Abstract
The purpose of this study was to investigate the glycogen restoration and AMPK protein expression in post-exercised rats under recovery with different oxygen concentrations. Forty-eight Sprague Dawley rats (weighing 250 grams) were divided into exercise and non-exercise groups (control) and recovered under normobaric, normobaric-hypoxia (FIO2 = 14%) and normobaric-hyperoxia (FIO2 = 83%) conditions. In exercise groups rats were allowed to swim for 3-h continuously, and then recovered for 1-h under three different oxygen concentrations. After recovery the blood glucose levels were not significantly altered between exercise and non-exercise groups. Insulin levels were similar with blood glucose levels during recovery. The glycogen content in cardiac muscle was significantly increased in exercise groups compared to non-exercise groups after recovery, but no difference in liver glycogen between exercise and non-exercise groups. On the other hand, white quadriceps glycogen content was significantly decreased in exercise group, but restoration of glycogen under hypoxia recovery was higher than hyperoxia recovery in exercise group. Interestingly, the glycogen restoration in red quadriceps was similar with white quadriceps. The total AMPK protein expression was no difference between exercise and non-exercise groups; however, the phosphorylated AMPK protein was higher in hyperoxia than hypoxia in white quadriceps. Our findings conclude that the restoration of glycogen in cardiac muscle was taken into first priority than the other tissues. Furthermore, normobaric hypoxia condition would be helpful for the glycogen restoration in muscle after exercise, and AMPK signal pathway may not be the key factor for glycogen restoration in rats.