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Am J Physiol Regul Integr Comp Physiol. 2017 May 1;312(5):R821-R827. doi: 10.1152/ajpregu.00507.2016. Epub 2017 Mar 2.

The roles of KCa, KATP, and KV channels in regulating cutaneous vasodilation and sweating during exercise in the heat.

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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.
Human and Environmental Physiology Research Unit, School of Human Kinetics, University of Ottawa, Ottawa, Ontario, Canada; and


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 KCa channel blocker); 3) 5 mM glybenclamide (selective KATP channel blocker); or 4) 10 mM 4-aminopyridine (nonspecific KV channel blocker). Responses were compared at baseline and at 10-min intervals during and following exercise. KCa channel inhibition resulted in greater CVC versus control at end exercise (P = 0.04) and 10 and 20 min into recovery (both P < 0.01). KATP channel blockade attenuated CVC compared with control during baseline (P = 0.04), exercise (all P ≤ 0.04), and 10 min into recovery (P = 0.02). No differences in CVC were observed with KV channel inhibition during baseline (P = 0.15), exercise (all P ≥ 0.06), or recovery (all P ≥ 0.14). With the exception of KV channel inhibition augmenting sweating during baseline (P = 0.04), responses were similar to control with all K+ channel blockers during each time period (all P ≥ 0.07). We demonstrated that KCa and KATP channels contribute to the regulation of cutaneous vasodilation during rest and/or exercise and recovery in the heat.


KATP; KCa; KV; cutaneous vasodilation; exercise; heat loss; hyperpolarization; sweat

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