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

  • Plantaris Muscle weakness in old mice relative contributions of changes in specific force Muscle mass myofiber cross sectional area and number
    Age, 2014
    Co-Authors: Sam B Ballak, Hans Degens, Tinelies Busepot, Arnold De Haan, Richard T Jaspers
    Abstract:

    The age-related decline in Muscle function contributes to the movement limitations in daily life in old age. The age-related loss in Muscle force is attributable to loss of myofibers, myofiber atrophy, and a reduction in specific force. The contribution of each of these determinants to Muscle weakness in old age is, however, largely unknown. The objective of this study is to determine whether a loss in myofiber number, myofiber atrophy, and a reduction in specific Muscle force contribute to the age-related loss of Muscle force in 25-month-old mouse. Maximal isometric force of in situ m. Plantaris of C57BL/6J male adult (9 months) and old (25 months) mice was determined and related to myofiber number, myofiber size, intramuscular connective tissue content, and proportion of denervated myofibers. Isometric maximal Plantaris Muscle force was 13 % lower in old than adult mice (0.97 ± 0.05 N vs. 0.84 ± 0.03 N; P < 0.05). M. Plantaris mass of old mice was not significantly smaller than that of adult mice. There was also no significant myofiber atrophy or myofiber loss. Specific Muscle force of old mice was 25 % lower than that of adult mice (0.55 ± 0.05 vs. 0.41 ± 0.03 N·mm−2, P < 0.01). In addition, with age, the proportion of type IIB myofibers decreased (43.6 vs. 38.4 %, respectively), while the connective tissue content increased (11.6 vs. 16.4 %, respectively). The age-related reduction in maximal isometric Plantaris Muscle force in 25-month-old male C57BL/6J mice is mainly attributable to a reduction in specific force, which is for 5 % explicable by an age-related increase in connective tissue, rather than myofiber atrophy and myofiber loss.

  • the time course of myonuclear accretion during hypertrophy in young adult and older rat Plantaris Muscle
    Annals of Anatomy-anatomischer Anzeiger, 2011
    Co-Authors: Sander F T Van Der Meer, Hans Degens, Richard T Jaspers, David Jones
    Abstract:

    To investigate whether accretion of myonuclei precedes or follows the increase in fibre cross-sectional area and whether this time course is affected by age, left Plantaris Muscle of 5- and 25-month-old male Wistar rats was overloaded by denervation of its synergists for 1, 2 or 4 weeks. Contralateral Plantaris Muscle served as control. Myonuclei were counted in haematoxylin-stained cross-sections. While hypertrophy (33% in young adult) became significant after 2 weeks overload (p<0.01), the myonuclear number was increased only at 4 weeks of overload (p<0.001). The time course and magnitude of hypertrophy were similar in young adult and older rats. Older Muscles contained 26% more myonuclei per mm fibre length (p=0.001) and had a 10-fold larger proportion of central myonuclei (p<0.001) than young adult Muscles. In conclusion, our data indicate that Muscle fibre hypertrophy precedes the acquisition of new myonuclei and that the ability to develop hypertrophy is not attenuated or delayed in 25-month-old rat Muscle.

  • fiber capillary supply related to fiber size and oxidative capacity in human and rat skeletal Muscle
    Advances in Experimental Medicine and Biology, 2009
    Co-Authors: Rob C I Wust, Sarah L Gibbings, Hans Degens
    Abstract:

