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 P˂0.01). 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.
- cutaneous vasodilation
- Copyright © 2017, American Journal of Physiology-Regulatory, Integrative and Comparative Physiology