Gordon T, Stein R B
Exp Neurol. 1985 Aug;89(2):348-60. doi: 10.1016/0014-4886(85)90095-0.
The kinetics of isolated extensor digitorum longus and soleus muscles from normal and genetically dystrophic (129/ReJ dy/dy) mice were studied at temperatures from 8 to 38 degrees C. The rate constants for the exponential rise of tetanic force and for the exponential decay of force during an isometric twitch or short tetanus were similar in normal and dystrophic soleus muscles, but the decay rates were significantly reduced in dystrophic extensor digitorum longus muscles. The temperature dependence for several rate constants for isometric twitches and tetani was similar in all muscles studied, suggesting that the same rate limiting processes apply to fast and slow, normal and dystrophic muscles. Thus, the contractile proteins and those in the sarcoplasmic reticulum of dystrophic muscle are probably normal. The slower relaxation phase in dystrophic extensor digitorum longus muscles is compatible with a reduction in Ca2+-pumping sites in the sarcoplasmic reticulum, perhaps secondary to a change in motor unit composition. Some changes in the temperature dependence for measured times, toward those of soleus muscles, is consistent with the increased proportion of slow twitch motor units in dystrophic extensor digitorum longus muscles.
研究了正常小鼠和遗传性营养不良（129/ReJ dy/dy）小鼠的离体趾长伸肌和比目鱼肌在8至38摄氏度温度下的动力学。在正常和营养不良的比目鱼肌中，强直收缩力指数上升的速率常数以及等长单收缩或短强直收缩期间力的指数衰减速率常数相似，但在营养不良的趾长伸肌中，衰减速率显著降低。在所有研究的肌肉中，等长单收缩和强直收缩的几个速率常数的温度依赖性相似，这表明相同的速率限制过程适用于快肌和慢肌、正常肌和营养不良肌。因此，营养不良肌肉的收缩蛋白和肌浆网中的蛋白可能是正常的。营养不良的趾长伸肌中较慢的舒张期与肌浆网中Ca2+泵位点的减少相一致，这可能继发于运动单位组成的变化。测量时间的温度依赖性向比目鱼肌的温度依赖性的一些变化，与营养不良的趾长伸肌中慢收缩运动单位比例的增加是一致
