Juel C, Grunnet L, Holse M, Kenworthy S, Sommer V, Wulff T
Copenhagen Muscle Research Centre, August Krogh Institute, University of Copenhagen, Universitetsparken 13, 2100, Denmark.
Pflugers Arch. 2001 Nov;443(2):212-7. doi: 10.1007/s004240100674.
Exercise-induced translocation of Na+-K+ pump subunits to the sarcolemmal membrane was studied using sarcolemmal giant vesicles as a membrane purification procedure. The subunit content was quantified by Western blotting or by ouabain labeling. Low-intensity treadmill running increased (P<0.01) the alpha1, alpha2, beta1, and beta2 subunit contents by 19-32% in membranes from oxidative muscle fibers and the alpha1, alpha2, and beta2 contents increased by 13-25% in membranes from glycolytic muscle fibers. Ouabain labeling of membranes from mixed fibers was increased by 29% after exercise. A similar increase in subunit content could be induced by 5 min of fatiguing, high-intensity electrical stimulation of isolated soleus muscles. An increased subunit content was just detectable in vesicles produced 30 min after exercise, and the content was completely back to control levels 3 h after exercise. It is concluded that both low-intensity long-lasting running and short-lasting high-intensity contractions are able to induce a translocation of pump subunits to the sarcolemmal membrane. The post-exercise disappearance of the extra subunits (half-time approximately 20 min) from the membrane demonstrates the reversible nature of the translocation process.
采用肌膜巨型囊泡作为膜纯化方法，研究了运动诱导的Na⁺-K⁺泵亚基向肌膜的转位。通过蛋白质免疫印迹法或哇巴因标记对亚基含量进行定量。低强度跑步机跑步使氧化型肌纤维膜中的α1、α2、β1和β2亚基含量增加（P<0.01）19% - 32%，糖酵解型肌纤维膜中的α1、α2和β2含量增加13% - 25%。运动后，混合纤维膜的哇巴因标记增加了29%。对分离的比目鱼肌进行5分钟疲劳性高强度电刺激，可诱导亚基含量出现类似增加。运动后30分钟产生的囊泡中，亚基含量仅可检测到增加，运动3小时后含量完全恢复至对照水平。得出的结论是，低强度持久跑步和短时间高强度收缩均能够诱导泵亚基向肌膜转位。运动后膜中额外亚基的消失（半衰期约20分钟）证明了转位过程的可逆性。
