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Epinephrine augments posttetanic potentiation in mouse skeletal muscle with and without myosin phosphorylation

Sympathetic tone may influence force potentiation, that is, the stimulation‐induced increase in skeletal muscle mechanical function associated with myosin phosphorylation, although the mechanism for this effect remains unknown. The purpose of this study was to examine the influence of epinephrine on...

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Autores principales: Morris, Stephen Roy, Gittings, William, Vandenboom, Rene
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5931225/
https://www.ncbi.nlm.nih.gov/pubmed/29718592
http://dx.doi.org/10.14814/phy2.13690
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author Morris, Stephen Roy
Gittings, William
Vandenboom, Rene
author_facet Morris, Stephen Roy
Gittings, William
Vandenboom, Rene
author_sort Morris, Stephen Roy
collection PubMed
description Sympathetic tone may influence force potentiation, that is, the stimulation‐induced increase in skeletal muscle mechanical function associated with myosin phosphorylation, although the mechanism for this effect remains unknown. The purpose of this study was to examine the influence of epinephrine on concentric twitch force potentiation of wild‐type and skeletal myosin light‐chain kinase devoid mouse muscle (skMLCK (−/−)). To this end, concentric twitch force was assessed before and after a potentiating stimulus (PS) to determine the peak and the duration of potentiation in the absence (−EPI) and presence (+EPI) of 1 μmol/L epinephrine in both genotypes. Twitch force of wild‐type and skMLCK (−/−) muscles was increased by up to 31 and 35% and 18 and 23% in the −EPI and EPI conditions, respectively (all data n = 8, P < 0.05). In wild‐type muscles, the PS increased RLC phosphorylation from 0.14 ± 0.05 (rest) to 0.66 ± 0.08 mol phos mol RLC; by 480 sec RLC phosphorylation had returned to baseline (all data n = 4 each time point, P < 0.05). Neither resting nor peak levels of RLC phosphorylation were altered by +EPI, although the duration of RLC phosphorylation was prolonged. In skMLCK (−/−) muscles, RLC phosphorylation was not elevated above constituent levels by stimulation in either the −EPI or +EPI condition. Thus, given the similarity in potentiation responses between genotypes our data suggest that the influence of epinephrine on potentiation was independent of skMLCK catalyzed phosphorylation of the RLC, although the clinical significance of this pathway for skeletal muscle function remains to be identified.
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spelling pubmed-59312252018-05-09 Epinephrine augments posttetanic potentiation in mouse skeletal muscle with and without myosin phosphorylation Morris, Stephen Roy Gittings, William Vandenboom, Rene Physiol Rep Original Research Sympathetic tone may influence force potentiation, that is, the stimulation‐induced increase in skeletal muscle mechanical function associated with myosin phosphorylation, although the mechanism for this effect remains unknown. The purpose of this study was to examine the influence of epinephrine on concentric twitch force potentiation of wild‐type and skeletal myosin light‐chain kinase devoid mouse muscle (skMLCK (−/−)). To this end, concentric twitch force was assessed before and after a potentiating stimulus (PS) to determine the peak and the duration of potentiation in the absence (−EPI) and presence (+EPI) of 1 μmol/L epinephrine in both genotypes. Twitch force of wild‐type and skMLCK (−/−) muscles was increased by up to 31 and 35% and 18 and 23% in the −EPI and EPI conditions, respectively (all data n = 8, P < 0.05). In wild‐type muscles, the PS increased RLC phosphorylation from 0.14 ± 0.05 (rest) to 0.66 ± 0.08 mol phos mol RLC; by 480 sec RLC phosphorylation had returned to baseline (all data n = 4 each time point, P < 0.05). Neither resting nor peak levels of RLC phosphorylation were altered by +EPI, although the duration of RLC phosphorylation was prolonged. In skMLCK (−/−) muscles, RLC phosphorylation was not elevated above constituent levels by stimulation in either the −EPI or +EPI condition. Thus, given the similarity in potentiation responses between genotypes our data suggest that the influence of epinephrine on potentiation was independent of skMLCK catalyzed phosphorylation of the RLC, although the clinical significance of this pathway for skeletal muscle function remains to be identified. John Wiley and Sons Inc. 2018-05-02 /pmc/articles/PMC5931225/ /pubmed/29718592 http://dx.doi.org/10.14814/phy2.13690 Text en © 2018 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society. This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Research
Morris, Stephen Roy
Gittings, William
Vandenboom, Rene
Epinephrine augments posttetanic potentiation in mouse skeletal muscle with and without myosin phosphorylation
title Epinephrine augments posttetanic potentiation in mouse skeletal muscle with and without myosin phosphorylation
title_full Epinephrine augments posttetanic potentiation in mouse skeletal muscle with and without myosin phosphorylation
title_fullStr Epinephrine augments posttetanic potentiation in mouse skeletal muscle with and without myosin phosphorylation
title_full_unstemmed Epinephrine augments posttetanic potentiation in mouse skeletal muscle with and without myosin phosphorylation
title_short Epinephrine augments posttetanic potentiation in mouse skeletal muscle with and without myosin phosphorylation
title_sort epinephrine augments posttetanic potentiation in mouse skeletal muscle with and without myosin phosphorylation
topic Original Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5931225/
https://www.ncbi.nlm.nih.gov/pubmed/29718592
http://dx.doi.org/10.14814/phy2.13690
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