Effects of eccentric and concentric training on capillarization and myosin heavy chain contents in rat skeletal muscles after hindlimb suspension

Department of Biomechanics, Medicine and Rehabilitation of the Locomotor Apparatus, Ribeirão Preto School of Medicine, University of São Paulo, Av. Bandeirantes 3900, Ribeirão Preto, SP, Brazil.
Acta histochemica (Impact Factor: 1.71). 02/2010; 113(3):277-82. DOI: 10.1016/j.acthis.2009.10.009
Source: PubMed

ABSTRACT We studied the effects of different protocols of post-disuse rehabilitation on angiogenesis and myosin heavy chain (MHC) content in rat hindlimb muscles after caudal suspension. Thirty female Wistar rats were divided into five groups: (1) Control I, (2) Control II, (3) Suspended, (4) Suspended trained on declined treadmill, and (5) Suspended trained on flat treadmill. Fragments of the soleus and tibialis anterior (TA) muscles were frozen and processed by electrophoresis and immunohistochemistry (CD31 antibody). Hindlimb suspension caused reduction of capillary/fiber (C/F) ratios and contents of MHC type I (MHCI) in the soleus in parallel to increased capillary density. Flat treadmill protocols increased the content of the MHCI isoform. The C/F ratio was increased by concentric training after hypokinesis, but was not modified by eccentric training, which caused a greater reduction of capillary density compared to the other protocols. In the TA muscle, hindlimb suspension caused a non-significant increase in capillary density and C/F ratio with limited changes in MHC. The present data demonstrate that the different training protocols adopted and the functional performance of the muscles analyzed caused specific changes in capillarization and in the content of the various MHC types.

Download full-text


Available from: Anabelle Silva Cornachione, Sep 26, 2015
19 Reads
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Sustained muscle wasting due to immobilization leads to weakening and severe metabolic consequences. The mechanisms responsible for muscle recovery after immobilization are poorly defined. Muscle atrophy induced by immobilization worsened in the lengthened tibialis anterior (TA) muscle, but not in the shortened gastrocnemius muscle. Here we investigated some mechanisms responsible for this differential response. Adult rats were subjected to unilateral hindlimb casting for 8 days (I8). Casts were removed at I8 and animals were allowed to recover for 10 days (R1 to R10). The worsening of TA atrophy following immobilization occurred immediately after cast removal at R1 and was sustained until R10. This atrophy correlated with a decrease in type IIb myosin heavy chain isoform and an increase in type IIx, IIa and I isoforms, with muscle connective tissue thickening, and with increased collagen (Col) I mRNA levels. Increased Col-XII, -IV, and -XVIII mRNA levels during TA immobilization normalized at R6. Sustained enhanced peptidase activities of the proteasome and apoptosome activity contributed to the catabolic response during the studied recovery period. Finally, increased nuclear apoptosis only prevailed in the connective tissue compartment of the TA. Altogether, the worsening of the TA atrophy pending immediate reloading reflects a major remodeling of its fiber type properties and alterations in the structure/composition of the extracellular compartment that may influence its elasticity/stiffness. The data suggest that sustained enhanced ubiquitin-proteasome-dependent proteolysis and apoptosis are important for these adaptations and provide some rationale for explaining the atrophy of reloaded muscles pending immobilization in a lengthened position.
    AJP Endocrinology and Metabolism 10/2012; 303(11). DOI:10.1152/ajpendo.00379.2012 · 3.79 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Remobilization of a previously immobilized rat right hindlimb in the ankle plantar-flexion-shortened position by free movement alone or associated with intermittent passive stretching was assessed by analysis of gait variables and dorsiflexion range of motion. The variables were related with the expression of extracellular matrix proteins and the addition of serial sarcomeres. Sixty-four female Wistar rats were divided into 8 groups: immobilized, free for 10 days, immobilized/stretched/free for 1, 3 or 10 days, immobilized/free for 1, 3 or 10 days. Gait variables, range of motion, serial sarcomeres number, localization and staining intensity of fibronectin, and expressions of types I and III collagen were analyzed. The hypokinesia changed the functional variables of gait, reduced the dorsiflexion range of motion (ROM), increased the number of fibers with intracellular fibronectin/total number of fibers (FIF/TNF), and decreased the expression of the type I collagen. After three days, morphological changes were exacerbated and the number of serial sarcomeres was increased in both groups, immobilized/stretched/free and immobilized/free. Functional impairment, ROM restriction and increased FIF/TNF were also observed. Despite the above described alterations, 10 days of stretching program increased the effectiveness of remobilization leading to recovery of the abnormalities observed in the muscle.
    Acta histochemica 12/2012; 115(5). DOI:10.1016/j.acthis.2012.11.001 · 1.71 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Stretching is frequently used in physiotherapy to minimize or even reverse the alterations that occur after muscle disuse. Alterations that occur after 10 and 21 days of maintained stretch in soleus and plantaris muscles post-disuse were evaluated in the present study in experimental rats. Thirty adult female Wistar rats were divided into seven groups: hindlimb immobilization for 10 days; immobilization and 10 days stretched; immobilized and 21 days stretched; three control groups consisting of animals of different ages and anesthetized group. The right hindlimb was immobilized using a lightweight apparatus composed of two sections: (i) upper part: a small cotton T-shirt and, and (ii) lower part: a steel mesh to fix the ankle in plantar-flexion-shortened position. Fragments of the soleus and plantaris muscle were frozen and processed using histochemical and immunohistochemical methods. Limb immobilization caused important morphological alterations in skeletal muscle including: reduction in the number of type I fibers and an increase in type IIC fibers, reduction in the lesser diameter of type I, IIA and IIAD fibers and in the number of capillaries in soleus muscle. The stretching program applied for 10 days was insufficient to allow recovery from the disuse alterations in both muscles. However, after 21 days there were improved morphological characteristics, size and distribution of the different fibers.
    Acta histochemica 12/2012; 115(5). DOI:10.1016/j.acthis.2012.11.008 · 1.71 Impact Factor
Show more