title: Differential activation of mitogen-activated protein kinase signalling pathways by isometric contractions in isolated slow- and fast-twitch rat skeletal muscle.
abstract: Activation of mitogen-activated protein (MAP) kinases has been implicated in the signal transduction pathways linking exercise to adaptive changes of muscle protein expression. In the present study, we investigated whether contractions of isolated muscles induced phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and p38 MAPK in a fibre-type dependent manner. Slow-twitch (soleus) and fast-twitch (epitrochlearis, extensor digitorum longus) rat skeletal muscles were exposed to intermittent tetanic stimulation. Compared with the contralateral non-stimulated muscle, contractions increased ERK1/2 phosphorylation to the same extent in fast- and slow-twitch muscles. Significant increase in phosphorylation of p38 MAPK was observed in the fast-twitch muscles only. The total amount of ERK1/2 and p38 MAPK proteins was higher in the slow-twitch soleus muscle. In conclusion, MAP kinase signalling pathways are differentially activated and expressed in slow- and fast-twitch muscles. In addition, this activation is owing to muscle contraction per se and do not demand additional external influence.
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: C
authors.initials: C
authors.lastname: Wretman
authors.forename: U
authors.initials: U
authors.lastname: Widegren
authors.forename: A
authors.initials: A
authors.lastname: Lionikas
authors.forename: H
authors.initials: H
authors.lastname: Westerblad
authors.forename: J
authors.initials: J
authors.lastname: Henriksson
mesh_terms: D000818:Animals; D007537:Isometric Contraction / Q000502:physiology*; D020935:MAP Kinase Signaling System / Q000502:physiology; D008297:Male; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism*; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000502:physiology; D010766:Phosphorylation; D051381:Rats; D017208:Rats, Wistar; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases