| The animal studies have demonstrated that ginsenoside Rgl (GS Rgl ) has the actions of enhancing physical endurance and delaying the development of exercise-induced fatigue. However, little has been known about the mechanism of its actions. This study investigated the effects of GS Rgl on the carbohydrate metabolism and the serum levels of related hormones in swimming rats to provide experimental evidences to the understanding of the mechanisms underlying its enhancing-endurance actions.42 rats were randomly divided into 6 groups of 7 rats each. Rats of 5 groups were injected intrapearitoneally (i. p.) with GS Rgl of 10, 15, 20, 25 or 30 mg per kilogram of body mass and per day (mg kg-1 d-1 ) for two days and the rats of another group were injected i.p. with the same volume of saline at equivalent times. The exhaustive swimming times (ESTs ) of these rats were measured starting with 1h after the second i. p. Afterwards, 84 rats were randomly divided into 12 groups, containing 7 rats per group. 6 groups of the rats were given two i.p. injections of 20 mg GS Rgl kg-1 d-1. The remaining animals received the i. p. injections of saline vehicle and served as controls. The glycogen contents of liver and muscle tissues and the serum levels of glucose, lactate, insulin and glucagon were examined at rest and during swimming. The following results were obtained.1. The ESTs of all GS Rgl -treated groups were longer than those of the saline-treated control groups. Furthermore, there were significant differences between the groups given GS Rgl of 10~30 mg kg-1 d-1 and the control groups (p < 0.05 or p < 0.01). The ESTs of the GS Rgl -treated groups increased rapidly with the increase of the GS Rgl doses in the range of 5~15 mg kg-1 d-1, and then did slowly above 15mg-kg-1 . d-1.2. At rest, there were not any significant differences (p > 0.05) between the GS Rgl- and the saline-treated control groups in the contents of muscle and liver glycogen and the serum concentrations of glucose, lactate, insulin and glucogan.3. While the muscle glycogen contents of both GS Rgl- and saline-treated groups decreased gradually during swimming, the values of the formers decreased more slowly than the lalters. Compared to the rest control groups, significant declines of the muscle glycogen content were obtained in saline-treated groups after 0.5h swimming, whereas in GS Rgl-treated groups after 1h swimming. The muscle glycogen contents of the GS Rgl groups were significantly higher than those of saline groups at 1h, 1.5h, 2h and 3h after the beginning of swimming.4. The liver glycogen contents of GS Rgl- and saline-treated groups decreased with prolonging of swimming duration, and were markedly lower than the rest control groups after 1 h swimming. After this, the declines of liver glycogen contents slowed in the GS Rgl-treated groups, but did not in the saline-treated groups. The liver glycogen contents of GS Rgl groups were significantly higher than those of the saline groups after 2h and 3h swimming.5. The serum glucose of GS Rgl-treated groups had a little decline during swimming, while that of the saline-treated groups declined quickly and the values of decline reached about 24%, 30%, 35% of the serum glucose of rest-control groups at 1.5h, 2h and 3h after the beginning of swimming respectively. At these 3 time-points, the glucose levels of GS Rgl-treated groups were significantly higher than the saline-treated ones.6. During swimming, the serum lactate concentrations of the GS Rgl-treated groups did not increase significantly (p>0.05). However, the lactate concentrations of the saline-treated groups increased quickly and reached four-times as high as the rest groups after 1h swimming, and then declined but still were higher than the rest and the GS Rgl-treated groups. There were significant difference between the lactateconcentrations of the GS RgI- and the saline-treated groups at 0.5, 1h and 1.5h after the beginning of swimming.7. The serum insulin levels of (he G... |
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