Hypertrophy of mature Xenopus muscle fibres in culture induced by synergy of albumin and insulin

Jaspers, Richard T.; Beek-Harmsen, Brechje J. van; Blankenstein, Marinus A.; Goldspink, Geoffrey; Huijing, P.A.J.B.M.; Laarse, Willem J. van der

doi:10.1007/s00424-008-0499-0

Cited by 13 publications

(12 citation statements)

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“…Quantitative fiber type differentiating approaches obtain insight into interactions between pathways and the integrated effects of different loading programs and stimuli. For example, ex vivo culture systems of mature muscle fibers (Jaspers 2004; Jaspers et al 2008) are well defined and can be used for controlled manipulation of growth factors, mechanical loading and oxygen tension, either independently or in combination. Such approaches may uncover interactions between signal transduction routes, which are to be verified in vivo.…”

Section: Discussionmentioning

confidence: 99%

“…In addition to mechanical loading-induced expression of local factors, several other components such as albumin, IGF-binding proteins, receptors, cytokines (i.e., TNF-1α, IL-1 and IL-6), calcium and vitamins may modulate the effects of IGF-I and myostatin (Casse et al 2003; Clemmons 1998; Coletti et al 2005; Jaspers et al 2008; Ling et al 1997; Pfeifer et al 2002). For example, insulin receptor phosphorylation, insulin receptor substrate (IRS-2) phosphorylation, as well as the downstream PI3K activity were all shown to be significantly higher in the high oxidative soleus compared to EDL (Song et al 1999).…”

Section: Pathways and Stimuli Regulating Protein Turnover In Differenmentioning

confidence: 99%

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The muscle fiber type–fiber size paradox: hypertrophy or oxidative metabolism?

et al. 2010

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An inverse relationship exists between striated muscle fiber size and its oxidative capacity. This relationship implies that muscle fibers, which are triggered to simultaneously increase their mass/strength (hypertrophy) and fatigue resistance (oxidative capacity), increase these properties (strength or fatigue resistance) to a lesser extent compared to fibers increasing either of these alone. Muscle fiber size and oxidative capacity are determined by the balance between myofibrillar protein synthesis, mitochondrial biosynthesis and degradation. New experimental data and an inventory of critical stimuli and state of activation of the signaling pathways involved in regulating contractile and metabolic protein turnover reveal: (1) higher capacity for protein synthesis in high compared to low oxidative fibers; (2) competition between signaling pathways for synthesis of myofibrillar proteins and proteins associated with oxidative metabolism; i.e., increased mitochondrial biogenesis via AMP-activated protein kinase attenuates the rate of protein synthesis; (3) relatively higher expression levels of E3-ligases and proteasome-mediated protein degradation in high oxidative fibers. These observations could explain the fiber type–fiber size paradox that despite the high capacity for protein synthesis in high oxidative fibers, these fibers remain relatively small. However, it remains challenging to understand the mechanisms by which contractile activity, mechanical loading, cellular energy status and cellular oxygen tension affect regulation of fiber size. Therefore, one needs to know the relative contribution of the signaling pathways to protein turnover in high and low oxidative fibers. The outcome and ideas presented are relevant to optimizing treatment and training in the fields of sports, cardiology, oncology, pulmonology and rehabilitation medicine.Electronic supplementary materialThe online version of this article (doi:10.1007/s00421-010-1545-0) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Section: Pathways and Stimuli Regulating Protein Turnover In Differenmentioning

confidence: 99%

The muscle fiber type–fiber size paradox: hypertrophy or oxidative metabolism?

et al. 2010

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“…In addition, differential changes in rat and human GM geometry during growth may be explained by growth factor signalling during development. Recently, studies using ex vivo culture of mature isolated muscle fibres, showed that muscle anabolic growth factors induce radial muscle fibre growth (trophy) without longitudinal growth (Jaspers et al. 2008; Watt et al.…”

