The roles of KCa, KATP, and KV channels in regulating cutaneous vasodilation and sweating during exercise in the heat
AJP Regulatory Integrative and Comparative Physiology
Published online on March 02, 2017
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 years) males 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 either: 1) lactated Ringer's solution (Control), 2) 50mM tetraethylammonium (non-specific KCa channel blocker), 3) 5mM glybenclamide (selective KATP channel blocker), or 4) 10mM 4-aminopyridine (non-specific 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 P0.01). KATP channel blockade attenuated CVC compared to 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.