The effect of endothelin A and B receptor blockade on cutaneous vascular and sweating responses in young males during and following exercise in the heat

During exercise, cutaneous vasodilation and sweating responses occur, whereas these responses rapidly decrease during postexercise recovery. We hypothesized that the activation of endothelin A (ETA) receptors, but not endothelin B (ETB) receptors, attenuate cutaneous vasodilation during high-intensity exercise and contribute to the subsequent postexercise suppression of cutaneous vasodilation. We also hypothesized that both receptors increase sweating during and following high-intensity exercise. Eleven males (24 ± 4 years) performed an intermittent cycling protocol consisting of two 30-min bouts of moderate- (40% VO_2peak) and high- (75% VO_2peak) intensity exercise in the heat (35°C), each separated by a 20- and 40-min recovery period, respectively. Cutaneous vascular conductance (CVC) and sweat rate were evaluated at four intradermal microdialysis skin sites: 1) lactated Ringer (Control), 2) 500 nM BQ123 (a selective ETA receptor blocker), 3) 300 nM BQ788 (a selective ETB receptor blocker), or 4) a combination of BQ123+BQ788. There were no between-site differences in CVC during each exercise bout (all P > 0.05), however, CVC following high-intensity exercise was greater at BQ123 (56 ± 9 %max) and BQ123+BQ788 (55 ± 14 %max) sites relative to the Control site (43 ± 12 %max) (all P ≤ 0.05). Sweat rate did not differ between sites throughout the protocol (all P > 0.05). We show that neither ETA nor ETB receptors modulate cutaneous vasodilation and sweating responses during and following moderate- and high-intensity exercise in the heat, with the exception that ETA receptors may partly contribute to the suppression of cutaneous vasodilation following high-intensity exercise.

from Physiology via xlomafota13 on Inoreader http://ift.tt/2e0wURe
via IFTTT