The time course of denervation-induced changes is similar in soleus muscles of adult and old rats

Degens, Hans; Koşar, Şükran Nazan; Hopman, Maria T. E.; Haan, A. de

doi:10.1139/h07-189

Cited by 25 publications

(44 citation statements)

References 33 publications

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“…These observations are also robust to variations in the adjustable parameters of the transport model (Al-Shammari et al, 2012). Therefore, in the absence of extremes that are only associated with pathologies, our modelling predicts that VP provide a computationally simple and accurate approximation of functional capillary supply for muscle tissue cross sections of heterogeneous fibre types, which in turn theoretically validates the conclusions of modelling studies taking Voronoi polygons as a basis for morphometric analyses of maximal capillary supply in skeletal muscle tissues (Degens et al, 1992(Degens et al, , 2002(Degens et al, , 2006(Degens et al, , 2008Egginton et al, 2001;Wüst et al, 2009a;Ahmed et al, 1997).…”

Section: Discussionsupporting

confidence: 76%

“…In contrast, Voronoi polygons (Fig. 1B) generate a space-filling alternative (Egginton & Ross, 1989 thereby allowing the exploration of the local influences associated with microvascular remodelling, as well as any mismatch between angiogenesis and local O 2 demand (Degens et al, 1992(Degens et al, , 2002(Degens et al, , 2006(Degens et al, , 2008Egginton et al, 2001;Wüst et al, 2009a). This gives Voronoi polygons an advantage in assessing the efficacy of applications to pathological scenarios, such as ischaemia, where potential therapeutic interventions include strength training (Deveci & Egginton, 2002;Suzuki et al, 2000), endurance exercise (Ahmed et al, 1997;Scott et al, 2009), electrical stimulation (Ebina et al, 2002), and alterations in muscle temperature (Egginton et al, 2001;Egginton, 2002).…”

Section: Introductionmentioning

confidence: 99%

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Modelling capillary oxygen supply capacity in mixed muscles: Capillary domains revisited

Alshammari

Gaffney

Egginton

2014

Journal of Theoretical Biology

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Developing effective therapeutic interventions for pathological conditions associated with abnormal oxygen transport to muscle fibres critically depends on the objective characterisation of capillarity. Local indices of capillary supply have the potential to identify the onset of fine-scale tissue pathologies and dysregulation. Detailed tissue geometry, such as muscle fibre size, has been incorporated into such measures by considering the distribution of Voronoi polygons (VP) generated from planar capillary locations as a representation of capillary supply regions. Previously, detailed simulations have predicted that this is generally accurate for muscle tissue with uniform oxygen uptake. Here we extend this modelling framework to heterogeneous muscle for the assessment of capillary supply capacity under maximal sustainable oxygen consumption. We demonstrate for muscle with heterogeneous fibre properties that VP theoretically provide a computationally simple but often accurate representation of trapping regions (TR), which are predicted from biophysical transport models to represent the areas of tissue supplied by individual capillaries. However, this use of VP may become less accurate around large fibres, and at the interface of fibres of largely different oxidative capacities. In such cases, TR may provide a more robust representation of capillary supply regions. Additionally, given VP can only approximate oxygen delivery by capillaries, we show that their generally close relationship to TR suggests that (1) fibre type distribution may be tightly regulated to avoid large fibres with high oxidative capacities, (2) the anatomical fibre distribution is also tightly regulated to prevent large surface area of interaction between metabolically dissimilar fibres, and (3) in chronically hypoxic tissues capillary distribution is more important in determining oxygen supply than the spatial heterogeneity of fibre demand.

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Section: Discussionsupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Modelling capillary oxygen supply capacity in mixed muscles: Capillary domains revisited

Alshammari

Gaffney

Egginton

2014

Journal of Theoretical Biology

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“…the gastrocnemius [Chernukh and Alekseeva, 1975;Tyml et al, 1999] and soleus muscles [Čebašek et al, 2006;Degens et al, 2008], show regression of capillaries already in the early denervation period. Tyml et al [1999] speculated that such a specific postponed decrease in EDL capillaries to early denervation could be a consequence of the specific high susceptibility of EDL muscles to sympathectomy, because they have observed an increased blood flow after tetrodotoxin denervation (that could induce angiogenesis or prevent rarefaction of capillaries) only in the EDL but not in gastrocnemius muscles.…”

