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Effects of beta(2)-agonists on force during and following anoxia in rat extensor digitorum longus muscle
Aarhus Univ, Dept Biomed, DK-8000 Aarhus C, Denmark.
Aarhus Univ, Dept Biomed, DK-8000 Aarhus C, Denmark.
Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. (NVC)
Aarhus Univ, Dept Biomed, DK-8000 Aarhus C, Denmark.
2012 (English)In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 112, no 12, 2057-2067 p.Article in journal (Refereed) Published
Abstract [en]

Fredsted A, Gissel H, Ortenblad N, Clausen T. Effects of beta(2)-agonists on force during and following anoxia in rat extensor digitorum longus muscle. J Appl Physiol 112: 2057-2067, 2012. First published April 5, 2012; doi:10.1152/japplphysiol.01558.2011.-Electrical stimulation of isolated muscles may lead to membrane depolarization, gain of Na+, loss of K+ and fatigue. These effects can be counteracted with beta(2)-agonists possibly via activation of the Na+-K+ pumps. Anoxia induces loss of force; however, it is not known whether beta(2)-agonists affect force and ion homeostasis in anoxic muscles. In the present study isolated rat extensor digitorum longus (EDL) muscles exposed to anoxia showed a considerable loss of force, which was markedly reduced by the beta(2)-agonists salbutamol (10(-6) M) and terbutaline (10(-6) M). Intermittent stimulation (15-30 min) clearly increased loss of force during anoxia and reduced force recovery during reoxygenation. The beta(2)-agonists salbutamol (10(-7)-10(-5) M) and salmeterol (10(-6) M) improved force development during anoxia (25%) and force recovery during reoxygenation (55-262%). The effects of salbutamol on force recovery were prevented by blocking the Na+-K+ pumps with ouabain or by blocking glycolysis with 2-deoxyglucose. Dibutyryl cAMP (1 mM) or theophylline (1 mM) also improved force recovery remarkably. In anoxic muscles, salbutamol decreased intracellular Na+ and increased Rb-86 uptake and K+ content, indicating stimulation of the Na+-K+ pumps. In fatigued muscles salbutamol induced recovery of excitability. Thus beta(2)-agonists reduce the anoxia-induced loss of force, leading to partial force recovery. These data strongly suggest that this effect is mediated by cAMP stimulation of the Na+-K+ pumps and that it is not related to recovery of energy status (PCr, ATP, lactate).

Place, publisher, year, edition, pages
2012. Vol. 112, no 12, 2057-2067 p.
Keyword [en]
contractility, salbutamol, theophylline, Na+-K+ pumps
National Category
Sport and Fitness Sciences
Identifiers
URN: urn:nbn:se:miun:diva-17069DOI: 10.1152/japplphysiol.01558.2011ISI: 000305422100014Scopus ID: 2-s2.0-84862533007OAI: oai:DiVA.org:miun-17069DiVA: diva2:557959
Available from: 2012-10-01 Created: 2012-09-26 Last updated: 2015-06-30Bibliographically approved

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