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David J Parry - One of the best experts on this subject based on the ideXlab platform.

  • satellite cell activity is required for Hypertrophy of overloaded adult rat muscle
    Muscle & Nerve, 1994
    Co-Authors: David J Rosenblatt, David Yong, David J Parry
    Abstract:

    Hypertrophy of extensor digitorum longus muscle, overloaded by the removal of the synergist tibialis anterior (TA) muscle, in growing rats is inhibited if endogenous satellite cells are sterilized by exposure to irradiation. However, normal muscle growth is not eliminated, only diminished. To test whether irradiated, overloaded muscle can Hypertrophy in the absence of normal growth-related stimuli, experiments were conducted on mature rats. TA muscle ablation caused Hypertrophy of EDL muscle, characterized by a significant increase in muscle mass and the size of type IIx and type IIb fibers, and a proportional increase the number of myonuclei. When ablation was preceded by irradiation Hypertrophy did not occur. The results indicate that satellite cell activation, division, and fusion is necessary for Compensatory Hypertrophy of fully mature muscle, and may be important to the understanding of the limits of recovery of inherited muscle myopathies treated by myogenic cell implantation. © 1994 John Wiley & Sons, Inc.

  • satellite cell activity is required for Hypertrophy of overloaded adult rat muscle
    Muscle & Nerve, 1994
    Co-Authors: David J Rosenblatt, David Yong, David J Parry
    Abstract:

    Hypertrophy of extensor digitorum longus muscle, overloaded by the removal of the synergist tibialis anterior (TA) muscle, in growing rats is inhibited if endogenous satellite cells are sterilized by exposure to irradiation. However, normal muscle growth is not eliminated, only diminished. To test whether irradiated, overloaded muscle can Hypertrophy in the absence of normal growth-related stimuli, experiments were conducted on mature rats. TA muscle ablation caused Hypertrophy of EDL muscle, characterized by a significant increase in muscle mass and the size of type IIx and type IIb fibers, and a proportional increase the number of myonuclei. When ablation was preceded by irradiation Hypertrophy did not occur. The results indicate that satellite cell activation, division, and fusion is necessary for Compensatory Hypertrophy of fully mature muscle, and may be important to the understanding of the limits of recovery of inherited muscle myopathies treated by myogenic cell implantation. © 1994 John Wiley & Sons, Inc.

  • gamma irradiation prevents Compensatory Hypertrophy of overloaded mouse extensor digitorum longus muscle
    Journal of Applied Physiology, 1992
    Co-Authors: J D Rosenblatt, David J Parry
    Abstract:

    Mouse extensor digitorum longus (EDL) muscle was subjected to a dose of gamma irradiation that causes reproductive death of satellite cells and/or to chronic Compensatory overload, achieved by removal of the distal portion of the tibialis anterior muscle. Four weeks later the mass, fiber type percentage, and fiber size of the EDL muscle were measured. Both the irradiated + overloaded and the irradiated only EDL muscles were significantly lighter and contained significantly smaller fibers than untreated muscle or muscle subjected to chronic overload only. Overload muscle, whether irradiated or not, had a larger percentage of type IIx fibers and a smaller percentage of type IIb fibers than muscle that had not been overloaded. The results confirm that satellite cell proliferation is a prerequisite for muscle Hypertrophy induced by synergist incapacitation, but it appears not to be required for the maintenance of, or change in, normal muscle fiber myosin heavy chain phenotype expression.

Hans Degens - One of the best experts on this subject based on the ideXlab platform.

  • Vascular endothelial growth factor, capillarization, and function of the rat plantaris muscle at the onset of Hypertrophy.
    Japanese Journal of Physiology, 2003
    Co-Authors: Hans Degens, Jo Ann Moore, Stephen E. Alway
    Abstract:

    Capillary proliferation occurs during Compensatory Hypertrophy. We investigated whether the expression of vascular endothelial growth factor (VEGF) is elevated at the onset of Hypertrophy when capillary proliferation is minimal, and whether muscle damage as assessed by muscle force deficits, may occur at the onset of Hypertrophy. To investigate this, we induced in 9-month-old rats, under isoflurane anesthesia, Hypertrophy of the left plantaris muscle by denervation of the gastrocnemius and soleus muscles. Capillarization was investigated in both the deep (oxidative) and the superficial (glycolytic) regions of the plantaris muscle. After 2 weeks, muscle mass had increased by 16% (p< 0.01), which was not accompanied by increases in fiber size. The maximal tetanic force (P(0)) and specific tension (P(0).g(-1) or P(0).cm(2)) and twitch characteristics were unaltered, and fatigue resistance of the overloaded muscle was improved (p< 0.05). However, the myosin heavy chain composition was unaltered. Capillary proliferation was not yet evident, but VEGF mRNA and protein levels were elevated 1.5- and 8-fold, respectively (p< 0.05). We concluded that the normal specific tension and the elevated VEGF expression after 2 weeks of overload indicate (1) an absence of or minimal muscle damage at this early time point, and (2) that elevated VEGF expression precedes and is involved in capillary proliferation that occurs during the later stages of Compensatory Hypertrophy.

