Katz A, Raz I
Division of Clinical Physiology, Karolinska Hospital, Stockholm, Sweden.
Pflugers Arch. 1995 Dec;431(2):259-65. doi: 10.1007/BF00410199.
The effects of isometric contraction (66% of maximal force) and recovery on glycogen synthase fractional activity (GSF) in human skeletal muscle have been studied. Biopsies were taken from the quadriceps femoris muscle at rest, at fatigue and 5 min postexercise on two occasions: after one of the contractions, the circulation to the thigh was occluded during the 5 min recovery (OCC), and after the other contraction, the circulation was intact (control, CON). During CON, GSF decreased from (mean +/- SE) 0.34 +/- 0.05 at rest to 0.24 +/- 0.02 at fatigue and then increased to 0.74 +/- 0.04 at 5 min postexercise; corresponding values for OCC were 0.37 +/- 0.04, 0.25 +/- 0.04 and 0.48 +/- 0.05 (P < 0.001 vs. CON for 5 min postexercise only). Compared with the value at fatigue, protein phosphatase activity (PP) increased by 79 +/- 16% during CON recovery (P < 0.01), whereas no change was observed during OCC recovery. Uridine diphosphate glucose increased by approximately 2.5-fold at fatigue, remained elevated during OCC recovery, but reverted to the preexercise level during CON recovery (P < 0.001 vs. OCC recovery). Glucose 6-P increased approximately 5-fold at fatigue and was higher at 5 min postexercise in OCC vs. CON recovery (8.6 +/- 1.5 vs. 4.1 +/- 0.9 mmol/kg dry wt; P < 0.01). It is concluded that the rapid increase in GSF after intense exercise with an intact circulation may be at least partly attributed to an increase in the specific activity of PP. The increase in GSF during recovery in OCC may be at least partly attributed to the high glucose 6-P content in vivo, which enhances the substrate suitability of GS for PP. Thus, separate mechanisms exist for the activation of PP and GS during recovery from intense short term exercise.
研究了等长收缩（最大力量的66%）及恢复过程对人体骨骼肌糖原合酶分数活性（GSF）的影响。在两种情况下，于静息状态、疲劳状态以及运动后5分钟从股四头肌取活检样本：一次收缩后，在5分钟恢复期间阻断大腿血液循环（OCC）；另一次收缩后，血液循环保持完整（对照组，CON）。在CON组中，GSF从静息时的（均值±标准误）0.34±0.05降至疲劳时的0.24±0.02，然后在运动后5分钟升至0.74±0.04；OCC组的相应值分别为0.37±0.04、0.25±0.04和0.48±0.05（仅运动后5分钟时，与CON组相比P<0.001）。与疲劳时的值相比，CON组恢复期间蛋白磷酸酶活性（PP）增加了79±16%（P<0.01），而OCC组恢复期间未观察到变化。尿苷二磷酸葡萄糖在疲劳时增加约2.5倍，在OCC组恢复期间保持升高，但在CON组恢复期间恢复至运动前水平（与OCC组恢复相比P<0.001）。葡萄糖6 - 磷酸在疲劳时增加约5倍，运动后5分钟时OCC组高于CON组恢复（8.6±1.5对4.1±0.9 mmol/kg干重；P<0.01）。得出结论，在血液循环完整的剧烈运动后GSF的快速增加可能至少部分归因于PP比活性的增加。OCC组恢复期间GSF的增加可能至少部分归因于体内高葡萄糖6 - 磷酸含量，其增强了GS对PP的底物适应性。因此，在短期剧烈运动恢复过程中，PP和GS的激活存在不同机制。
