title: The effect of endothelin A and B receptor blockade on cutaneous vascular and sweating responses in young men during and following exercise in the heat.
abstract: During exercise, cutaneous vasodilation and sweating responses occur, whereas these responses rapidly decrease during postexercise recovery. We hypothesized that the activation of endothelin A (ETA) receptors, but not endothelin B (ETB) receptors, attenuate cutaneous vasodilation during high-intensity exercise and contribute to the subsequent postexercise suppression of cutaneous vasodilation. We also hypothesized that both receptors increase sweating during and following high-intensity exercise. Eleven men (24 ± 4 yr) performed an intermittent cycling protocol consisting of two 30-min bouts of moderate- (40% V̇o2peak) and high-intensity (75% V̇o2peak) exercise in the heat (35°C), each separated by a 20- and 40-min recovery period, respectively. Cutaneous vascular conductance (CVC) and sweat rate were evaluated at four intradermal microdialysis skin sites: 1) lactated Ringer (control), 2) 500 nM BQ123 (a selective ETAreceptor blocker), 3) 300 nM BQ788 (a selective ETBreceptor blocker), or 4) a combination of BQ123 + BQ788. There were no between-site differences in CVC during each exercise bout (all P > 0.05); however, CVC following high-intensity exercise was greater at BQ123 (56 ± 9%max) and BQ123 + BQ788 (55 ± 14%max) sites relative to the control site (43 ± 12%max) (all P ≤ 0.05). Sweat rate did not differ between sites throughout the protocol (all P > 0.05). We show that neither ETAnor ETBreceptors modulate cutaneous vasodilation and sweating responses during and following moderate- and high-intensity exercise in the heat, with the exception that ETAreceptors may partly contribute to the suppression of cutaneous vasodilation following high-intensity exercise.
authors.affiliation: Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada.
authors.forename: Naoto
authors.initials: N
authors.lastname: Fujii
authors.affiliation: Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada.
authors.forename: Maya S
authors.initials: MS
authors.lastname: Singh
authors.affiliation: Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada.
authors.forename: Lyra
authors.initials: L
authors.lastname: Halili
authors.affiliation: Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Louie
authors.affiliation: Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada gkenny@uottawa.ca.
authors.forename: Glen P
authors.initials: GP
authors.lastname: Kenny
mesh_terms: D000328:Adult; D065130:Endothelin A Receptor Antagonists / Q000494:pharmacology*; D065131:Endothelin B Receptor Antagonists / Q000494:pharmacology*; D015444:Exercise / Q000502:physiology*; D006358:Hot Temperature; D006801:Humans; D008297:Male; D044022:Receptor, Endothelin A / Q000378:metabolism; D044023:Receptor, Endothelin B / Q000378:metabolism; D012867:Skin / Q000098:blood supply* / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D013546:Sweating / Q000187:drug effects* / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D055815:Young Adult
chemical_list: D065130:Endothelin A Receptor Antagonists; D065131:Endothelin B Receptor Antagonists; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B
keywords: ET-1; endothelial cell; endothelium-derived contracting factors; microcirculation