  • the development of Compensatory Hypertrophy in the plantaris muscle of the rat
    Annals of Anatomy-anatomischer Anzeiger, 1995
    Co-Authors: Hans Degens, N E L Meessen, P Wirtz, Rob A. Binkhorst
    Abstract:

    The aim of this investigation was to study the time course of Compensatory Hypertrophy (CH) over a seven week period after its surgical induction in the lower limb of the rat. CH of the left plantaris muscle of the rat was induced by denervation of the ipsilateral gastrocnemius and soleus muscles. Muscle fibres were classified as type I, Ic, IIa and IIb. Hypertrophy of the muscle was first observed about ten days after induction of CH. All fibre types appeared to contribute to this Hypertrophy. During the period between four and twenty eight days there was a marked increase in the percentage of type I fibres, mainly at the expense of type IIa, as compared with control muscles. During this CH period so called 'intermediate' Ic fibres were found, indicating fibre type transition taking place. The isometric twitch time to peak tension (TPT) of the plantaris muscle was studied in situ. The TPT of CH muscles remained the same during the experimental period of seven weeks. This might be explained by the effect of the increase in type I (slow) fibres being masked by the far larger number of fast fibres, which still accounted for approximately 79% of the total number of fibres after CH.

  • capillary proliferation related to fibre types in hypertrophied aging rat m plantaris
    Advances in Experimental Medicine and Biology, 1994
    Co-Authors: Hans Degens, Zdenek Turek, Louis Hoofd, Rob A. Binkhorst
    Abstract:

    Most studies on ageing describe an age-related muscle fibre atrophy and an increase in the percentage of type I (oxidative) and IIa (oxidative glycolytic) fibres and a decrease in the percentage of IIb (glycolytic) fibres (Kovanen, 1989). Compensatory Hypertrophy is characterised by enlargement of existing fibres and an increased percentage of type I fibres (Riedy et al., 1985). Since muscle fibre type and size are correlated with the capillary supply to a fibre (Egginton and Ross, 1989), changes in muscle capillary supply might accompany changes in fibre type composition and fibre cross-sectional areas. Absence of capillary proliferation with Hypertrophy would result in increased diffusion distances from the capillary to the interior of fibres, which might impede the delivery of oxygen to the interior of fibres. However, little is known about capillarisation in ageing rat muscles not to mention capillarisation in hypertrophied ageing muscle. Therefore, in the present study we investigated the capillarisation in muscles at various ages and, in particular, we wanted to elucidate whether Compensatory Hypertrophy in ageing muscle was accompanied by capillary proliferation. This was done by the extended method of Capillary Domains as developed by Hoofd et al. (1985; Egginton and Ross, 1989).

  • The relationship between capillarisation and fibre types during Compensatory Hypertrophy of the plantaris muscle in the rat.
    Journal of anatomy, 1992
    Co-Authors: Hans Degens, Zdenek Turek, Louis Hoofd, Rob A. Binkhorst
    Abstract:

    Compensatory Hypertrophy of the plantaris muscle was obtained by denervation of its synergists. This Hypertrophy is characterised by a 32% increase in muscle mass. The muscle consists of type I and IIa (oxidative), and IIb (glycolytic) fibres. Fibres of all types were enlarged in hypertrophied muscles and the proportion of type I fibres was increased. We investigated the capillarisation after Hypertrophy as related to fibre type. In order to obtain this information a new technique was used, capable of estimating not only the traditional overall capillary density (CD) but also an index of heterogeneity in capillary spacing (LogSD), the 'local capillary to fibre ratio' (LCFR), obtained separately for each muscle fibre type, and finally a capillary density for each respective fibre type, the 'capillary fibre density' (CFD). It was found in both control and hypertrophied muscles that CD was higher in the deep (few IIb fibres) than in the superficial part of the muscle (considerable number of IIb fibres). The LogSD was lower, indicating less heterogeneity, in the deep than in the superficial part of the muscle. The LCFR and CFD of each fibre type was greater in the deep than in the superficial region of both control and hypertrophied muscles. Furthermore the CFD and LCFR were larger in type I and IIa fibres than in IIb fibres in each region of control and hypertrophied muscles. In hypertrophied muscles the CD was not significantly different from that of control muscles. However, LCFR of all fibre types was increased significantly in hypertrophied muscles as compared with controls, demonstrating capillary proliferation. The decreased CFD of type I and IIa fibres in the deep region of hypertrophied muscles as compared with controls suggests that here the capillary proliferation lags behind the increase in muscle mass. Endurance training had no significant effects for any region in any of the indices that were used.

