title: Do nitric oxide synthase and cyclooxygenase contribute to the heat loss responses in older males exercising in the heat?
abstract: This study evaluated the separate and combined roles of nitric oxide synthase (NOS) and cyclooxygenase (COX) in forearm sweating and cutaneous vasodilatation in older adults during intermittent exercise in the heat. Twelve healthy older (62 ± 7 years) males performed two 30 min cycling bouts at a fixed rate of metabolic heat production (400 W) in the heat (35°C, 20% relative humidity). The exercise bouts were followed by 20 and 40 min of recovery, respectively. Forearm sweat rate (ventilated capsule) and cutaneous vascular conductance (CVC, laser Doppler perfusion units/mean arterial pressure) were evaluated at four skin sites that were continuously perfused via intradermal microdialysis with: (1) lactated Ringer solution (Control), (2) 10 mm ketorolac (non-selective COX inhibitor), (3) 10 mm N(G) -nitro-l-arginine methyl ester (l-NAME; non-selective NOS inhibitor) or (4) a combination of 10 mm ketorolac + 10 mm l-NAME. Sweating was not different between the four sites during either exercise bout (main effect P = 0.92) (average of last 5 min of second exercise, Control, 0.80 ± 0.06; ketorolac, 0.77 ± 0.09; l-NAME, 0.74 ± 0.07; ketorolac + l-NAME, 0.77 ± 0.09 mg min(-1) cm(-2) ). During both exercise bouts, relative to CVC evaluated at the Control site (average of last 5 min of second exercise, 69 ± 6%max), CVC was similar at the ketorolac site (P = 0.62; 66 ± 4%max) whereas it was attenuated to a similar extent at both the l-NAME (49 ± 8%max) and ketorolac + l-NAME (54 ± 8%max) sites (both P < 0.05). Thus, we demonstrate that NOS and COX are not functionally involved in forearm sweating whereas only NOS contributes to forearm cutaneous vasodilatation in older adults during intermittent exercise in the heat.
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.
authors.forename: Naoto
authors.initials: N
authors.lastname: Fujii
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Paull
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Meade
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.
authors.forename: Ryan
authors.initials: R
authors.lastname: McGinn
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.
authors.forename: Jill M
authors.initials: JM
authors.lastname: Stapleton
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.
authors.forename: Pegah
authors.initials: P
authors.lastname: Akbari
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, ON, Canada.|Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada.
authors.forename: Glen P
authors.initials: GP
authors.lastname: Kenny
mesh_terms: D000368:Aged; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology*; D015444:Exercise; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008875:Middle Aged; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D012867:Skin / Q000098:blood supply; D013546:Sweating / Q000187:drug effects*; D022722:Thermogenesis / Q000187:drug effects*; D014664:Vasodilation
chemical_list: D016861:Cyclooxygenase Inhibitors; D019001:Nitric Oxide Synthase; D011451:Prostaglandin-Endoperoxide Synthases
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