[Morphological changes of muscle and capillary endothelial cells after aerobic exercise training under different...

The morphological changes of muscle cells and capillary endothelial cells of skeletal muscles were in wshigutet after long-term exercise training at various temperatures. One-hundred and forty rats were divided into seven groups and received a one-month exercise training at conditions of low (0 degree C), normal (26 degrees C) or high (42 degrees C) temperatures respectively. Muscle samples were obtained from extensor digitorum longus muscle (EDL) and soleus muscle (SOL) of each animal. These samples were used to observe the hitological differences by light microscope, and to observe the changes in the number of muscular mitochondria and capillary endothelial pinocytotic vesicles by electron microscope. We found that both low and high temperature groups had higher frequency of atrophy and necrosis in muscle fibers than the normal temperature group. Moreover, EDL muscle had significantly more mitochondria and pinocytotic vesicle than SOL muscle in the high and normal temperature groups. From these results, we suggested that changes of the environmental temperature cause histological malformations of muscle fibersabtw; in addition, these effects were more prominent in fast twitch muscles.