title: Aerobic exercise training improves Ca2+ handling and redox status of skeletal muscle in mice.
abstract: Exercise training is known to promote relevant changes in the properties of skeletal muscle contractility toward powerful fibers. However, there are few studies showing the effect of a well-established exercise training protocol on Ca(2+) handling and redox status in skeletal muscles with different fiber-type compositions. We have previously standardized a valid and reliable protocol to improve endurance exercise capacity in mice based on maximal lactate steady-state workload (MLSSw). The aim of this study was to investigate the effect of exercise training, performed at MLSSw, on the skeletal muscle Ca(2+) handling-related protein levels and cellular redox status in soleus and plantaris. Male C57BL/6J mice performed treadmill training at MLSSw over a period of eight weeks. Muscle fiber-typing was determined by myosin ATPase histochemistry, citrate synthase activity by spectrophotometric assay, Ca(2+) handling-related protein levels by Western blot and reduced to oxidized glutathione ratio (GSH:GSSG) by high-performance liquid chromatography. Trained mice displayed higher running performance and citrate synthase activity compared with untrained mice. Improved running performance in trained mice was paralleled by fast-to-slow fiber-type shift and increased capillary density in both plantaris and soleus. Exercise training increased dihydropyridine receptor (DHPR) alpha2 subunit, ryanodine receptor and Na(+)/Ca(2+) exchanger levels in plantaris and soleus. Moreover, exercise training elevated DHPR beta1 subunit and sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) 1 levels in plantaris and SERCA2 levels in soleus of trained mice. Skeletal muscle GSH content and GSH:GSSG ratio was increased in plantaris and soleus of trained mice. Taken together, our findings indicate that MLSSw exercise-induced better running performance is, in part, due to increased levels of proteins involved in skeletal muscle Ca(2+) handling, whereas this response is partially dependent on specificity of skeletal muscle fiber-type composition. Finally, we demonstrated an augmented cellular redox status and GSH antioxidant capacity in trained mice.
authors.affiliation: School of Physical Education and Sport, University of Sao Paulo (USP), São Paulo 05508-900, Brazil.
authors.forename: Julio C B
authors.initials: JC
authors.lastname: Ferreira
authors.forename: Aline V
authors.initials: AV
authors.lastname: Bacurau
authors.forename: Carlos R
authors.initials: CR
authors.lastname: Bueno
authors.forename: Telma C
authors.initials: TC
authors.lastname: Cunha
authors.forename: Leonardo Y
authors.initials: LY
authors.lastname: Tanaka
authors.forename: Maira A
authors.initials: MA
authors.lastname: Jardim
authors.forename: Paulo R
authors.initials: PR
authors.lastname: Ramires
authors.forename: Patricia C
authors.initials: PC
authors.lastname: Brum
mesh_terms: D015502:Absorptiometry, Photon; D000818:Animals; D001823:Body Composition; D002118:Calcium / Q000378:metabolism*; D008054:Lipid Peroxides / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000502:physiology*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011897:Random Allocation; D012420:Running / Q000502:physiology*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism
chemical_list: D008054:Lipid Peroxides; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002118:Calcium