title: Exploring the mechanisms underpinning sweating: the development of a specialized ventilated capsule for use with intradermal microdialysis.
abstract: Many studies have aimed to identify the controllers of sweating using ventilated capsules with intradermal microdialysis. It is unclear, however, if the surface area covered by the capsule influences the observed response as a result of differences in the number of sweat glands affected by the infused pharmacological agent relative to the total glands captured by the capsule. We evaluated the area of skin perfused with agents delivered via microdialysis. Thereafter, we developed a specialized sweat capsule (1.1 cm(2)) and compared the sweating response with a classic capsule (2.8 cm(2)). InProtocol 1(n = 6), methacholine was delivered to forearm skin in a dose-dependent manner (1-2000 mmol L(-1)). The area of activated sweat glands was assessed via the modified iodine-paper technique. InProtocol 2(n = 6), the area of inhibited sweat glands induced by ouabain and atropine was assessed during moderate-intensity cycling. Marked variability in the affected skin area was observed (0.9 ± 0.4 to 5.2 ± 1.1 cm(2)). InProtocol 3(n = 6), we compared the attenuation in local sweat rate (LSR) induced by atropine between the new and classic capsule during moderate-intensity cycling. Atropine attenuated sweating as assessed using the new (control: 0.87 ± 0.23 mg min(-1) cm(-2)vs. atropine: 0.54 ± 0.22 mg min(-1) cm(-2);P < 0.01) and classic (control: 0.85 ± 0.33 mg min(-1) cm(-2)vs. atropine: 0.60 ± 0.26 mg min(-1) cm(-2);P = 0.05) capsule designs. Importantly, responses did not differ between capsule designs (P = 0.23). These findings provide critical information regarding the skin surface area perfused by microdialysis and suggest that use of a larger capsule does not alter the mechanistic insight into the sweating response gained when using microdialysis.
authors.affiliation: Human and Environmental Physiology Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Meade
authors.affiliation: Human and Environmental Physiology Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Louie
authors.affiliation: Human and Environmental Physiology Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Martin P
authors.initials: MP
authors.lastname: Poirier
authors.affiliation: Human and Environmental Physiology Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Ryan
authors.initials: R
authors.lastname: McGinn
authors.affiliation: Human and Environmental Physiology Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Naoto
authors.initials: N
authors.lastname: Fujii
authors.affiliation: Human and Environmental Physiology Research Unit, Faculty of Health Sciences, University of Ottawa, Ottawa, Ontario, Canada gkenny@uottawa.ca.
authors.forename: Glen P
authors.initials: GP
authors.lastname: Kenny
mesh_terms: D000279:Administration, Cutaneous; D000328:Adult; D001285:Atropine / Q000008:administration & dosage; D001642:Bicycling; D004305:Dose-Response Relationship, Drug; D004867:Equipment Design; D005260:Female; D005542:Forearm; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000008:administration & dosage; D017551:Microdialysis / Q000295:instrumentation*; D018721:Muscarinic Agonists / Q000008:administration & dosage; D018727:Muscarinic Antagonists / Q000008:administration & dosage; D010042:Ouabain / Q000008:administration & dosage; D015203:Reproducibility of Results; D013542:Sweat / Q000378:metabolism*; D013545:Sweat Glands / Q000187:drug effects / Q000378:metabolism*; D013546:Sweating / Q000187:drug effects; D055815:Young Adult
chemical_list: D018721:Muscarinic Agonists; D018727:Muscarinic Antagonists; D016210:Methacholine Chloride; D010042:Ouabain; D001285:Atropine
keywords: Heat loss; heat stress; sweat rate; thermoregulation