Section: Muscle Fibre Morphometry and Capillary Characteristicsmentioning

confidence: 99%

Changes in the Capillarity of the Rat Extensor Digitorum Longus Muscle 4 Weeks after Nerve Injury Studied by 2D Measurement Methods

Čebašek¹,

Ribarič

2016

Cells Tissues Organs

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We have previously shown by 3D study that 2 weeks after nerve injury there was no change in the length of capillaries per muscle fibre length in rat extensor digitorum longus muscle (EDL). The primary goal of the present 2D study was to determine the capillarity of rat EDL 4 weeks after various modes of nerve injury. Additionally, we wished to calculate the same capillary/fibre parameters that were used in our 3D stereological study. EDL muscles derived from denervated (4 weeks after nerve injury), re-innervated (4 weeks after two successive nerve crushes) and age-matched controls from the beginning (CON-1) and the end (CON-2) of the experiment were analysed in two ways. Global indices of capillarity, such as capillary density (CD) and capillary/fibre (C/F) ratio, were determined by automatic analysis, local indices as the number (CAF) and the length of capillaries around individual muscle fibres (Lcap) in relation to muscle fibre size were estimated manually by tracing the muscle fibre outlines and the transversally and longitudinally cut segments of capillaries seen in 5-µm-thin muscle cross sections. Four weeks after both types of nerve injury, CD increased in comparison to the CON-2 group (p < 0.001) due to atrophied muscle fibres in denervated muscles and probably proliferation of capillaries in re-innervated ones. Higher C/F, CAF (both p < 0.001) and Lcap (p < 0.01) in re-innervated than denervated EDL confirmed this assumption. Calculated capillary/fibre parameters were comparable to our previous 3D study, which strengthens the practical value to the adapted 2D method used in this study.

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“…Yet, we did not observe a more homogeneous distribution of capillaries after exposure to hypoxia, not even in the glycolytic region that became more oxidative. Also, during hypertrophy (16) and atrophy (15), the heterogeneity of capillary spacing remains unaltered, and it has been suggested that the absence of changes might be related to physical constraints, determined by the morphology of the muscle fibers, of placing new capillaries (16).…”

Section: Overall Adaptations To Chronic Hypoxiamentioning

confidence: 99%

Region-specific adaptations in determinants of rat skeletal muscle oxygenation to chronic hypoxia

Wüst

Jaspers²,

Heijst³

et al. 2009

American Journal of Physiology-Heart and Circulatory Physiology

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Chronic exposure to hypoxia is associated with muscle atrophy (i.e., a reduction in muscle fiber cross-sectional area), reduced oxidative capacity, and capillary growth. It is controversial whether these changes are muscle and fiber type specific. We hypothesized that different regions of the same muscle would also respond differently to chronic hypoxia. To investigate this, we compared the deep (oxidative) and superficial (glycolytic) region of the plantaris muscle of eight male rats exposed to 4 wk of hypobaric hypoxia (410 mmHg, Po(2): 11.5 kPa) with those of nine normoxic rats. Hematocrit was higher in chronic hypoxic than control rats (59% vs. 50%, P < 0.001). Using histochemistry, we observed 10% fiber atrophy (P < 0.05) in both regions of the muscle but no shift in the fiber type composition and myoglobin concentration of the fibers. In hypoxic rats, succinate dehydrogenase (SDH) activity was elevated in fibers of each type in the superficial region (25%, P < 0.05) but not in the deep region, whereas in the deep region but not the superficial region the number of capillaries supplying a fiber was elevated (14%, P < 0.05). Model calculations showed that the region-specific alterations in fiber size, SDH activity, and capillary supply to a fiber prevented the occurrence of anoxic areas in the deep region but not in the superficial region. Inclusion of reported acclimatization-induced increases in mean capillary oxygen pressure attenuated the development of anoxic tissue areas in the superficial region of the muscle. We conclude that the determinants of tissue oxygenation show region-specific adaptations, resulting in a marked differential effect on tissue Po(2).

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The time course of denervation-induced changes is similar in soleus muscles of adult and old rats

Cited by 25 publications

References 33 publications

Modelling capillary oxygen supply capacity in mixed muscles: Capillary domains revisited

Modelling capillary oxygen supply capacity in mixed muscles: Capillary domains revisited

Changes in the Capillarity of the Rat Extensor Digitorum Longus Muscle 4 Weeks after Nerve Injury Studied by 2D Measurement Methods

Region-specific adaptations in determinants of rat skeletal muscle oxygenation to chronic hypoxia

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