    The capillary supply of a Muscle fiber is thought to be determined by its type, oxidative capacity, size and metabolic surrounding. Size and oxidative capacity, however, differ between fiber types. To investigate which of these factors determines the capillary supply of a myofiber most we analysed in sections from human vastus lateralis (n = 11) and rat Plantaris Muscle (n = 8) the type, succinate dehydrogenase activity (SDH), reflecting oxidative capacity, and capillary supply of individual fibers. Capillary fiber density differed between fiber types in rat (P <0.03) but not in human Muscle. In human Muscle only, the local capillary to fiber ratio (LCFR) correlated with the integrated SDH (fiber cross-sectional area • SDH) of a fiber (R = 0.62; P < 0.001). Backward multiple regression revealed, however, that the LCFR was primarily determined by fiber size, type (R = 0.71, human) and surrounding of the fiber (R = 0.62; rat Plantaris Muscle), i.e. whether it came from the deep or superficial region of the Muscle (all P < 0.001) and not SDH. In conclusion, size, type and metabolic surrounding rather than mitochondrial activity determine the capillary supply to a Muscle fiber.

  • 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.

Roland R Roy - One of the best experts on this subject based on the ideXlab platform.

  • calcineurin and heat shock protein 72 in functionally overloaded rat Plantaris Muscle
    Biochemical and Biophysical Research Communications, 2005
    Co-Authors: Yasuharu Oishi, Tomonori Ogata, Yoshinobu Ohira, Kohachi Taniguchi, Roland R Roy
    Abstract:

    The involvement of calcineurin (CaN) and heat shock protein (Hsp) 72 in the regulation of fiber size and/or phenotype in response to functional overload (FO) was investigated. In one FO group, the Plantaris Muscle was overloaded by cutting the distal tendons (5–10 mm length) of the soleus and gastrocnemius of 3-week-old male Wistar rats. Cyclosporin A (CsA), a CaN inhibitor, was injected daily (5 mg/kg body weight, i.p.) in a second group of FO rats (FO + CsA group) for a 2-week period. Compared to age-matched controls (Con), the absolute and relative Plantaris weights were increased in both FO groups: the hypertrophic response was attenuated in FO + CsA rats. The mean cross-sectional area of each fiber type was increased (∼2.0-fold) in the Plantaris of FO rats: CsA treatment attenuated this effect, although the fibers were still larger than in Con rats. The percent composition of myosin heavy chain (MHC) IIb decreased from 54% in Con to 19% in FO rats, whereas types I, IIa, and IIx MHC increased in the FO rats. CsA treatment blunted the shifts in MHC isoforms: the FO + CsA group showed a smaller decrease in type IIb and a smaller increase in type IIx MHC than the FO group. The levels of CaN-A and -B proteins were higher (∼2.5-fold) in FO than Con rats, whereas these values were similar in Con and FO + CsA rats. Hsp72 protein levels were higher in FO (3.6-fold) and FO + CsA (5.2-fold) than Con rats, with the values being significantly higher in the FO + CsA than FO rats. CsA treatment in Con rats had no effects on Muscle mass, fiber size, MHC composition, and Hsp72 or CaN levels. Combined, these results suggest that CaN levels are related to changes in both fiber size and phenotype, and that Hsp72 levels are more related to the levels of stress added to the Muscle rather than to increases in the slow fiber phenotype in functionally overloaded rat Plantaris Muscles.

  • hypertrophy of rat Plantaris Muscle fibers after voluntary running with increasing loads
    Journal of Applied Physiology, 1998
    Co-Authors: Akihiko Ishihara, Yoshinobu Ohira, Roland R Roy, Yasuhiko Ibata, Reggie V Edgerton
    Abstract:

    There have been no systematic comparisons of skeletal Muscle adaptations in response to voluntary wheel running under controlled loading conditions. To accomplish this, a voluntary running wheel fo...

