Plasma osmolality increased by ∼10 mosmol/kgH2O during HYP and HYP + LBNP conditions, whereas it remained unchanged during CON and LBNP (P ≤ 0.05). The change in mean body temperature (0.8 × core temperature + 0.2 × mean skin temperature) at the onset threshold for increases in cutaneous vascular conductance (CVC) was significantly greater during LBNP (0.56 ± 0.24°C) and HYP (0.69 ± 0.36°C) conditions compared with CON (0.28 ± 0.23°C, P ≤ 0.05). Additionally, the onset threshold for CVC during LBNP + HYP (0.88 ± 0.33°C) was significantly greater than CON and LBNP conditions (P ≤ 0.05). In contrast, onset thresholds for sweating were not different during LBNP (0.50 ± 0.18°C) compared with CON (0.46 ± 0.26°C, P = 0.950) but were elevated (P ≤ 0.05) similarly during HYP (0.91 ± 0.37°C) and LBNP + HYP (0.94 ± 0.40°C). Our findings show an additive effect of hyperosmolality and baroreceptor unloading on the onset threshold for increases in CVC during whole body heat stress. In contrast, the onset threshold for sweating during heat stress was only elevated by hyperosmolality with no effect of the baroreflex. SN - 1522-1490 UR - https://www.unboundmedicine.com/medline/citation/22170619/Divergent_roles_of_plasma_osmolality_and_the_baroreflex_on_sweating_and_skin_blood_flow_ L2 - http://www.physiology.org/doi/full/10.1152/ajpregu.00411.2011?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -