Abstract
It is generally accepted that the physical capacity accompanied with aging decreases. In order to investigate a reason of reduction of the physical capacity, changes of skeletal muscle glycogen in the aged rats were mainly investigated.
Body weight and skeletal muscle, ventricular muscle and liver weights with aging in rats were examined, and their physical capacity was tested by treadmill running. At the same time, changes of blood glucose, lactate and plasma FFA, plasma triglyceride and muscle glycogen (tibialis anterior, extensor digitorum longus (EDL), soleus, plantaris, gastrocnemius) in these animals were determined under the post-absorptive state at 30, 105, 350 and 540 days, respectively. Body weight of rats were maximum at 360 days, thereafter slightly decreased. The rate of muscle weight to the body weight reduced slightly with aging, but no significance was statistically observed. Furthermore, no change of ventricular muscle and liver weights to the body weight were observed with aging, except the 30 days rat. Glycogen contents of EDL, plantaris and white region of gastrocnemius in 540 days rats significantly decreased comparing 105 days rats, but there were no changes on glycogen contents in soleus and red region of gastrocnemius. In post-absorptive state, muscle glycogen in 30 days rats decreased more 2 fold than that in young adult rats. On the other hand, ventricular glycogen increased at fasting. Blood glucose and plasma FFA were not influenced by aging, while plasma triglyceride rose 2.5 fold.