Section: Discussionmentioning

confidence: 99%

Effects of growth on geometry of gastrocnemius muscle in children: a three-dimensional ultrasound analysis

et al. 2011

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During development, muscle growth is usually finely adapted to meet functional demands in daily activities. However, how muscle geometry changes in typically developing children and how these changes are related to functional and mechanical properties is largely unknown. In rodents, longitudinal growth of the pennate m. gastrocnemius medialis (GM) has been shown to occur mainly by an increase in physiological cross-sectional area and less by an increase in fibre length. Therefore, we aimed to: (i) determine how geometry of GM changes in healthy children between the ages of 5 and 12 years, (ii) test whether GM geometry in these children is affected by gender, (iii) compare normalized growth of GM geometry in children with that in rats at similar normalized ages, and (iv) investigate how GM geometry in children relates to range of motion of angular foot movement at a given moment. Thirty children (16 females, 14 males) participated in the study. Moment-angle data were collected over a range of angles by rotating the foot from plantar flexion to dorsal flexion at standardized moments. GM geometry in the mid-longitudinal plane was measured using threedimensional ultrasound imaging. This geometry was compared with that of GM geometry in rats. During growth from 5 to 12 years of age, the mean neutral footplate angle (0 Nm) occurred at )5°(SD 7°) and was not a function of age. Measured at standardized moments (4 Nm), footplate angles towards plantar flexion and dorsal flexion decreased by 25 and 40%, respectively. In both rats and children, GM muscle length increased proportionally with tibia length. In children, the length component of the physiological crosssectional area and fascicle length increased by 7 and 5% per year, respectively. Fascicle angle did not change over the age range measured. In children, the Achilles tendon length increased by 6% per year. GM geometry was not affected by gender. We conclude that, whereas the length of GM in rat develops mainly by an increase in physiological cross-sectional area of the muscle, GM in children develops by uniform scaling of the muscle. This effect is probably related to the smaller fascicle angle in human GM, which entails a smaller contribution of radial muscle growth to increased GM muscle length. The net effect of uniform scaling of GM muscle belly causes it to be stiffer, explaining the decrease in range of motion of angular foot movement at 4 Nm towards dorsal flexion during growth.

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“…During adolescence, serum levels of growth factors are increased (Clark & Rogol, 1996;Rogol et al 2002). For ex vivo cultured mature muscle fibres, such growth factors induce hypertrophy, and no addition of sarcomeres in series (Jaspers et al 2008;Watt et al 2010). Therefore, if elevated serum levels of growth factors are involved in muscle development, their effects are likely to appear as hypertrophy rather than as addition of sarcomeres in series.…”

Section: Introductionmentioning

confidence: 99%

Medial gastrocnemius muscle growth during adolescence is mediated by increased fascicle diameter rather than by longitudinal fascicle growth

et al. 2015

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Using a cross-sectional design, the purpose of this study was to determine how pennate gastrocnemius medialis (GM) muscle geometry changes as a function of adolescent age. Sixteen healthy adolescent males (aged 10-19 years) participated in this study. GM muscle geometry was measured within the mid-longitudinal plane obtained from a 3D voxel-array composed of transverse ultrasound images. Images were taken at footplate angles corresponding to standardised externally applied footplate moments (between 4 Nm plantar flexion and 6 Nm dorsal flexion). Muscle activity was recorded using surface electromyography (EMG), expressed as a percentage of maximal voluntary contraction (%MVC). To minimise the effects of muscle excitation, EMG inclusion criteria were set at < 10% of MVC. In practice, however, normalised EMG levels were much lower. For adolescent subjects with increasing ages, GM muscle (belly) length increased due to an increase in the length component of the physiological cross-sectional area measured within the mid-longitudinal plane. No difference was found between fascicles at different ages, but the aponeurosis length and pennation angle increased by 0.5 cm year À1 and 0.5°per year, respectively. Footplate angles corresponding to externally applied 0 and 4 Nm plantarflexion moments were not associated with different adolescent ages. In contrast, footplate angles corresponding to externally applied 4 and 6 Nm dorsal flexion moments decreased by 10°between 10 and 19 years. In conclusion, we found that in adolescents' pennate GM muscles, longitudinal muscle growth is mediated predominantly by increased muscle fascicle diameter.

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Hypertrophy of mature Xenopus muscle fibres in culture induced by synergy of albumin and insulin

Cited by 13 publications

References 60 publications

The muscle fiber type–fiber size paradox: hypertrophy or oxidative metabolism?

The muscle fiber type–fiber size paradox: hypertrophy or oxidative metabolism?

Effects of growth on geometry of gastrocnemius muscle in children: a three-dimensional ultrasound analysis

Medial gastrocnemius muscle growth during adolescence is mediated by increased fascicle diameter rather than by longitudinal fascicle growth

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