Physiological and biochemical characteristics of skeletal muscles in sedentary and active rats
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Laboratory rats are sedentary if housed in conditions where activity is limited. Changes in muscle characteristics with chronic inactivity were investigated by comparing sedentary rats with rats undertaking voluntary wheel running for either 6 or 12 weeks. EDL (type II fibers) and soleus (SOL) muscles (predominantly type I fibers) were examined. When measured within 1–2 h post-running, calcium sensitivity of the contractile apparatus was increased, but only in type II fibers. This increase disappeared when fibers were treated with DTT, indicative of oxidative regulation of the contractile apparatus, and was absent in fibers from rats that had ceased running 24 h prior to experiments. Specific force production was ~ 10 to 25% lower in muscle fibers of sedentary compared to active rats, and excitability of skinned fibers was decreased. Muscle glycogen content was ~ 30% lower and glycogen synthase content ~ 50% higher in SOL of sedentary rats, and in EDL glycogenin was 30% lower. Na+, K+-ATPase α1 subunit density was ~ 20% lower in both EDL and SOL in sedentary rats, and GAPDH content in SOL ~ 35% higher. There were no changes in content of the calcium handling proteins calsequestrin and SERCA, but the content of CSQ-like protein was increased in active rats (by ~ 20% in EDL and 60% in SOL). These findings show that voluntary exercise elicits an acute oxidation-induced increase in Ca2+ sensitivity in type II fibers, and also that there are substantial changes in skeletal muscle characteristics and biochemical processes in sedentary rats.
KeywordsChronic inactivity Voluntary wheel running Single muscle fibers Ca2+-sensitivity Glutathionylation Glycogen MHC composition
This was supported by a National Health and Medical Research Council (Australia) Grant (APP1085331) to GDL and RMM.
- Brocca L, Longa E, Cannavino J, Seynnes O, de Vito G, McPhee J, Narici M, Pellegrino MA, Bottinelli R (2015) Human skeletal muscle fibre contractile properties and proteomic profile: adaptations to 3 weeks of unilateral lower limb suspension and active recovery. J Physiol 593:5361–5385CrossRefPubMedPubMedCentralGoogle Scholar
- Christ-Roberts CY, Pratipanawatr T, Pratipanawatr W, Berria R, Belfort R, Kashyap S, Mandarino LJ (2004) Exercise training increases glycogen synthase activity and GLUT4 expression but not insulin signaling in overweight nondiabetic and type 2 diabetic subjects. Metab Clin Exp 53:1233–1242CrossRefGoogle Scholar
- Dutka TL, Mollica JP, Lamboley CR, Weerakkody VC, Greening DW, Posterino GS, Murphy RM, Lamb GD (2017) S-nitrosylation and S-glutathionylation of Cys134 on troponin I have opposing competitive actions on Ca2+ sensitivity in rat fast-twitch muscle fibers. Am J Physiol Cell Physiol 312:C316-c327CrossRefGoogle Scholar
- Froemming GR, Murray BE, Harmon S, Pette D, Ohlendieck K (2000) Comparative analysis of the isoform expression pattern of Ca(2+)-regulatory membrane proteins in fast-twitch, slow-twitch, cardiac, neonatal and chronic low-frequency stimulated muscle fibers. Biochim Biophys Acta 1466:151–168CrossRefGoogle Scholar
- Garvey SM, Russ DW, Skelding MB, Dugle JE, Edens NK (2015) Molecular and metabolomic effects of voluntary running wheel activity on skeletal muscle in late middle-aged rats. Physiol Rep 3:E12319Google Scholar
- Heinemeier KM, Olesen JL, Schjerling P, Haddad F, Langberg H, Baldwin KM, Kjaer M (2007) Short-term strength training and the expression of myostatin and IGF-I isoforms in rat muscle and tendon: differential effects of specific contraction types. J Appl Physiol 102:573–581CrossRefPubMedPubMedCentralGoogle Scholar
- Henriksen EJ, Halseth AE (1995) Adaptive responses of GLUT-4 and citrate synthase in fast-twitch muscle of voluntary running rats. Am J Physiol 268:R130-134Google Scholar
- Perry BD, Wyckelsma VL, Murphy RM, Steward CH, Anderson M, Levinger I, Petersen AC, McKenna MJ (2016) Dissociation between short-term unloading and resistance training effects on skeletal muscle Na+,K+-ATPase, muscle function, and fatigue in humans. J Appl Physiol (1985) 121:1074–1086CrossRefGoogle Scholar
- Steffen JM, Musacchia XJ (1984) Effect of hypokinesia and hypodynamia on protein, RNA, and DNA in rat hindlimb muscles. Am J Physiol 247:R728-732Google Scholar
- Watanabe D, Kanzaki K, Kuratani M, Matsunaga S, Yanaka N, Wada M (2015) Contribution of impaired myofibril and ryanodine receptor function to prolonged low-frequency force depression after in situ stimulation in rat skeletal muscle. J Muscle Res Cell Motil 36:275–286CrossRefPubMedPubMedCentralGoogle Scholar
- Wyckelsma VL, McKenna MJ, Serpiello FR, Lamboley CR, Aughey RJ, Stepto NK, Bishop DJ, Murphy RM (2015) Single-fiber expression and fiber-specific adaptability to short-term intense exercise training of Na+-K+-ATPase alpha- and beta-isoforms in human skeletal muscle. J Appl Physiol (1985) 118:699–706CrossRefGoogle Scholar