Abstract
The effects of 5 weeks of physical exercise and/or 10 minutes long electrical stimulation on the intensities of PAS-reaction were studied in various types of muscle fibers. The recordings were made according to the intensity of Sudan black B (SBB) stain, using the anterior tibialis muscles of rats. As for the nonstimulated muscles, an inverse relationship was generally observed between the intensity of SBB-stain and PAS-reaction in both trained and untrained rats. A few strongly-SBB-positive fibers, however, showed also strongly-PAS-positive. The frequency of fibers showing strongly positive reaction in both stainings was slightly higher in the trained rats than in the untrained. After the electrical stimulation was given, the PAS-reaction was observed to decrease in the SBB-negative fibers and to increase in the strongly-SBB-positive fibers. The response of the strongly-SBB-positive fibers to the stimulation, however, was more prominent in the trained than in the untrained. PAS-reaction in the fibers rated as moderate in the SBB-stain slightly decreased after the stimulation in the trained rats, whereas that in the untrained slightly increased.