  • mhc and sarcoplasmic reticulum protein isoforms in functionally overloaded cat Plantaris Muscle fibers
    Journal of Applied Physiology, 1996
    Co-Authors: Robert J Talmadge, Roland R Roy, G R Chalmers, V R Edgerton
    Abstract:

    To determine whether the adaptations in myosin heavy chain (MHC) isoform expression after functional overload (FO) are accompanied by commensurate adaptations in protein isoforms responsible for relaxation [sarco(endo)plasmic reticulum (SR) Ca(2+)-adenosinetriphosphatase (SERCA) and phospholamban (PHL)] in single Muscle fibers, the isoforms of MHC and SERCA and the presence or absence of PHL were determined for cat Plantaris fibers 3 mo after FO. In control Plantaris the relative MHC isoform composition was 23% type I, 21% type IIa, and 56% type IIb. FO resulted in a shift toward slower isoforms (33% type I, 44% type IIa, and 23% type IIb). In the deep region of the Plantaris the proportions of type I MHC and hybrid MHC fibers (containing type I and II MHCs) were 40 and 200% greater in FO cats, respectively. FO resulted in a 47% increase in the proportion of fibers containing only the slow SERCA isoform (SERCA2) and a 41% increase in the proportion of fibers containing PHL. The proportions of fibers containing type I MHC, SERCA2, and PHL in control and FO Plantaris were linearly correlated. These data show that adaptations in MHC isoform expression are accompanied by commensurate adaptations in sarcoplasmic reticulum protein isoforms in single Muscle fibers after FO.

  • response of mouse Plantaris Muscle to functional overload comparison with rat and cat
    Comparative Biochemistry and Physiology Part A: Physiology, 1995
    Co-Authors: Roland R Roy, V R Edgerton
    Abstract:

    Abstract Functional overload (FO) of a Muscle by removing its synergists results in a compensatory hypertrophy of the Muscle. However, the extent of the response appears to be dependent, at least in part, on the activity and/or loading levels of the Muscle following surgery. Thus, differences in the inherent physical activity levels across species may be an important factor to consider. In the present study, the effects of 8 weeks of FO on the isometric mechanical properties of the Plantaris of mice (highly active) were determined and the findings compared with the results from previous studies performed on the Plantaris of rats (highly active) and cats (less active). FO resulted in approximately a doubling of the mass, the physiological cross-sectional area and the maximum tetanic tension capacity of the mouse Plantaris. Thus, the specific tension, i.e. the maximum tetanic tension per unit cross-sectional area, was similar in the Plantaris of control and FO mice. Isometric twitch speed properties were unaffected, but the tension enhancement in response to an increase in the rate of stimulation showed the pattern of a “faster” Muscle following FO. The fatigue resistance of the Plantaris in FO mice was significantly higher than in control mice. Although the degree of hypertrophy that occurred in the mouse Plantaris was similar to that observed after FO in rats and in cats that are exercised intermittently at high intensities, there were differences in the mechanical properties that may be related to the adaptability of species and/or the behavioral responses to the overload.

Phillip F. Gardiner - One of the best experts on this subject based on the ideXlab platform.

  • resting membrane potential of rat Plantaris Muscle fibers after prolonged indirect stimulation in situ effect of glucose infusion
    Canadian Journal of Applied Physiology-revue Canadienne De Physiologie Appliquee, 2005
    Co-Authors: Antony D. Karelis, François Péronnet, Phillip F. Gardiner
    Abstract:

    The purpose of this study was to determine whether glucose infusion during prolonged indirect Muscle stimulation (50 Hz for 200 ms every 2.7 s at 5 V) would have an effect on resting membrane potential (RMP). The RMP measured at Min 1 in the recovery period following stimulation of the rat Plantaris Muscle for 60 min in situ was significantly decreased in control rats, but was back to baseline values within 2 min. When glucose was infused ([glucose] approximately 10 mM), no change was observed in RMP, and Muscle fatigue and the reduction in M-wave peak-to-peak amplitude were both attenuated. However, Muscle force and the electrical properties of the membrane were deteriorated both in rats infused with glucose and in control rats at Min 2 during the recovery period, at a time when RMP was not modified. These observations suggest that the effect of increased circulating glucose on fatigue-associated reductions in Muscle fiber RMP seems to be modest and short-lived. Therefore, the attenuating effect of elevated glucose on Muscle fatigue responses could be through mechanisms other than those associated with maintenance of RMP during fatigue.