David J Rosenblatt - One of the best experts on this subject based on the ideXlab platform.

  • satellite cell activity is required for Hypertrophy of overloaded adult rat muscle
    Muscle & Nerve, 1994
    Co-Authors: David J Rosenblatt, David Yong, David J Parry
    Abstract:

    Hypertrophy of extensor digitorum longus muscle, overloaded by the removal of the synergist tibialis anterior (TA) muscle, in growing rats is inhibited if endogenous satellite cells are sterilized by exposure to irradiation. However, normal muscle growth is not eliminated, only diminished. To test whether irradiated, overloaded muscle can Hypertrophy in the absence of normal growth-related stimuli, experiments were conducted on mature rats. TA muscle ablation caused Hypertrophy of EDL muscle, characterized by a significant increase in muscle mass and the size of type IIx and type IIb fibers, and a proportional increase the number of myonuclei. When ablation was preceded by irradiation Hypertrophy did not occur. The results indicate that satellite cell activation, division, and fusion is necessary for Compensatory Hypertrophy of fully mature muscle, and may be important to the understanding of the limits of recovery of inherited muscle myopathies treated by myogenic cell implantation. © 1994 John Wiley & Sons, Inc.

  • satellite cell activity is required for Hypertrophy of overloaded adult rat muscle
    Muscle & Nerve, 1994
    Co-Authors: David J Rosenblatt, David Yong, David J Parry
    Abstract:

    Hypertrophy of extensor digitorum longus muscle, overloaded by the removal of the synergist tibialis anterior (TA) muscle, in growing rats is inhibited if endogenous satellite cells are sterilized by exposure to irradiation. However, normal muscle growth is not eliminated, only diminished. To test whether irradiated, overloaded muscle can Hypertrophy in the absence of normal growth-related stimuli, experiments were conducted on mature rats. TA muscle ablation caused Hypertrophy of EDL muscle, characterized by a significant increase in muscle mass and the size of type IIx and type IIb fibers, and a proportional increase the number of myonuclei. When ablation was preceded by irradiation Hypertrophy did not occur. The results indicate that satellite cell activation, division, and fusion is necessary for Compensatory Hypertrophy of fully mature muscle, and may be important to the understanding of the limits of recovery of inherited muscle myopathies treated by myogenic cell implantation. © 1994 John Wiley & Sons, Inc.

Stephen E. Alway - One of the best experts on this subject based on the ideXlab platform.

  • Vascular endothelial growth factor, capillarization, and function of the rat plantaris muscle at the onset of Hypertrophy.
    Japanese Journal of Physiology, 2003
    Co-Authors: Hans Degens, Jo Ann Moore, Stephen E. Alway
    Abstract:

    Capillary proliferation occurs during Compensatory Hypertrophy. We investigated whether the expression of vascular endothelial growth factor (VEGF) is elevated at the onset of Hypertrophy when capillary proliferation is minimal, and whether muscle damage as assessed by muscle force deficits, may occur at the onset of Hypertrophy. To investigate this, we induced in 9-month-old rats, under isoflurane anesthesia, Hypertrophy of the left plantaris muscle by denervation of the gastrocnemius and soleus muscles. Capillarization was investigated in both the deep (oxidative) and the superficial (glycolytic) regions of the plantaris muscle. After 2 weeks, muscle mass had increased by 16% (p< 0.01), which was not accompanied by increases in fiber size. The maximal tetanic force (P(0)) and specific tension (P(0).g(-1) or P(0).cm(2)) and twitch characteristics were unaltered, and fatigue resistance of the overloaded muscle was improved (p< 0.05). However, the myosin heavy chain composition was unaltered. Capillary proliferation was not yet evident, but VEGF mRNA and protein levels were elevated 1.5- and 8-fold, respectively (p< 0.05). We concluded that the normal specific tension and the elevated VEGF expression after 2 weeks of overload indicate (1) an absence of or minimal muscle damage at this early time point, and (2) that elevated VEGF expression precedes and is involved in capillary proliferation that occurs during the later stages of Compensatory Hypertrophy.

Rob A. Binkhorst - One of the best experts on this subject based on the ideXlab platform.

