Effect of chronic hypoxia on skeletal muscle fiber type in adult male rats.

Abstract

The effects of chronic hypoxia on muscle fiber distribution were investigated in 10-week-old male Wistar rats. Samples of the soleus and the plantaris muscles were extracted after the animals were exposed to normobaric hypoxia (10% O2) for 4 weeks. Histochemical myosin-based classification of skeletal muscle fibers was used. There was no evidence of transformation between different fiber types in either muscles. These results differ from those of previous studies. The rats used in those studies were younger, and it is difficult to distinguish the conversion of fiber types that occurs during normal development from other factors. These data suggest that chronic hypoxia does not affect muscle fiber type in adult rats.