  • enhanced neuromuscular transmission efficacy in overloaded rat Plantaris Muscle
    Muscle & Nerve, 2004
    Co-Authors: Anteneh Argaw, Patrice Desaulniers, Phillip F. Gardiner
    Abstract:

    To better understand the effect of Muscle hypertrophy on the physiological properties of transmitter release, we investigated neuromuscular transmission (NMT) efficacy in overloaded rat Plantaris Muscle in situ. In the overload group, following bilateral tenotomy of Plantaris synergists, rats were confined to wheel-cages. Age-matched rats in the control group were confined to plastic cages. During the terminal experiment, Muscle action potentials were blocked using μ-conotoxin, and full-sized endplate potentials (EPPs) were recorded at 25, 50, and 75 HZ to determine their amplitude rundown. Quantal contents for the control and overload groups were 37.0 and 74.3, respectively (P <0.01). There was a significant group difference in EPP amplitude rundown at all frequencies examined, with increased rundown occurring in the overload group (P < 0.01). Cumulative quantal release was 139% and 153% higher in the overload group at 25 and 50 HZ, respectively (P < 0.05). Together, these data suggest the safety factor for NMT is increased by neuromuscular overload. Furthermore, these findings support and supplement previously reported activity-dependent improvements in NMT efficacy that are probably mediated via presynaptic adaptations. Muscle Nerve 29: 89–96, 2004

  • Insulin does not mediate the attenuation of fatigue associated with glucose infusion in rat Plantaris Muscle.
    Journal of applied physiology (Bethesda Md. : 1985), 2003
    Co-Authors: Antony D. Karelis, François Péronnet, Phillip F. Gardiner
    Abstract:

    Glucose infusion attenuates fatigue in rat Plantaris Muscle stimulated in situ, and this is associated with a better maintenance of electrical properties of the fiber membrane (Karelis AD, Peronnet...

  • glucose infusion attenuates Muscle fatigue in rat Plantaris Muscle during prolonged indirect stimulation in situ
    Experimental Physiology, 2002
    Co-Authors: Antony D. Karelis, François Péronnet, Phillip F. Gardiner
    Abstract:

    Carbohydrate ingestion increases both endurance time to exhaustion during prolonged exercise, and the ability to perform resistance exercise. The mechanism(s) underlying the increased performance following glucose ingestion remain(s) unclear. The purpose of the present study was to verify the hypothesis that glucose infusion could attenuate peripheral Muscle fatigue in the anaesthetized rat during prolonged indirect electrical stimulation in situ. For this purpose the Plantaris Muscle was electrically stimulated (50 Hz for 200 ms every 2.7 s; 5 V; pulse width, 0.05 ms) in situ through the sciatic nerve to perform concentric contractions for 60 min while infusing intravenously either saline alone (7.25 ml kg(-1) h(-1)), or saline and glucose (1 g kg(-1) h(-1): plasma glucose 11 +/- 1.1, vs. 4.9 +/- 0.2 mm with infusion of saline) (8 rats per group). Glucose infusion attenuated the reduction in submaximal peak dynamic force (55% decrease vs. 70% decrease in rats infused with saline alone, P < 0.05). In a third group of rats (n = 8), infusion of glucose 30 min after the start of stimulation partially restored submaximal peak dynamic force (P < 0.05). Maximum dynamic and isometric forces at the end of the period of stimulation were also higher (P < 0.05) in rats infused with glucose (4.0 +/- 0.2 and 4.3 +/- 0.2 N, respectively) than saline alone (3.0 +/- 0.2 and 3.5 +/- 0.2 N, respectively). The beneficial effect of glucose infusion on peripheral Muscle force during prolonged stimulation was not associated with a reduction in Muscle glycogen utilisation, nor with a reduction of fatigue at the neuromuscular junction, as assessed through maximal direct Muscle stimulation (200 Hz for 200 ms; 150 V; pulse width, 0.05 ms). However, changes in M-wave peak-to-peak amplitude, duration and total area suggest that glucose infusion, and/or the associated increase in plasma insulin concentration, may prevent the deterioration of electrical properties of the Muscle fibre membrane.

