ラット下肢筋の筋線維伝導速度と筋線維組成

概要

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To investigate whether muscle fiber conduction velocity reflects muscle fiber type, we studied the extensor digitorum longus (EDL) and soleus (SOL) muscle in 7 male rats aged 12 weeks. Muscle fiber conduction velocity was measured with a surface electrode array during stimulated contraction and calculated from the delay between two action potentials along muscle fibers for a given inter-electrode distance. Conduction velocity in the EDL (2.71±0.50 m/s) was significantly higher (P<0.05) than that in the SOL (2.14±0.34 m/s). Fiber type, fiber area and fiber diameter were determinated by myosin ATPase staining and NADH-tetrazolium reductase staining. Muscle fiber composition of the EDL and SOL was 94.6±1.8% and 14.8±4.3% FT fibers, respectively, and mean muscle fiber diameter was 62.7±6.2 μm and 79.2±7.8 μm, respectively, that of the EDL being significantly smaller (P<0.01) than that of the SOL. It was suggested that individual differences in conduction velocity were caused by differences in muscle fiber composition rather than differences in muscle diameter.
1992-02-01