| Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1990: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1989: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
The purpose of this study was to examine the glycogen depletion patterns in specific fiber types in the respiratory muscles during prolonged exercise. In addition, it was to examine whether the metabolism of glycogen in the respiratory muscle is improved by endurance training.
Five-week-old and 15-week-old female Wistar rats were used in this study. Five-week-old rats were trained to run 30 min/day, 3 times/week, for 10 weeks on a treadmill. The training speed was equal to 70 % of their Vo_2max.
Following the training program, 5-week-old rats and then 15-week-old rats were forced to test run on a treadmill for 20, 40 or 60 minutes at a speed equivalent to 70% of their Vo_2max. Immediately after the run, all the rats were anaesthetized with ether and then the diaphragm, the intercostal muscles and the rectus femoris were removed and frozen. Samples for histochemistry were cut in a cryostat and stained for myosin ATPase and PAS. Other samples were examined for glycogen content. Staining intensity of the PAS stain were classified into 16 stage by a video image analyzer.
The glycogen content of the respiratory muscle of 15-week-old rats decreased by half after 20 minutes of exercise. With further exercise no further reduction in glycogen was observed in any of the muscles. A glycogen decrease in specific fiber types showed the same pattern.
Therefore, it is obvious that the all fiber types of the respiratory muscle were mobilized during the severe prolonged exercise. Glycogen storage was increased by endurance training ; and the glycogen content in every respiratory muscle and in every fiber type during exercise was maintained at higher levels following training. Therefore, this suggests that the metabolism of glycogen in respiratory muscles is improved by endurance training.
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