ABSTRACT The molecular signaling pathway linked to hyper-trophy of the anti-gravity/postural soleus muscle af-ter mechanical overloading has not been identified. Using Western blot and immunohistochemical analy-ses, w...ABSTRACT The molecular signaling pathway linked to hyper-trophy of the anti-gravity/postural soleus muscle af-ter mechanical overloading has not been identified. Using Western blot and immunohistochemical analy-ses, we investigated whether the amounts of NFATc3, GSK-3?, NFATc1, and neonatal MHC change in the mechanically overloaded soleus muscle after cyc-losporine A (CsA) treatment. Adult male ICR mice were subjected to a surgical ablation of the gas-trocnemius muscle and treated with either CsA (25 mg/Kg) or vehicle once daily. They were sacrificed at 2, 4, 7, 10, and 14 days post-injury. Mechanical over-loading resulted in a significant increase in the wet weight and the cross-sectional area of slow and fast fibers of the soleus muscle in placebo-treated mice but not CsA-treated mice. After 4 days of mechanical overloading, we observed a similar co-localization of neonatal MHC and NFATc3 in several myotubes of both mice. The placebo-treated mice possessed larger myotubes with neonatal MHC than CsA-treated mice. At 7 days, mechanical overloading induced marked expression of neonatal MHC in myotubes and/or myofibers. Such neonatal MHC-positive fibers emerged less often in the hypertrophied soleus mus-cle subjected to treatment with CsA. CsA treatment did not significantly change the amount of GSK-3? protein in the soleus muscle. The modulation of growth in neonatal MHC-positive myofibers by CsA treatment may inhibit the hypertrophic process in the soleus muscle after mechanical overloading.展开更多
A quantitative analysis of capillary supply to skeletal muscle is important for understanding the upper limit of the capacity for delivery of oxygen and substrates to muscle cells. It has been well documented that the...A quantitative analysis of capillary supply to skeletal muscle is important for understanding the upper limit of the capacity for delivery of oxygen and substrates to muscle cells. It has been well documented that the number of capillaries is altered by several factors including development, aging, and alteration of muscle activity level such as exercise training and inactivation. There is, however, a contradiction in animal studies for aging-related change in the number of capillaries. Human studies using biopsy technique also displayed an inconsistency on that point, in which capillary supply was not influenced or decreased with aging. This review discussed an inconsistency among studies for aging-related change in muscle capillary supply. In conclusion, the relationship between capillary supply and muscle fiber size is similar for both young and elderly population, and the morpho- logical balance between capillaries and each muscle fiber was maintained with advancing age.展开更多
文摘ABSTRACT The molecular signaling pathway linked to hyper-trophy of the anti-gravity/postural soleus muscle af-ter mechanical overloading has not been identified. Using Western blot and immunohistochemical analy-ses, we investigated whether the amounts of NFATc3, GSK-3?, NFATc1, and neonatal MHC change in the mechanically overloaded soleus muscle after cyc-losporine A (CsA) treatment. Adult male ICR mice were subjected to a surgical ablation of the gas-trocnemius muscle and treated with either CsA (25 mg/Kg) or vehicle once daily. They were sacrificed at 2, 4, 7, 10, and 14 days post-injury. Mechanical over-loading resulted in a significant increase in the wet weight and the cross-sectional area of slow and fast fibers of the soleus muscle in placebo-treated mice but not CsA-treated mice. After 4 days of mechanical overloading, we observed a similar co-localization of neonatal MHC and NFATc3 in several myotubes of both mice. The placebo-treated mice possessed larger myotubes with neonatal MHC than CsA-treated mice. At 7 days, mechanical overloading induced marked expression of neonatal MHC in myotubes and/or myofibers. Such neonatal MHC-positive fibers emerged less often in the hypertrophied soleus mus-cle subjected to treatment with CsA. CsA treatment did not significantly change the amount of GSK-3? protein in the soleus muscle. The modulation of growth in neonatal MHC-positive myofibers by CsA treatment may inhibit the hypertrophic process in the soleus muscle after mechanical overloading.
文摘A quantitative analysis of capillary supply to skeletal muscle is important for understanding the upper limit of the capacity for delivery of oxygen and substrates to muscle cells. It has been well documented that the number of capillaries is altered by several factors including development, aging, and alteration of muscle activity level such as exercise training and inactivation. There is, however, a contradiction in animal studies for aging-related change in the number of capillaries. Human studies using biopsy technique also displayed an inconsistency on that point, in which capillary supply was not influenced or decreased with aging. This review discussed an inconsistency among studies for aging-related change in muscle capillary supply. In conclusion, the relationship between capillary supply and muscle fiber size is similar for both young and elderly population, and the morpho- logical balance between capillaries and each muscle fiber was maintained with advancing age.
