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  • 1
    Electronic Resource
    Electronic Resource
    Effects of age and life-time physical training on fibre composition of slow and fast skeletal muscle in rats (1987)
    Springer
    Pflügers Archiv 408 (1987), S. 543-551 
    Details
    ISSN: 1432-2013
    Keywords: Fibre types ; Fibre transformation ; Enzymes of energy metabolism ; Slow and fast skeletal muscle ; Rat ; Age ; Endurance training
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of age and endurance training on muscle fibre characteristics were studied in a slow (m. soleus, MS) and in a fast (m. rectus femoris, MRF) skeletal muscle. Wistar rats at ages of 1, 2, 4, 10, and 24 months were used as experimental animals. The trained rats were put to run on a motor-driven treadmill 5 d/wk beginning from the age of 1 month. The body weights of the animals increased continuously throughout their lives. The muscle weights increased up to the age of 10 months, after which they tended to decrease. The trained adult rats had lower body weights as well as lower muscle weights than the untrained adult rats. The amount of the intramuscular lipid decreased with age, especially during the first months of life. The activity of isocitrate dehydrogenase (ICDH) decreased during the growth period in both muscles and remained more or less constant thereafter, whereas the activity of phosphofructokinase decreased with age only in MS. In MS, the trained animals tended to have higher ICDH activities than the untrained animals. The cross-sectional area of the different fibre types in both muscles increased up to the age of 10 months. The major fibre types, type I in MS and type IIB in MRF, were smaller for trained than untrained rats. The percentage number of the slower fibre types of both muscles — type I in MS and types I and IIA in MRF —increased with advancing age. The muscles of the trained animals contained higher percentages of the slower fibre types than those of the untrained rats. The present paper indirectly supports the opinion that not only the metabolic but also the contractile properties of different muscle cell types can be changed by age and long-term endurance-type physical training.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581154
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  • 2
    Electronic Resource
    Electronic Resource
    Increased mRNAs for procollagens and key regulating enzymes in rat skeletal muscle following downhill running (1999)
    Springer
    Pflügers Archiv 437 (1999), S. 857-864 
    Details
    ISSN: 1432-2013
    Keywords: Key words Collagen ; Skeletal muscle ; Prolyl 4-hydroxylase ; Lysyl oxidase ; Hydroxyproline ; Damage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The purpose of the study was to investigate pre-translational regulation of collagen expression after a single bout of exercise. We analysed steady-state messenger ribonucleic acid (mRNA) levels for collagen types I, III and IV, α- and β-subunits of prolyl 4-hydroxylase and lysyl oxidase (enzymes modifying procollagen chains), and enzyme activity of prolyl 4-hydroxylase from rat soleus muscle (MS) and the red parts of quadriceps femoris muscle (MQF) after 12 h and after 1, 2, 4, 7 and 14 days of downhill (–13.5°) treadmill running at a speed of 17 m·min–1 for 130 min. Histological and biochemical assays revealed exercise-induced muscle damage in MQF but not MS. Steady-state mRNA levels for the α- and β-subunits of prolyl 4-hydroxylase in MQF, lysyl oxidase in MS and MQF were increased 12 h after running, whereas prolyl 4-hydroxylase activity did not increase until 2 days after exercise. The mRNA levels for the fibrillar collagens (I and III) and basement membrane type IV collagen significantly increased 1 day and 12 h after exertion, respectively. Peak mRNA levels were observed 2–4 days after running, the increases being more pronounced in MQF than in MS. No significant changes were observed in types I or III collagen at the protein level. Strenuous downhill running thus causes an increase in gene expression for collagen types I and III and their post-translational modifying enzymes in skeletal muscle in a co-ordinated manner. These changes, together with the increased gene expression of type IV collagen, may represent the regenerative response of muscle extracellular matrix to exercise-induced injury and an adaptive response to running exertion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050855
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of prolonged exposure to and physical training in hypobaric conditions on skeletal muscle morphology and metabolic enzymes in rats (1996)
    Springer
    Pflügers Archiv 432 (1996), S. 50-58 
    Details
    ISSN: 1432-2013
