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Isoproterenol enhances force production in mouse glycolytic and oxidative muscle via separate mechanisms.
Pflugers Arch. 2019 10; 471(10):1305-1316.PA

Abstract

Fight or flight is a biologic phenomenon that involves activation of β-adrenoceptors in skeletal muscle. However, how force generation is enhanced through adrenergic activation in different muscle types is not fully understood. We studied the effects of isoproterenol (ISO, β-receptor agonist) on force generation and energy metabolism in isolated mouse soleus (SOL, oxidative) and extensor digitorum longus (EDL, glycolytic) muscles. Muscles were stimulated with isometric tetanic contractions and analyzed for metabolites and phosphorylase activity. Under conditions of maximal force production, ISO enhanced force generation markedly more in SOL (22%) than in EDL (8%). Similarly, during a prolonged tetanic contraction (30 s for SOL and 10 s for EDL), ISO-enhanced the force × time integral more in SOL (25%) than in EDL (3%). ISO induced marked activation of phosphorylase in both muscles in the basal state, which was associated with glycogenolysis (less in SOL than in EDL), and in EDL only, a significant decrease (16%) in inorganic phosphate (Pi). ATP turnover during sustained contractions (1 s EDL, 5 s SOL) was not affected by ISO in EDL, but essentially doubled in SOL. Under conditions of maximal stimulation, ISO has a minor effect on force generation in EDL that is associated with a decrease in Pi, whereas ISO has a marked effect on force generation in SOL that is associated with an increase in ATP turnover. Thus, phosphorylase functions as a phosphate trap in ISO-mediated force enhancement in EDL and as a catalyzer of ATP supply in SOL.

Authors+Show Affiliations

Åstrand Laboratory of Work Physiology, Swedish School of Sport and Health Sciences, GIH, Box 5626, S-114 86, Stockholm, Sweden.Åstrand Laboratory of Work Physiology, Swedish School of Sport and Health Sciences, GIH, Box 5626, S-114 86, Stockholm, Sweden. abram.katz@gih.se.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

31451903

Citation

Blackwood, Sarah J., and Abram Katz. "Isoproterenol Enhances Force Production in Mouse Glycolytic and Oxidative Muscle Via Separate Mechanisms." Pflugers Archiv : European Journal of Physiology, vol. 471, no. 10, 2019, pp. 1305-1316.
Blackwood SJ, Katz A. Isoproterenol enhances force production in mouse glycolytic and oxidative muscle via separate mechanisms. Pflugers Arch. 2019;471(10):1305-1316.
Blackwood, S. J., & Katz, A. (2019). Isoproterenol enhances force production in mouse glycolytic and oxidative muscle via separate mechanisms. Pflugers Archiv : European Journal of Physiology, 471(10), 1305-1316. https://doi.org/10.1007/s00424-019-02304-0
Blackwood SJ, Katz A. Isoproterenol Enhances Force Production in Mouse Glycolytic and Oxidative Muscle Via Separate Mechanisms. Pflugers Arch. 2019;471(10):1305-1316. PubMed PMID: 31451903.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Isoproterenol enhances force production in mouse glycolytic and oxidative muscle via separate mechanisms. AU - Blackwood,Sarah J, AU - Katz,Abram, Y1 - 2019/08/21/ PY - 2019/07/22/received PY - 2019/08/13/accepted PY - 2019/07/22/revised PY - 2019/8/28/pubmed PY - 2019/8/28/medline PY - 2019/8/28/entrez KW - Fatigue KW - Force KW - Isoproterenol KW - Metabolites KW - Muscle KW - Phosphorylase SP - 1305 EP - 1316 JF - Pflugers Archiv : European journal of physiology JO - Pflugers Arch. VL - 471 IS - 10 N2 - Fight or flight is a biologic phenomenon that involves activation of β-adrenoceptors in skeletal muscle. However, how force generation is enhanced through adrenergic activation in different muscle types is not fully understood. We studied the effects of isoproterenol (ISO, β-receptor agonist) on force generation and energy metabolism in isolated mouse soleus (SOL, oxidative) and extensor digitorum longus (EDL, glycolytic) muscles. Muscles were stimulated with isometric tetanic contractions and analyzed for metabolites and phosphorylase activity. Under conditions of maximal force production, ISO enhanced force generation markedly more in SOL (22%) than in EDL (8%). Similarly, during a prolonged tetanic contraction (30 s for SOL and 10 s for EDL), ISO-enhanced the force × time integral more in SOL (25%) than in EDL (3%). ISO induced marked activation of phosphorylase in both muscles in the basal state, which was associated with glycogenolysis (less in SOL than in EDL), and in EDL only, a significant decrease (16%) in inorganic phosphate (Pi). ATP turnover during sustained contractions (1 s EDL, 5 s SOL) was not affected by ISO in EDL, but essentially doubled in SOL. Under conditions of maximal stimulation, ISO has a minor effect on force generation in EDL that is associated with a decrease in Pi, whereas ISO has a marked effect on force generation in SOL that is associated with an increase in ATP turnover. Thus, phosphorylase functions as a phosphate trap in ISO-mediated force enhancement in EDL and as a catalyzer of ATP supply in SOL. SN - 1432-2013 UR - https://www.unboundmedicine.com/medline/citation/31451903/Isoproterenol_enhances_force_production_in_mouse_glycolytic_and_oxidative_muscle_via_separate_mechanisms L2 - https://dx.doi.org/10.1007/s00424-019-02304-0 DB - PRIME DP - Unbound Medicine ER -
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