title: The roles of KCa, KATP, and KVchannels in regulating cutaneous vasodilation and sweating during exercise in the heat.
abstract: We recently showed the varying roles of Ca2+-activated (KCa), ATP-sensitive (KATP), and voltage-gated (KV) K+channels in regulating cholinergic cutaneous vasodilation and sweating in normothermic conditions. However, it is unclear whether the respective contributions of these K+channels remain intact during dynamic exercise in the heat. Eleven young (23 ± 4 yr) men completed a 30-min exercise bout at a fixed rate of metabolic heat production (400 W) followed by a 40-min recovery period in the heat (35°C, 20% relative humidity). Cutaneous vascular conductance (CVC) and local sweat rate were assessed at four forearm skin sites perfused via intradermal microdialysis with:1) lactated Ringer solution (control);2) 50 mM tetraethylammonium (nonspecific KCachannel blocker);3) 5 mM glybenclamide (selective KATPchannel blocker); or4) 10 mM 4-aminopyridine (nonspecific KVchannel blocker). Responses were compared at baseline and at 10-min intervals during and following exercise. KCachannel inhibition resulted in greater CVC versus control at end exercise (P= 0.04) and 10 and 20 min into recovery (bothP< 0.01). KATPchannel blockade attenuated CVC compared with control during baseline (P= 0.04), exercise (allP≤ 0.04), and 10 min into recovery (P= 0.02). No differences in CVC were observed with KVchannel inhibition during baseline (P= 0.15), exercise (allP≥ 0.06), or recovery (allP≥ 0.14). With the exception of KVchannel inhibition augmenting sweating during baseline (P= 0.04), responses were similar to control with all K+channel blockers during each time period (allP≥ 0.07). We demonstrated that KCaand KATPchannels contribute to the regulation of cutaneous vasodilation during rest and/or exercise and recovery in the heat.
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada; and.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Louie
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada; and.|Institute of Health and Sports Sciences, University of Tsukuba, Tsukuba, Japan.
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, Ontario, Canada; and.
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, Ontario, Canada; and.
authors.forename: Brendan D
authors.initials: BD
authors.lastname: McNeely
authors.affiliation: Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada; and gkenny@uottawa.ca.
authors.forename: Glen P
authors.initials: GP
authors.lastname: Kenny
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D018869:Heat-Shock Response / Q000502:physiology*; D006801:Humans; D054086:KATP Channels / Q000378:metabolism; D008297:Male; D015221:Potassium Channels / Q000378:metabolism*; D024681:Potassium Channels, Calcium-Activated / Q000378:metabolism; D024642:Potassium Channels, Voltage-Gated / Q000378:metabolism; D012039:Regional Blood Flow / Q000502:physiology; D012867:Skin / Q000098:blood supply; D012879:Skin Physiological Phenomena; D013546:Sweating / Q000502:physiology*; D014664:Vasodilation / Q000502:physiology*; D055815:Young Adult
chemical_list: D054086:KATP Channels; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D024642:Potassium Channels, Voltage-Gated
keywords: KATP; KCa; KV; cutaneous vasodilation; exercise; heat loss; hyperpolarization; sweat