    Keywords: Key words Hypobaric hypoxia ; Physical training ; Skeletal muscle ; Muscle fibre type ; Fibre cross-sectional area ; Enzymes of energy metabolism ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Adaptations of skeletal muscle morphology and metabolic enzymes were studied after prolonged training in and exposure to hypobaric (740 –770 mbar) as well as normobaric conditions in rats performing treadmill running training for 10, 21 and 56 days. Animals sacrificed after 91 days served as recovery groups from training and hypobaric exposure for 56 days. The rats were divided into normobaric sedentary (NS) and training (NT) groups and hypobaric sedentary (HS) and training (HT) groups. The weights of extensor digitorum longus (EDL) and soleus (SOL) muscles increased significantly in the 56HS and the 56HT groups compared with the 56NS group, the increase being greatest in the 56HS group. No differences in the mean fibre areas (MFA) of these muscles could be seen, whereas clearly reduced MFAs of type IIA and IIB were observed in the tibialis anterior (TA) muscle. However, fibre area distribution analyses in the EDL and TA muscles showed a higher proportion of larger fibers in the 56HS and 56HT groups than in the respective normobaric groups. On the contrary, in SOL muscles the proportion of smaller fibers was higher in the hypobaric than in normobaric groups at 56 days. Increased activities of citrate synthase and β-hydroxyacyl-CoA-dehydrogenase in SOL and TA muscles in the 56HT group indicate an increase in oxidative capacity. It is concluded that exposure to, and training in moderate hypobaric conditions leads to a positive muscle protein balance which is reflected in increased muscle weights. However, the sites of increased protein synthesis and the possible hyperplasia remain to be studied further.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050104
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  • 4
    Electronic Resource
    Electronic Resource
    Age- and training-related changes in the collagen metabolism of rat skeletal muscle (1989)
    Springer
    European journal of applied physiology 58 (1989), S. 765-771 
    Details
    ISSN: 1439-6327
    Keywords: Collagen biosynthesis ; Collagen types ; Slow and fast skeletal muscle ; Age ; Endurance training
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of ageing and life-long endurance training on the collagen metabolism of skeletal muscle were evaluated in a longitudinal study. Wistar rats performed treadmill running 5 days a week for 2 years. The activities of collagen biosynthesis enzymes, prolyl-4-hydroxylase and galactosylhydroxylysyl glucosyltransferase, were highest in the muscles of the youngest animals, decreased up to the age of 2 months and from then on remained virtually unchanged. The enzyme activity in young animals was higher in the slow collagenous soleus muscle than in the rectus femoris muscle. The enzyme activity in the soleus muscle was higher for older trained rats than older untrained rats. The relative proportion of type I collagen increased and that of type III collagen decreased with age, suggesting a more marked contribution by type I collagen to the agerelated accumulation of total muscular collagen. The results show that collagen biosynthesis decreases with maturation and that life-long endurance training maintains a higher level of biosynthesis in slow muscles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00637389
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of aging and life-long physical training on collagen in slow and fast skeletal muscle in rats (1987)
    Springer
    Cell & tissue research 248 (1987), S. 247-255 
    Details
    ISSN: 1432-0878
    Keywords: Collagen ; Slow and fast skeletal muscle ; Age ; Endurance training ; Endomysium ; Perimysium ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Intramuscular collagen in a slow (m. soleus) and a fast (m. rectus femoris) skeletal muscle was studied by biochemical, morphometric, and immunohistochemical methods. Wistar white rats of 1, 4, 10, and 24 months were used as experimental animals. Our aim was to evaluate the effects of life-long physical training (treadmill running, 5 days a week for 1, 3, 9, and 23 months depending on the age attained). The biochemical concentration of collagen was higher in m. soleus than in m. rectus femoris and it increased in youth and in old age in m. soleus. The trained rats had higher concentrations of collagen than the untrained rats at 10 and 24 months. The morphometrically measured area-fractions of both the endomysium and perimysium were higher in m. soleus than in m. rectus femoris. The age-related increase in intramuscular connective tissue was of endomysial origin. The immunohistochemical staining of type-I, -III, and -IV collagens indicated the more collagenous nature of m. soleus as compared with m. rectus femoris for all major collagen types; this was most marked for type-IV collagen of basement membrane. The results indicate that both age and endurance-type physical training further distinguish the slow and fast muscles with respect to their connective tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00218191
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