Wieneke S, Stehle R, Li Z, Jockusch H
Developmental Biology Unit, University of Bielefeld, Bielefeld, D-33501, Germany.
Biochem Biophys Res Commun. 2000 Nov 19;278(2):419-25. doi: 10.1006/bbrc.2000.3810.
We have investigated the physiological role of desmin in skeletal muscle by measuring isometric tension generated in skinned fibres and intact skeletal muscles from desmin knock-out (DES-KO) mice. About 80% of skinned single extensor digitorum longus (EDL) fibres from adult DES-KO mice generated tensions close to that of wild-type (WT) controls. Weights and maximum tensions of intact EDL but not of soleus (SOL) muscles were lowered in DES-KO mice. Repeated contractions with stretch did not affect subsequent isometric tension in EDL muscles of DES-KO mice. Tension during high frequency fatigue (HFF) declined faster and this deficiency was compensated in DES-KO EDL muscles by 5 mM caffeine which had no influence on HFF in WT EDL. Furthermore, caffeine evoked twitch potentiation was higher in DES-KO than in WT muscles. We conclude that desmin is not essential for acute tensile strength but rather for optimal activation of intact myofibres during E-C coupling.
我们通过测量来自结蛋白基因敲除（DES-KO）小鼠的去表皮肌纤维和完整骨骼肌产生的等长张力，研究了结蛋白在骨骼肌中的生理作用。成年DES-KO小鼠约80%的去表皮单根趾长伸肌（EDL）纤维产生的张力接近野生型（WT）对照。DES-KO小鼠中，完整EDL肌肉的重量和最大张力降低，但比目鱼肌（SOL）肌肉未受影响。DES-KO小鼠的EDL肌肉在重复拉伸收缩后，后续等长张力不受影响。DES-KO小鼠EDL肌肉在高频疲劳（HFF）期间张力下降更快，5 mM咖啡因可弥补DES-KO EDL肌肉的这一缺陷，而该浓度咖啡因对WT EDL肌肉的HFF无影响。此外，DES-KO小鼠中咖啡因诱发的抽搐增强作用高于WT肌肉。我们得出结论，结蛋白对于急性抗张强度并非必不可少，而是对于兴奋-收缩偶联期间完整肌纤维的最佳激活至关重要。
