Dupont-Versteegden E E, McCarter R J
Department of Physiology, UT Health Science Center San Antonio 78284.
Muscle Nerve. 1992 Oct;15(10):1105-10. doi: 10.1002/mus.880151008.
Contractile properties of diaphragm (DIA) from mdx and control mice were compared with those of hindlimb muscles [soleus (SOL) and extensor digitorum longus (EDL)] in vitro. Mice ranged in age from 2 weeks to 1.5 years. Muscles were directly stimulated and properties measured were: contraction time, half-relaxation time, active tension per unit area, fatigue index, and maximal velocity of shortening (Vmax). Active tension decreased significantly with age in mdx DIA but not in control DIA. SOL and EDL active tensions were less in mdx than control over the whole age range and did not decrease with age. Vmax was decreased in mdx DIA, but not in mdx SOL or EDL. These results demonstrate that DIA is more affected by muscular dystrophy than hindlimb muscles. Since many Duchenne patients exhibit respiratory distress, this differential expression of dystrophy in diaphragm, as compared to limb muscles, may have important clinical implications.
在体外比较了mdx小鼠和对照小鼠膈肌（DIA）与后肢肌肉[比目鱼肌（SOL）和趾长伸肌（EDL）]的收缩特性。小鼠年龄范围从2周龄至1.5岁。直接刺激肌肉并测量的特性包括：收缩时间、半松弛时间、单位面积的主动张力、疲劳指数和最大缩短速度（Vmax）。mdx DIA的主动张力随年龄显著降低，而对照DIA则不然。在整个年龄范围内，mdx小鼠的SOL和EDL主动张力低于对照小鼠，且不随年龄降低。mdx DIA的Vmax降低，但mdx SOL或EDL的Vmax未降低。这些结果表明，与后肢肌肉相比，DIA受肌肉营养不良的影响更大。由于许多杜兴氏患者表现出呼吸窘迫，与肢体肌肉相比，膈肌中营养不良的这种差异表达可能具有重要的临床意义。
