Viru M, Litvinova L, Smirnova T, Viru A
Department of Exercise Biology, Tartu University, Estonia.
J Sports Med Phys Fitness. 1994 Dec;34(4):377-82.
In order to evaluate the participation of glucocorticoids in the control of glycogen metabolism during exercise, experiments were performed on male adrenalectomized and normal rats. In adrenalectomized rats swimming for 4 hours induced less pronounced increases in lactate concentrations in skeletal muscles than in normal rats (in FG fibers up to 10.7 +/- 1.0 vs 14.8 +/- 1.2 and in SO fibers up to 9.1 +/- 0.7 vs 12.5 +/- 0.7 mg x g-1 wet tissue). The glycogen drop in liver and oxidative muscles was also less pronounced (in liver by 14% vs 52%, in SO fibers by 33% vs 54% in normal rats). Swimming until exhaustion led to an extremely low glucose level in blood (1.89 +/- 0.12 mMol x L-1) in adrenalectomized rats. When they were treated with dexamethasone, the swimming duration was longer (12 +/- 1 hours vs 9 +/- 0.8 hours in saline treated), blood glucose level at exhaustion was higher (3.07 +/- 0.23 mMol x L-1) and the drop of hepatic and muscle glycogen was more pronounced. In normal rats hepatic glycogen content dropped by 68% after swimming for 4 hours. After swimming for 8 or 12 hours further decreases in hepatic glycogen content were insignificant. High levels of corticosterone in blood was found after swimming for 4 and 8 hours. After swimming for 16 hours corticosterone concentration was below normal and a new drop in liver glycogen (until a level constituting only 11% initial) was recorded. The results support the suggestion that glucocorticoids, regulate hepatic glycogen and peripheral glucose utilization during exercise, and also participate in the control of glycogenolysis in muscles.
为了评估糖皮质激素在运动过程中对糖原代谢控制的参与情况，对雄性肾上腺切除大鼠和正常大鼠进行了实验。在肾上腺切除大鼠中，游泳4小时导致骨骼肌中乳酸浓度的升高不如正常大鼠明显（在快肌纤维中高达10.7±1.0 vs 14.8±1.2，在慢肌纤维中高达9.1±0.7 vs 12.5±0.7毫克×克-1湿组织）。肝脏和氧化型肌肉中的糖原下降也不那么明显（肝脏中分别为14% vs 52%，慢肌纤维中为33% vs 54%，正常大鼠中为54%）。游泳至疲惫导致肾上腺切除大鼠血液中的葡萄糖水平极低（1.89±0.12毫摩尔×升-1）。当用 dexamethasone 治疗时，游泳持续时间更长（12±1小时 vs 生理盐水治疗组的9±0.8小时），疲惫时的血糖水平更高（3.07±0.23毫摩尔×升-1），肝脏和肌肉糖原的下降更明显。在正常大鼠中，游泳4小时后肝脏糖原含量下降了68%。游泳8或12小时后，肝脏糖原含量的进一步下降不明显。游泳4小时和8小时后，血液中发现高水平的皮质酮。游泳16小时后，皮质酮浓度低于正常水平，并且记录到肝脏糖原的新下降（直至仅为初始水平的11%）。这些结果支持了以下观点：糖皮质激素在运动过程中调节肝脏糖原和外周葡萄糖利用，并且还参与肌肉糖原分解的控制。
