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Effects of concentric and eccentric contractions on phosphorylation of MAPK erk1/2 and MAPK p38 in isolated rat skeletal muscle
Author(s) -
Wretman Charlott,
Lionikas Arimantas,
Widegren Ulrika,
Lännergren Jan,
Westerblad Håkan,
Henriksson Jan
Publication year - 2001
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2001.00155.x
Subject(s) - phosphorylation , mapk/erk pathway , p38 mitogen activated protein kinases , kinase , protein kinase a , medicine , contraction (grammar) , skeletal muscle , eccentric , extracellular , endocrinology , muscle contraction , chemistry , biology , biochemistry , microbiology and biotechnology , physics , quantum mechanics
1 Exercise and contractions of isolated skeletal muscle induce phosphorylation of mitogen‐activated protein kinases (MAPKs) by undefined mechanisms. The aim of the present study was to determine exercise‐related triggering factors for the increased phosphorylation of MAPKs in isolated rat extensor digitorum longus (EDL) muscle. 2 Concentric or eccentric contractions, or mild or severe passive stretches were used to discriminate between effects of metabolic/ionic and mechanical alterations on phosphorylation of two MAPKs: extracellular signal‐regulated kinase 1 and 2 (MAPK erk1/2 ) and stress‐activated protein kinase p38 (MAPK p38 ). 3 Concentric contractions induced a 5‐fold increase in MAPK erk1/2 phosphorylation. Application of the antioxidants N‐ acetylcysteine (20 mM) or dithiothreitol (5 mM) suppressed concentric contraction‐induced increase in MAPK erk1/2 phosphorylation. Mild passive stretches of the muscle increased MAPK erk1/2 phosphorylation by 1.8‐fold, whereas the combination of acidosis and passive stretches resulted in a 2.8‐fold increase. Neither concentric contractions, nor mild stretches nor acidosis significantly affected phosphorylation of MAPK p38 . 4 High force applied upon muscle by means of either eccentric contractions or severe passive stretches resulted in 5.7‐ and 9.5‐fold increases of phosphorylated MAPK erk1/2 , respectively, whereas phosphorylation of MAPK p38 increased by 7.6‐ and 1.9‐fold (not significant), respectively. 5 We conclude that in isolated rat skeletal muscle an increase in phosphorylation of both MAPK erk1/2 and MAPK p38 is induced by mechanical alterations, whereas contraction‐related metabolic/ionic changes (reactive oxygen species and acidosis) cause increased phosphorylation of MAPK erk1/2 only. Thus, contraction‐induced phosphorylation can be explained by the combined action of increased production of reactive oxygen species, acidification and mechanical perturbations for MAPK erk1/2 and by high mechanical stress for MAPK p38 .