  • the development of Compensatory Hypertrophy in the plantaris muscle of the rat
    Annals of Anatomy-anatomischer Anzeiger, 1995
    Co-Authors: Hans Degens, N E L Meessen, P Wirtz, Rob A. Binkhorst
    Abstract:

    The aim of this investigation was to study the time course of Compensatory Hypertrophy (CH) over a seven week period after its surgical induction in the lower limb of the rat. CH of the left plantaris muscle of the rat was induced by denervation of the ipsilateral gastrocnemius and soleus muscles. Muscle fibres were classified as type I, Ic, IIa and IIb. Hypertrophy of the muscle was first observed about ten days after induction of CH. All fibre types appeared to contribute to this Hypertrophy. During the period between four and twenty eight days there was a marked increase in the percentage of type I fibres, mainly at the expense of type IIa, as compared with control muscles. During this CH period so called 'intermediate' Ic fibres were found, indicating fibre type transition taking place. The isometric twitch time to peak tension (TPT) of the plantaris muscle was studied in situ. The TPT of CH muscles remained the same during the experimental period of seven weeks. This might be explained by the effect of the increase in type I (slow) fibres being masked by the far larger number of fast fibres, which still accounted for approximately 79% of the total number of fibres after CH.

  • capillary proliferation related to fibre types in hypertrophied aging rat m plantaris
    Advances in Experimental Medicine and Biology, 1994
    Co-Authors: Hans Degens, Zdenek Turek, Louis Hoofd, Rob A. Binkhorst
    Abstract:

    Most studies on ageing describe an age-related muscle fibre atrophy and an increase in the percentage of type I (oxidative) and IIa (oxidative glycolytic) fibres and a decrease in the percentage of IIb (glycolytic) fibres (Kovanen, 1989). Compensatory Hypertrophy is characterised by enlargement of existing fibres and an increased percentage of type I fibres (Riedy et al., 1985). Since muscle fibre type and size are correlated with the capillary supply to a fibre (Egginton and Ross, 1989), changes in muscle capillary supply might accompany changes in fibre type composition and fibre cross-sectional areas. Absence of capillary proliferation with Hypertrophy would result in increased diffusion distances from the capillary to the interior of fibres, which might impede the delivery of oxygen to the interior of fibres. However, little is known about capillarisation in ageing rat muscles not to mention capillarisation in hypertrophied ageing muscle. Therefore, in the present study we investigated the capillarisation in muscles at various ages and, in particular, we wanted to elucidate whether Compensatory Hypertrophy in ageing muscle was accompanied by capillary proliferation. This was done by the extended method of Capillary Domains as developed by Hoofd et al. (1985; Egginton and Ross, 1989).

  • The relationship between capillarisation and fibre types during Compensatory Hypertrophy of the plantaris muscle in the rat.
    Journal of anatomy, 1992
    Co-Authors: Hans Degens, Zdenek Turek, Louis Hoofd, Rob A. Binkhorst
    Abstract:

    Compensatory Hypertrophy of the plantaris muscle was obtained by denervation of its synergists. This Hypertrophy is characterised by a 32% increase in muscle mass. The muscle consists of type I and IIa (oxidative), and IIb (glycolytic) fibres. Fibres of all types were enlarged in hypertrophied muscles and the proportion of type I fibres was increased. We investigated the capillarisation after Hypertrophy as related to fibre type. In order to obtain this information a new technique was used, capable of estimating not only the traditional overall capillary density (CD) but also an index of heterogeneity in capillary spacing (LogSD), the 'local capillary to fibre ratio' (LCFR), obtained separately for each muscle fibre type, and finally a capillary density for each respective fibre type, the 'capillary fibre density' (CFD). It was found in both control and hypertrophied muscles that CD was higher in the deep (few IIb fibres) than in the superficial part of the muscle (considerable number of IIb fibres). The LogSD was lower, indicating less heterogeneity, in the deep than in the superficial part of the muscle. The LCFR and CFD of each fibre type was greater in the deep than in the superficial region of both control and hypertrophied muscles. Furthermore the CFD and LCFR were larger in type I and IIa fibres than in IIb fibres in each region of control and hypertrophied muscles. In hypertrophied muscles the CD was not significantly different from that of control muscles. However, LCFR of all fibre types was increased significantly in hypertrophied muscles as compared with controls, demonstrating capillary proliferation. The decreased CFD of type I and IIa fibres in the deep region of hypertrophied muscles as compared with controls suggests that here the capillary proliferation lags behind the increase in muscle mass. Endurance training had no significant effects for any region in any of the indices that were used.