caa a22 4500 467940770 CHVBK 20180406153011.0 cr unu---uuuuu 170328e20060401xx s 000 0 eng 10.1007/s00421-005-0128-y doi (NATIONALLICENCE)springer-10.1007/s00421-005-0128-y K+ potentiates hyperosmolarity-induced vasorelaxations in rat skeletal muscle arterioles [Elektronische Daten] [Ine De Clerck, Jean-Louis Pannier, Johan Van de Voorde] Several regulatory mechanisms have been proposed for the exercise hyperemia in skeletal muscles. Since different vasoactive factors might interact during the hyperemic response, we investigated the influence of elevated K+ concentrations on hyperosmolarity (HO)-induced vasorelaxations. Small gluteal rat arteries were isolated and mounted in an organ bath for isometric tension recording. After precontraction with norepinephrine, 20 (S20), 40 (S40) or 60mM (S60) sucrose was added in control conditions (5mM K+; K5) or in the presence of additional 3 (K8) or 5mM (K10) K+. Removal of the endothelium and the addition of ouabain, Ba2+, iberiotoxin or 18-α glycyrrhetinic acid (αGA) were used to study the underlying mechanisms. Sucrose evoked significant concentration-dependent vasorelaxations (S20 15.62±1.61%; S40 26.47±1.71%; S60 43.66±2.50%), which were significantly increased on addition of 3 and 5mM. After removal of the endothelium and in the presence of 5×10−5M αGA, the influence of K+ was significantly blocked but not in the presence of 5×10−5M ouabain. The KIR channel inhibitor Ba2+ and BKCa channel inhibitor iberiotoxin totally abolished the potentiating effect. We conclude that K+ significantly enhances the relaxing effect of HO in gluteal blood vessels. We hypothesize that K+ may stimulate the endothelial KIR channels which elicits the release of a mediator of the BKCa channels. This factor may be transferred through myo-endothelial gap-junctions to the smooth muscle cells where modulation of the BKCa channels sensitizes the arteries for hyperosmolarity-induced relaxations. Springer-Verlag, 2006 Potassium nationallicence Exercise hyperemia nationallicence Hyperosmolarity nationallicence BKCa channels nationallicence De Clerck Ine Department of Movement and Sports Sciences, Ghent University, Watersportlaan 2, 9000, Ghent, Belgium aut Pannier Jean-Louis Department of Movement and Sports Sciences, Ghent University, Watersportlaan 2, 9000, Ghent, Belgium aut Van de Voorde Johan Department of Physiology and Physiopathology, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium aut European Journal of Applied Physiology Springer-Verlag 96/6(2006-04-01), 679-685 1439-6319 96:6<679 2006 96 421 https://doi.org/10.1007/s00421-005-0128-y text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00421-005-0128-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- De Clerck Ine Department of Movement and Sports Sciences, Ghent University, Watersportlaan 2, 9000, Ghent, Belgium aut NATIONALLICENCE 700 1- Pannier Jean-Louis Department of Movement and Sports Sciences, Ghent University, Watersportlaan 2, 9000, Ghent, Belgium aut NATIONALLICENCE 700 1- Van de Voorde Johan Department of Physiology and Physiopathology, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium aut NATIONALLICENCE 773 0- European Journal of Applied Physiology Springer-Verlag 96/6(2006-04-01), 679-685 1439-6319 96:6<679 2006 96 421 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer