Individual variations in nitric oxide synthase-dependent sweating in young and older males during exercise in the heat: role of aerobic power.
We evaluated the association between aerobic power (defined by peak oxygen consumption;VO2peak) and the contribution of nitric oxide synthase (NOS) to the sweating response in young and older individuals during exercise in the heat. Data from 44 young (24 ± 1 years) and 48 older (61 ± 2 years) males with mean VO2peakof 47.8 ± 2.4 (range, 28.0-62.3) and 39.1 ± 2.3 (range, 26.4-55.7) mLO2kg-1min-1, respectively, were compiled from our prior studies. Participants performed two 15- to 30-min bouts of exercise at a fixed rate of metabolic heat production of 400 or 500 W, each separated by 15-20 min recovery in the heat (35°C, relative humidity of 20%). Forearm sweat rate (ventilated capsule technique) was measured at two skin sites that were continuously and simultaneously administered with lactated Ringers solution (Control) or 10 mmol/LNG-nitro-L-arginine methyl ester (L-NAME, nonselective NOS inhibitor) via intradermal microdialysis. Sweat rate during the final 5 min of each exercise bout was lower withL-NAME compared to the Control in both groups (allP<0.05). The magnitude of the attenuation in sweat rate induced byL-NAME compared to the Control was not correlated withVO2peak(allP≥0.46) while this attenuation was negatively correlated with the sweat rate at the Control in both groups and in both exercise bouts (allP<0.01,R≤ -0.43). These results suggest that NOS-dependent sweating is not associated with aerobic powerper se, while it becomes evident in individuals who produce larger sweat rates during exercise irrespective of age.
Laboratory for Exercise and Environmental Physiology, Faculty of Education, Niigata University, Niigata, Japan.|Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada.
Tatsuro
T
Amano
Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada.|Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Japan.
Naoto
N
Fujii
Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada.
Jeffrey C
JC
Louie
Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada.
Robert D
RD
Meade
Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada gkenny@uottawa.ca.
Glen P
GP
Kenny
D000328:Adult; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015444:Exercise / Q000502:physiology*; D005542:Forearm / Q000098:blood supply; D006358:Hot Temperature; D006801:Humans; D007206:Individuality; D008297:Male; D008875:Middle Aged; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology*; D012039:Regional Blood Flow / Q000187:drug effects; D013546:Sweating / Q000187:drug effects / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects; D055815:Young Adult
D004791:Enzyme Inhibitors; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester
Aerobic power; aging; eccrine sweat glands; exercise training; nitric oxide