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.

  • specific force of the rat Plantaris Muscle changes with age but not with overload
    Mechanisms of Ageing and Development, 1995
    Co-Authors: Hans Degens, L J Hoofd, Rob A. Binkhorst
    Abstract:

    Age and overload effects on the specific force of the rat Plantaris Muscle were investigated. The specific force was affected by age, but not by overload, inducing a 30% hypertrophy, at any age. The relative amount of non-contractile tissue only minimally affected the conclusions.

  • 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, L J 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.

V R Edgerton - One of the best experts on this subject based on the ideXlab platform.

  • mhc and sarcoplasmic reticulum protein isoforms in functionally overloaded cat Plantaris Muscle fibers
    Journal of Applied Physiology, 1996
    Co-Authors: Robert J Talmadge, Roland R Roy, G R Chalmers, V R Edgerton
    Abstract:

    To determine whether the adaptations in myosin heavy chain (MHC) isoform expression after functional overload (FO) are accompanied by commensurate adaptations in protein isoforms responsible for relaxation [sarco(endo)plasmic reticulum (SR) Ca(2+)-adenosinetriphosphatase (SERCA) and phospholamban (PHL)] in single Muscle fibers, the isoforms of MHC and SERCA and the presence or absence of PHL were determined for cat Plantaris fibers 3 mo after FO. In control Plantaris the relative MHC isoform composition was 23% type I, 21% type IIa, and 56% type IIb. FO resulted in a shift toward slower isoforms (33% type I, 44% type IIa, and 23% type IIb). In the deep region of the Plantaris the proportions of type I MHC and hybrid MHC fibers (containing type I and II MHCs) were 40 and 200% greater in FO cats, respectively. FO resulted in a 47% increase in the proportion of fibers containing only the slow SERCA isoform (SERCA2) and a 41% increase in the proportion of fibers containing PHL. The proportions of fibers containing type I MHC, SERCA2, and PHL in control and FO Plantaris were linearly correlated. These data show that adaptations in MHC isoform expression are accompanied by commensurate adaptations in sarcoplasmic reticulum protein isoforms in single Muscle fibers after FO.

  • response of mouse Plantaris Muscle to functional overload comparison with rat and cat
    Comparative Biochemistry and Physiology Part A: Physiology, 1995
    Co-Authors: Roland R Roy, V R Edgerton
    Abstract:

    Abstract Functional overload (FO) of a Muscle by removing its synergists results in a compensatory hypertrophy of the Muscle. However, the extent of the response appears to be dependent, at least in part, on the activity and/or loading levels of the Muscle following surgery. Thus, differences in the inherent physical activity levels across species may be an important factor to consider. In the present study, the effects of 8 weeks of FO on the isometric mechanical properties of the Plantaris of mice (highly active) were determined and the findings compared with the results from previous studies performed on the Plantaris of rats (highly active) and cats (less active). FO resulted in approximately a doubling of the mass, the physiological cross-sectional area and the maximum tetanic tension capacity of the mouse Plantaris. Thus, the specific tension, i.e. the maximum tetanic tension per unit cross-sectional area, was similar in the Plantaris of control and FO mice. Isometric twitch speed properties were unaffected, but the tension enhancement in response to an increase in the rate of stimulation showed the pattern of a “faster” Muscle following FO. The fatigue resistance of the Plantaris in FO mice was significantly higher than in control mice. Although the degree of hypertrophy that occurred in the mouse Plantaris was similar to that observed after FO in rats and in cats that are exercised intermittently at high intensities, there were differences in the mechanical properties that may be related to the adaptability of species and/or the behavioral responses to the overload.